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 /*

  * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "ci/bcEscapeAnalyzer.hpp"

 #include "compiler/compileLog.hpp"

 #include "libadt/vectset.hpp"

 #include "memory/allocation.hpp"

 #include "opto/c2compiler.hpp"

 #include "opto/callnode.hpp"

 #include "opto/cfgnode.hpp"

 #include "opto/compile.hpp"

 #include "opto/escape.hpp"

 #include "opto/phaseX.hpp"

 #include "opto/rootnode.hpp"

 ConnectionGraph::ConnectionGraph(Compile * C, PhaseIterGVN *igvn) :

   _nodes(C->comp_arena(), C->unique(), C->unique(), NULL),

   _in_worklist(C->comp_arena()),

   _next_pidx(0),

   _collecting(true),

   _verify(false),

   _compile(C),

   _igvn(igvn),

   _node_map(C->comp_arena()) {

   // Add unknown java object.

   add_java_object(C->top(), PointsToNode::GlobalEscape);

   phantom_obj = ptnode_adr(C->top()->_idx)->as_JavaObject();

   // Add ConP(#NULL) and ConN(#NULL) nodes.

   Node* oop_null = igvn->zerocon(T_OBJECT);

   assert(oop_null->_idx < nodes_size(), "should be created already");

   add_java_object(oop_null, PointsToNode::NoEscape);

   null_obj = ptnode_adr(oop_null->_idx)->as_JavaObject();

   if (UseCompressedOops) {

     Node* noop_null = igvn->zerocon(T_NARROWOOP);

     assert(noop_null->_idx < nodes_size(), "should be created already");

     map_ideal_node(noop_null, null_obj);

   }

   _pcmp_neq = NULL; // Should be initialized

   _pcmp_eq  = NULL;

 }

 bool ConnectionGraph::has_candidates(Compile *C) {

   // EA brings benefits only when the code has allocations and/or locks which

   // are represented by ideal Macro nodes.

   int cnt = C->macro_count();

   for (int i = 0; i < cnt; i++) {

     Node *n = C->macro_node(i);

     if (n->is_Allocate())

       return true;

     if (n->is_Lock()) {

       Node* obj = n->as_Lock()->obj_node()->uncast();

       if (!(obj->is_Parm() || obj->is_Con()))

         return true;

     }

     if (n->is_CallStaticJava() &&

         n->as_CallStaticJava()->is_boxing_method()) {

       return true;

     }

   }

   return false;

 }

 void ConnectionGraph::do_analysis(Compile *C, PhaseIterGVN *igvn) {

   Compile::TracePhase t2("escapeAnalysis", &Phase::_t_escapeAnalysis, true);

   ResourceMark rm;

   // Add ConP#NULL and ConN#NULL nodes before ConnectionGraph construction

   // to create space for them in ConnectionGraph::_nodes[].

   Node* oop_null = igvn->zerocon(T_OBJECT);

   Node* noop_null = igvn->zerocon(T_NARROWOOP);

   ConnectionGraph* congraph = new(C->comp_arena()) ConnectionGraph(C, igvn);

   // Perform escape analysis

   if (congraph->compute_escape()) {

     // There are non escaping objects.

     C->set_congraph(congraph);

   }

   // Cleanup.

   if (oop_null->outcnt() == 0)

     igvn->hash_delete(oop_null);

   if (noop_null->outcnt() == 0)

     igvn->hash_delete(noop_null);

 }

 bool ConnectionGraph::compute_escape() {

   Compile* C = _compile;

   PhaseGVN* igvn = _igvn;

   // Worklists used by EA.

   Unique_Node_List delayed_worklist;

   GrowableArray<Node*> alloc_worklist;

   GrowableArray<Node*> ptr_cmp_worklist;

   GrowableArray<Node*> storestore_worklist;

   GrowableArray<PointsToNode*>   ptnodes_worklist;

   GrowableArray<JavaObjectNode*> java_objects_worklist;

   GrowableArray<JavaObjectNode*> non_escaped_worklist;

   GrowableArray<FieldNode*>      oop_fields_worklist;

   DEBUG_ONLY( GrowableArray<Node*> addp_worklist; )

   { Compile::TracePhase t3("connectionGraph", &Phase::_t_connectionGraph, true);

   // 1. Populate Connection Graph (CG) with PointsTo nodes.

   ideal_nodes.map(C->live_nodes(), NULL);  // preallocate space

   // Initialize worklist

   if (C->root() != NULL) {

     ideal_nodes.push(C->root());

   }

   // Processed ideal nodes are unique on ideal_nodes list

   // but several ideal nodes are mapped to the phantom_obj.

   // To avoid duplicated entries on the following worklists

   // add the phantom_obj only once to them.

   ptnodes_worklist.append(phantom_obj);

   java_objects_worklist.append(phantom_obj);

   for( uint next = 0; next < ideal_nodes.size(); ++next ) {

     Node* n = ideal_nodes.at(next);

     // Create PointsTo nodes and add them to Connection Graph. Called

     // only once per ideal node since ideal_nodes is Unique_Node list.

     add_node_to_connection_graph(n, &delayed_worklist);

     PointsToNode* ptn = ptnode_adr(n->_idx);

     if (ptn != NULL && ptn != phantom_obj) {

       ptnodes_worklist.append(ptn);

       if (ptn->is_JavaObject()) {

         java_objects_worklist.append(ptn->as_JavaObject());

         if ((n->is_Allocate() || n->is_CallStaticJava()) &&

             (ptn->escape_state() < PointsToNode::GlobalEscape)) {

           // Only allocations and java static calls results are interesting.

           non_escaped_worklist.append(ptn->as_JavaObject());

         }

       } else if (ptn->is_Field() && ptn->as_Field()->is_oop()) {

         oop_fields_worklist.append(ptn->as_Field());

       }

     }

     if (n->is_MergeMem()) {

       // Collect all MergeMem nodes to add memory slices for

       // scalar replaceable objects in split_unique_types().

       _mergemem_worklist.append(n->as_MergeMem());

     } else if (OptimizePtrCompare && n->is_Cmp() &&

                (n->Opcode() == Op_CmpP || n->Opcode() == Op_CmpN)) {

       // Collect compare pointers nodes.

       ptr_cmp_worklist.append(n);

     } else if (n->is_MemBarStoreStore()) {

       // Collect all MemBarStoreStore nodes so that depending on the

       // escape status of the associated Allocate node some of them

       // may be eliminated.

       storestore_worklist.append(n);

     } else if (n->is_MemBar() && (n->Opcode() == Op_MemBarRelease) &&

                (n->req() > MemBarNode::Precedent)) {

       record_for_optimizer(n);

 #ifdef ASSERT

     } else if (n->is_AddP()) {

       // Collect address nodes for graph verification.

       addp_worklist.append(n);

 #endif

     }

     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {

       Node* m = n->fast_out(i);   // Get user

       ideal_nodes.push(m);

     }

   }

   if (non_escaped_worklist.length() == 0) {

     _collecting = false;

     return false; // Nothing to do.

   }

   // Add final simple edges to graph.

   while(delayed_worklist.size() > 0) {

     Node* n = delayed_worklist.pop();

     add_final_edges(n);

   }

   int ptnodes_length = ptnodes_worklist.length();

 #ifdef ASSERT

   if (VerifyConnectionGraph) {

     // Verify that no new simple edges could be created and all

     // local vars has edges.

     _verify = true;

     for (int next = 0; next < ptnodes_length; ++next) {

       PointsToNode* ptn = ptnodes_worklist.at(next);

       add_final_edges(ptn->ideal_node());

       if (ptn->is_LocalVar() && ptn->edge_count() == 0) {

         ptn->dump();

         assert(ptn->as_LocalVar()->edge_count() > 0, "sanity");

       }

     }

     _verify = false;

   }

 #endif

   // Bytecode analyzer BCEscapeAnalyzer, used for Call nodes

   // processing, calls to CI to resolve symbols (types, fields, methods)

   // referenced in bytecode. During symbol resolution VM may throw

   // an exception which CI cleans and converts to compilation failure.

   if (C->failing())  return false;

   // 2. Finish Graph construction by propagating references to all

   //    java objects through graph.

   if (!complete_connection_graph(ptnodes_worklist, non_escaped_worklist,

                                  java_objects_worklist, oop_fields_worklist)) {

     // All objects escaped or hit time or iterations limits.

     _collecting = false;

     return false;

   }

   // 3. Adjust scalar_replaceable state of nonescaping objects and push

   //    scalar replaceable allocations on alloc_worklist for processing

   //    in split_unique_types().

   int non_escaped_length = non_escaped_worklist.length();

   for (int next = 0; next < non_escaped_length; next++) {

     JavaObjectNode* ptn = non_escaped_worklist.at(next);

     bool noescape = (ptn->escape_state() == PointsToNode::NoEscape);

     Node* n = ptn->ideal_node();

     if (n->is_Allocate()) {

       n->as_Allocate()->_is_non_escaping = noescape;

     }

     if (n->is_CallStaticJava()) {

       n->as_CallStaticJava()->_is_non_escaping = noescape;

     }

     if (noescape && ptn->scalar_replaceable()) {

       adjust_scalar_replaceable_state(ptn);

       if (ptn->scalar_replaceable()) {

         alloc_worklist.append(ptn->ideal_node());

       }

     }

   }

 #ifdef ASSERT

   if (VerifyConnectionGraph) {

     // Verify that graph is complete - no new edges could be added or needed.

     verify_connection_graph(ptnodes_worklist, non_escaped_worklist,

                             java_objects_worklist, addp_worklist);

   }

   assert(C->unique() == nodes_size(), "no new ideal nodes should be added during ConnectionGraph build");

   assert(null_obj->escape_state() == PointsToNode::NoEscape &&

          null_obj->edge_count() == 0 &&

          !null_obj->arraycopy_src() &&

          !null_obj->arraycopy_dst(), "sanity");

 #endif

   _collecting = false;

   } // TracePhase t3("connectionGraph")

   // 4. Optimize ideal graph based on EA information.

   bool has_non_escaping_obj = (non_escaped_worklist.length() > 0);

   if (has_non_escaping_obj) {

     optimize_ideal_graph(ptr_cmp_worklist, storestore_worklist);

   }

 #ifndef PRODUCT

   if (PrintEscapeAnalysis) {

     dump(ptnodes_worklist); // Dump ConnectionGraph

   }

 #endif

   bool has_scalar_replaceable_candidates = (alloc_worklist.length() > 0);

 #ifdef ASSERT

   if (VerifyConnectionGraph) {

     int alloc_length = alloc_worklist.length();

     for (int next = 0; next < alloc_length; ++next) {

       Node* n = alloc_worklist.at(next);

       PointsToNode* ptn = ptnode_adr(n->_idx);

       assert(ptn->escape_state() == PointsToNode::NoEscape && ptn->scalar_replaceable(), "sanity");

     }

   }

 #endif

   // 5. Separate memory graph for scalar replaceable allcations.

   if (has_scalar_replaceable_candidates &&

       C->AliasLevel() >= 3 && EliminateAllocations) {

     // Now use the escape information to create unique types for

     // scalar replaceable objects.

     split_unique_types(alloc_worklist);

     if (C->failing())  return false;

     C->print_method(PHASE_AFTER_EA, 2);

 #ifdef ASSERT

   } else if (Verbose && (PrintEscapeAnalysis || PrintEliminateAllocations)) {

     tty->print("=== No allocations eliminated for ");

     C->method()->print_short_name();

     if(!EliminateAllocations) {

       tty->print(" since EliminateAllocations is off ===");

     } else if(!has_scalar_replaceable_candidates) {

       tty->print(" since there are no scalar replaceable candidates ===");

     } else if(C->AliasLevel() < 3) {

       tty->print(" since AliasLevel < 3 ===");

     }

     tty->cr();

 #endif

   }

   return has_non_escaping_obj;

 }

 // Utility function for nodes that load an object

 void ConnectionGraph::add_objload_to_connection_graph(Node *n, Unique_Node_List *delayed_worklist) {

   // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because

   // ThreadLocal has RawPtr type.

   const Type* t = _igvn->type(n);

   if (t->make_ptr() != NULL) {

     Node* adr = n->in(MemNode::Address);

 #ifdef ASSERT

     if (!adr->is_AddP()) {

       assert(_igvn->type(adr)->isa_rawptr(), "sanity");

     } else {

       assert((ptnode_adr(adr->_idx) == NULL ||

               ptnode_adr(adr->_idx)->as_Field()->is_oop()), "sanity");

     }

 #endif

     add_local_var_and_edge(n, PointsToNode::NoEscape,

                            adr, delayed_worklist);

   }

 }

 // Populate Connection Graph with PointsTo nodes and create simple

 // connection graph edges.

 void ConnectionGraph::add_node_to_connection_graph(Node *n, Unique_Node_List *delayed_worklist) {

   assert(!_verify, "this method sould not be called for verification");

   PhaseGVN* igvn = _igvn;

   uint n_idx = n->_idx;

   PointsToNode* n_ptn = ptnode_adr(n_idx);

   if (n_ptn != NULL)

     return; // No need to redefine PointsTo node during first iteration.

   if (n->is_Call()) {

     // Arguments to allocation and locking don't escape.

     if (n->is_AbstractLock()) {

       // Put Lock and Unlock nodes on IGVN worklist to process them during

       // first IGVN optimization when escape information is still available.

       record_for_optimizer(n);

     } else if (n->is_Allocate()) {

       add_call_node(n->as_Call());

       record_for_optimizer(n);

     } else {

       if (n->is_CallStaticJava()) {

         const char* name = n->as_CallStaticJava()->_name;

         if (name != NULL && strcmp(name, "uncommon_trap") == 0)

           return; // Skip uncommon traps

       }

       // Don't mark as processed since call's arguments have to be processed.

       delayed_worklist->push(n);

       // Check if a call returns an object.

       if ((n->as_Call()->returns_pointer() &&

            n->as_Call()->proj_out(TypeFunc::Parms) != NULL) ||

           (n->is_CallStaticJava() &&

            n->as_CallStaticJava()->is_boxing_method())) {

         add_call_node(n->as_Call());

       }

     }

     return;

   }

   // Put this check here to process call arguments since some call nodes

   // point to phantom_obj.

   if (n_ptn == phantom_obj || n_ptn == null_obj)

     return; // Skip predefined nodes.

   int opcode = n->Opcode();

   switch (opcode) {

     case Op_AddP: {

       Node* base = get_addp_base(n);

       PointsToNode* ptn_base = ptnode_adr(base->_idx);

       // Field nodes are created for all field types. They are used in

       // adjust_scalar_replaceable_state() and split_unique_types().

       // Note, non-oop fields will have only base edges in Connection

       // Graph because such fields are not used for oop loads and stores.

       int offset = address_offset(n, igvn);

       add_field(n, PointsToNode::NoEscape, offset);

       if (ptn_base == NULL) {

         delayed_worklist->push(n); // Process it later.

       } else {

         n_ptn = ptnode_adr(n_idx);

         add_base(n_ptn->as_Field(), ptn_base);

       }

       break;

     }

     case Op_CastX2P: {

       map_ideal_node(n, phantom_obj);

       break;

     }

     case Op_CastPP:

     case Op_CheckCastPP:

     case Op_EncodeP:

     case Op_DecodeN:

     case Op_EncodePKlass:

     case Op_DecodeNKlass: {

       add_local_var_and_edge(n, PointsToNode::NoEscape,

                              n->in(1), delayed_worklist);

       break;

     }

     case Op_CMoveP: {

       add_local_var(n, PointsToNode::NoEscape);

       // Do not add edges during first iteration because some could be

       // not defined yet.

       delayed_worklist->push(n);

       break;

     }

     case Op_ConP:

     case Op_ConN:

     case Op_ConNKlass: {

       // assume all oop constants globally escape except for null

       PointsToNode::EscapeState es;

       const Type* t = igvn->type(n);

       if (t == TypePtr::NULL_PTR || t == TypeNarrowOop::NULL_PTR) {

         es = PointsToNode::NoEscape;

       } else {

         es = PointsToNode::GlobalEscape;

       }

       add_java_object(n, es);

       break;

     }

     case Op_CreateEx: {

       // assume that all exception objects globally escape

       map_ideal_node(n, phantom_obj);

       break;

     }

     case Op_LoadKlass:

     case Op_LoadNKlass: {

       // Unknown class is loaded

       map_ideal_node(n, phantom_obj);

       break;

     }

     case Op_LoadP:

     case Op_LoadN:

     case Op_LoadPLocked: {

       add_objload_to_connection_graph(n, delayed_worklist);

       break;

     }

     case Op_Parm: {

       map_ideal_node(n, phantom_obj);

       break;

     }

     case Op_PartialSubtypeCheck: {

       // Produces Null or notNull and is used in only in CmpP so

       // phantom_obj could be used.

       map_ideal_node(n, phantom_obj); // Result is unknown

       break;

     }

     case Op_Phi: {

       // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because

       // ThreadLocal has RawPtr type.

       const Type* t = n->as_Phi()->type();

       if (t->make_ptr() != NULL) {

         add_local_var(n, PointsToNode::NoEscape);

         // Do not add edges during first iteration because some could be

         // not defined yet.

         delayed_worklist->push(n);

       }

       break;

     }

     case Op_Proj: {

       // we are only interested in the oop result projection from a call

       if (n->as_Proj()->_con == TypeFunc::Parms && n->in(0)->is_Call() &&

           n->in(0)->as_Call()->returns_pointer()) {

         add_local_var_and_edge(n, PointsToNode::NoEscape,

                                n->in(0), delayed_worklist);

       }

       break;

     }

     case Op_Rethrow: // Exception object escapes

     case Op_Return: {

       if (n->req() > TypeFunc::Parms &&

           igvn->type(n->in(TypeFunc::Parms))->isa_oopptr()) {

         // Treat Return value as LocalVar with GlobalEscape escape state.

         add_local_var_and_edge(n, PointsToNode::GlobalEscape,

                                n->in(TypeFunc::Parms), delayed_worklist);

       }

       break;

     }

     case Op_GetAndSetP:

     case Op_GetAndSetN: {

       add_objload_to_connection_graph(n, delayed_worklist);

       // fallthrough

     }

     case Op_StoreP:

     case Op_StoreN:

     case Op_StoreNKlass:

     case Op_StorePConditional:

     case Op_CompareAndSwapP:

     case Op_CompareAndSwapN: {

       Node* adr = n->in(MemNode::Address);

       const Type *adr_type = igvn->type(adr);

       adr_type = adr_type->make_ptr();

       if (adr_type == NULL) {

         break; // skip dead nodes

       }

       if (adr_type->isa_oopptr() ||

           (opcode == Op_StoreP || opcode == Op_StoreN || opcode == Op_StoreNKlass) &&

                         (adr_type == TypeRawPtr::NOTNULL &&

                          adr->in(AddPNode::Address)->is_Proj() &&

                          adr->in(AddPNode::Address)->in(0)->is_Allocate())) {

         delayed_worklist->push(n); // Process it later.

 #ifdef ASSERT

         assert(adr->is_AddP(), "expecting an AddP");

         if (adr_type == TypeRawPtr::NOTNULL) {

           // Verify a raw address for a store captured by Initialize node.

           int offs = (int)igvn->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);

           assert(offs != Type::OffsetBot, "offset must be a constant");

         }

 #endif

       } else {

         // Ignore copy the displaced header to the BoxNode (OSR compilation).

         if (adr->is_BoxLock())

           break;

         // Stored value escapes in unsafe access.

         if ((opcode == Op_StoreP) && (adr_type == TypeRawPtr::BOTTOM)) {

           // Pointer stores in G1 barriers looks like unsafe access.

           // Ignore such stores to be able scalar replace non-escaping

           // allocations.

           if (UseG1GC && adr->is_AddP()) {

             Node* base = get_addp_base(adr);

             if (base->Opcode() == Op_LoadP &&

                 base->in(MemNode::Address)->is_AddP()) {

               adr = base->in(MemNode::Address);

               Node* tls = get_addp_base(adr);

               if (tls->Opcode() == Op_ThreadLocal) {

                 int offs = (int)igvn->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);

                 if (offs == in_bytes(JavaThread::satb_mark_queue_offset() +

                                      PtrQueue::byte_offset_of_buf())) {

                   break; // G1 pre barier previous oop value store.

                 }

                 if (offs == in_bytes(JavaThread::dirty_card_queue_offset() +

                                      PtrQueue::byte_offset_of_buf())) {

                   break; // G1 post barier card address store.

                 }

               }

             }

           }

           delayed_worklist->push(n); // Process unsafe access later.

           break;

         }

 #ifdef ASSERT

         n->dump(1);

         assert(false, "not unsafe or G1 barrier raw StoreP");

 #endif

       }

       break;

     }

     case Op_AryEq:

     case Op_StrComp:

     case Op_StrEquals:

     case Op_StrIndexOf:

     case Op_EncodeISOArray: {

       add_local_var(n, PointsToNode::ArgEscape);

       delayed_worklist->push(n); // Process it later.

       break;

     }

     case Op_ThreadLocal: {

       add_java_object(n, PointsToNode::ArgEscape);

       break;

     }

     default:

       ; // Do nothing for nodes not related to EA.

   }

   return;

 }

 #ifdef ASSERT

 #define ELSE_FAIL(name)                               \

       /* Should not be called for not pointer type. */  \

       n->dump(1);                                       \

       assert(false, name);                              \

       break;

 #else

 #define ELSE_FAIL(name) \

       break;

 #endif

 // Add final simple edges to graph.

 void ConnectionGraph::add_final_edges(Node *n) {

   PointsToNode* n_ptn = ptnode_adr(n->_idx);

 #ifdef ASSERT

   if (_verify && n_ptn->is_JavaObject())

     return; // This method does not change graph for JavaObject.

 #endif

   if (n->is_Call()) {

     process_call_arguments(n->as_Call());

     return;

   }

   assert(n->is_Store() || n->is_LoadStore() ||

          (n_ptn != NULL) && (n_ptn->ideal_node() != NULL),

          "node should be registered already");

   int opcode = n->Opcode();

   switch (opcode) {

     case Op_AddP: {

       Node* base = get_addp_base(n);

       PointsToNode* ptn_base = ptnode_adr(base->_idx);

       assert(ptn_base != NULL, "field's base should be registered");

       add_base(n_ptn->as_Field(), ptn_base);

       break;

     }

     case Op_CastPP:

     case Op_CheckCastPP:

     case Op_EncodeP:

     case Op_DecodeN:

     case Op_EncodePKlass:

     case Op_DecodeNKlass: {

       add_local_var_and_edge(n, PointsToNode::NoEscape,

                              n->in(1), NULL);

       break;

     }

     case Op_CMoveP: {

       for (uint i = CMoveNode::IfFalse; i < n->req(); i++) {

         Node* in = n->in(i);

         if (in == NULL)

           continue;  // ignore NULL

         Node* uncast_in = in->uncast();

         if (uncast_in->is_top() || uncast_in == n)

           continue;  // ignore top or inputs which go back this node

         PointsToNode* ptn = ptnode_adr(in->_idx);

         assert(ptn != NULL, "node should be registered");

         add_edge(n_ptn, ptn);

       }

       break;

     }

     case Op_LoadP:

     case Op_LoadN:

     case Op_LoadPLocked: {

       // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because

       // ThreadLocal has RawPtr type.

       const Type* t = _igvn->type(n);

       if (t->make_ptr() != NULL) {

         Node* adr = n->in(MemNode::Address);

         add_local_var_and_edge(n, PointsToNode::NoEscape, adr, NULL);

         break;

       }

       ELSE_FAIL("Op_LoadP");

     }

     case Op_Phi: {

       // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because

       // ThreadLocal has RawPtr type.

       const Type* t = n->as_Phi()->type();

       if (t->make_ptr() != NULL) {

         for (uint i = 1; i < n->req(); i++) {

           Node* in = n->in(i);

           if (in == NULL)

             continue;  // ignore NULL

           Node* uncast_in = in->uncast();

           if (uncast_in->is_top() || uncast_in == n)

             continue;  // ignore top or inputs which go back this node

           PointsToNode* ptn = ptnode_adr(in->_idx);

           assert(ptn != NULL, "node should be registered");

           add_edge(n_ptn, ptn);

         }

         break;

       }

       ELSE_FAIL("Op_Phi");

     }

     case Op_Proj: {

       // we are only interested in the oop result projection from a call

       if (n->as_Proj()->_con == TypeFunc::Parms && n->in(0)->is_Call() &&

           n->in(0)->as_Call()->returns_pointer()) {

         add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(0), NULL);

         break;

       }

       ELSE_FAIL("Op_Proj");

     }

     case Op_Rethrow: // Exception object escapes

     case Op_Return: {

       if (n->req() > TypeFunc::Parms &&

           _igvn->type(n->in(TypeFunc::Parms))->isa_oopptr()) {

         // Treat Return value as LocalVar with GlobalEscape escape state.

         add_local_var_and_edge(n, PointsToNode::GlobalEscape,

                                n->in(TypeFunc::Parms), NULL);

         break;

       }

       ELSE_FAIL("Op_Return");

     }

     case Op_StoreP:

     case Op_StoreN:

     case Op_StoreNKlass:

     case Op_StorePConditional:

     case Op_CompareAndSwapP:

     case Op_CompareAndSwapN:

     case Op_GetAndSetP:

     case Op_GetAndSetN: {

       Node* adr = n->in(MemNode::Address);

       const Type *adr_type = _igvn->type(adr);

       adr_type = adr_type->make_ptr();

 #ifdef ASSERT

       if (adr_type == NULL) {

         n->dump(1);

         assert(adr_type != NULL, "dead node should not be on list");

         break;

       }

 #endif

       if (opcode == Op_GetAndSetP || opcode == Op_GetAndSetN) {

         add_local_var_and_edge(n, PointsToNode::NoEscape, adr, NULL);

       }

       if (adr_type->isa_oopptr() ||

           (opcode == Op_StoreP || opcode == Op_StoreN || opcode == Op_StoreNKlass) &&

                         (adr_type == TypeRawPtr::NOTNULL &&

                          adr->in(AddPNode::Address)->is_Proj() &&

                          adr->in(AddPNode::Address)->in(0)->is_Allocate())) {

         // Point Address to Value

         PointsToNode* adr_ptn = ptnode_adr(adr->_idx);

         assert(adr_ptn != NULL &&

                adr_ptn->as_Field()->is_oop(), "node should be registered");

         Node *val = n->in(MemNode::ValueIn);

         PointsToNode* ptn = ptnode_adr(val->_idx);

         assert(ptn != NULL, "node should be registered");

         add_edge(adr_ptn, ptn);

         break;

       } else if ((opcode == Op_StoreP) && (adr_type == TypeRawPtr::BOTTOM)) {

         // Stored value escapes in unsafe access.

         Node *val = n->in(MemNode::ValueIn);

         PointsToNode* ptn = ptnode_adr(val->_idx);

         assert(ptn != NULL, "node should be registered");

         set_escape_state(ptn, PointsToNode::GlobalEscape);

         // Add edge to object for unsafe access with offset.

         PointsToNode* adr_ptn = ptnode_adr(adr->_idx);

         assert(adr_ptn != NULL, "node should be registered");

         if (adr_ptn->is_Field()) {

           assert(adr_ptn->as_Field()->is_oop(), "should be oop field");

           add_edge(adr_ptn, ptn);

         }

         break;

       }

       ELSE_FAIL("Op_StoreP");

     }

     case Op_AryEq:

     case Op_StrComp:

     case Op_StrEquals:

     case Op_StrIndexOf:

     case Op_EncodeISOArray: {

       // char[] arrays passed to string intrinsic do not escape but

       // they are not scalar replaceable. Adjust escape state for them.

       // Start from in(2) edge since in(1) is memory edge.

       for (uint i = 2; i < n->req(); i++) {

         Node* adr = n->in(i);

         const Type* at = _igvn->type(adr);

         if (!adr->is_top() && at->isa_ptr()) {

           assert(at == Type::TOP || at == TypePtr::NULL_PTR ||

                  at->isa_ptr() != NULL, "expecting a pointer");

           if (adr->is_AddP()) {

             adr = get_addp_base(adr);

           }

           PointsToNode* ptn = ptnode_adr(adr->_idx);

           assert(ptn != NULL, "node should be registered");

           add_edge(n_ptn, ptn);

         }

       }

       break;

     }

     default: {

       // This method should be called only for EA specific nodes which may

       // miss some edges when they were created.

 #ifdef ASSERT

       n->dump(1);

 #endif

       guarantee(false, "unknown node");

     }

   }

   return;

 }

 void ConnectionGraph::add_call_node(CallNode* call) {

   assert(call->returns_pointer(), "only for call which returns pointer");

   uint call_idx = call->_idx;

   if (call->is_Allocate()) {

     Node* k = call->in(AllocateNode::KlassNode);

     const TypeKlassPtr* kt = k->bottom_type()->isa_klassptr();

     assert(kt != NULL, "TypeKlassPtr  required.");

     ciKlass* cik = kt->klass();

     PointsToNode::EscapeState es = PointsToNode::NoEscape;

     bool scalar_replaceable = true;

     if (call->is_AllocateArray()) {

       if (!cik->is_array_klass()) { // StressReflectiveCode

         es = PointsToNode::GlobalEscape;

       } else {

         int length = call->in(AllocateNode::ALength)->find_int_con(-1);

         if (length < 0 || length > EliminateAllocationArraySizeLimit) {

           // Not scalar replaceable if the length is not constant or too big.

           scalar_replaceable = false;

         }

       }

     } else {  // Allocate instance

       if (cik->is_subclass_of(_compile->env()->Thread_klass()) ||

           cik->is_subclass_of(_compile->env()->Reference_klass()) ||

          !cik->is_instance_klass() || // StressReflectiveCode

           cik->as_instance_klass()->has_finalizer()) {

         es = PointsToNode::GlobalEscape;

       }

     }

     add_java_object(call, es);

     PointsToNode* ptn = ptnode_adr(call_idx);

     if (!scalar_replaceable && ptn->scalar_replaceable()) {

       ptn->set_scalar_replaceable(false);

     }

   } else if (call->is_CallStaticJava()) {

     // Call nodes could be different types:

     //

     // 1. CallDynamicJavaNode (what happened during call is unknown):

     //

     //    - mapped to GlobalEscape JavaObject node if oop is returned;

     //

     //    - all oop arguments are escaping globally;

     //

     // 2. CallStaticJavaNode (execute bytecode analysis if possible):

     //

     //    - the same as CallDynamicJavaNode if can't do bytecode analysis;

     //

     //    - mapped to GlobalEscape JavaObject node if unknown oop is returned;

     //    - mapped to NoEscape JavaObject node if non-escaping object allocated

     //      during call is returned;

     //    - mapped to ArgEscape LocalVar node pointed to object arguments

     //      which are returned and does not escape during call;

     //

     //    - oop arguments escaping status is defined by bytecode analysis;

     //

     // For a static call, we know exactly what method is being called.

     // Use bytecode estimator to record whether the call's return value escapes.

     ciMethod* meth = call->as_CallJava()->method();

     if (meth == NULL) {

       const char* name = call->as_CallStaticJava()->_name;

       assert(strncmp(name, "_multianewarray", 15) == 0, "TODO: add failed case check");

       // Returns a newly allocated unescaped object.

       add_java_object(call, PointsToNode::NoEscape);

       ptnode_adr(call_idx)->set_scalar_replaceable(false);

     } else if (meth->is_boxing_method()) {

       // Returns boxing object

       PointsToNode::EscapeState es;

       vmIntrinsics::ID intr = meth->intrinsic_id();

       if (intr == vmIntrinsics::_floatValue || intr == vmIntrinsics::_doubleValue) {

         // It does not escape if object is always allocated.

         es = PointsToNode::NoEscape;

       } else {

         // It escapes globally if object could be loaded from cache.

         es = PointsToNode::GlobalEscape;

       }

       add_java_object(call, es);

     } else {

       BCEscapeAnalyzer* call_analyzer = meth->get_bcea();

       call_analyzer->copy_dependencies(_compile->dependencies());

       if (call_analyzer->is_return_allocated()) {

         // Returns a newly allocated unescaped object, simply

         // update dependency information.

         // Mark it as NoEscape so that objects referenced by

         // it's fields will be marked as NoEscape at least.

         add_java_object(call, PointsToNode::NoEscape);

         ptnode_adr(call_idx)->set_scalar_replaceable(false);

       } else {

         // Determine whether any arguments are returned.

         const TypeTuple* d = call->tf()->domain();

         bool ret_arg = false;

         for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {

           if (d->field_at(i)->isa_ptr() != NULL &&

               call_analyzer->is_arg_returned(i - TypeFunc::Parms)) {

             ret_arg = true;

             break;

           }

         }

         if (ret_arg) {

           add_local_var(call, PointsToNode::ArgEscape);

         } else {

           // Returns unknown object.

           map_ideal_node(call, phantom_obj);

         }

       }

     }

   } else {

     // An other type of call, assume the worst case:

     // returned value is unknown and globally escapes.

     assert(call->Opcode() == Op_CallDynamicJava, "add failed case check");

     map_ideal_node(call, phantom_obj);

   }

 }

 void ConnectionGraph::process_call_arguments(CallNode *call) {

     bool is_arraycopy = false;

     switch (call->Opcode()) {

 #ifdef ASSERT

     case Op_Allocate:

     case Op_AllocateArray:

     case Op_Lock:

     case Op_Unlock:

       assert(false, "should be done already");

       break;

 #endif

     case Op_CallLeafNoFP:

       is_arraycopy = (call->as_CallLeaf()->_name != NULL &&

                       strstr(call->as_CallLeaf()->_name, "arraycopy") != 0);

       // fall through

     case Op_CallLeaf: {

       // Stub calls, objects do not escape but they are not scale replaceable.

       // Adjust escape state for outgoing arguments.

       const TypeTuple * d = call->tf()->domain();

       bool src_has_oops = false;

       for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {

         const Type* at = d->field_at(i);

         Node *arg = call->in(i);

         const Type *aat = _igvn->type(arg);

         if (arg->is_top() || !at->isa_ptr() || !aat->isa_ptr())

           continue;

         if (arg->is_AddP()) {

           //

           // The inline_native_clone() case when the arraycopy stub is called

           // after the allocation before Initialize and CheckCastPP nodes.

           // Or normal arraycopy for object arrays case.

           //

           // Set AddP's base (Allocate) as not scalar replaceable since

           // pointer to the base (with offset) is passed as argument.

           //

           arg = get_addp_base(arg);

         }

         PointsToNode* arg_ptn = ptnode_adr(arg->_idx);

         assert(arg_ptn != NULL, "should be registered");

         PointsToNode::EscapeState arg_esc = arg_ptn->escape_state();

         if (is_arraycopy || arg_esc < PointsToNode::ArgEscape) {

           assert(aat == Type::TOP || aat == TypePtr::NULL_PTR ||

                  aat->isa_ptr() != NULL, "expecting an Ptr");

           bool arg_has_oops = aat->isa_oopptr() &&

                               (aat->isa_oopptr()->klass() == NULL || aat->isa_instptr() ||

                                (aat->isa_aryptr() && aat->isa_aryptr()->klass()->is_obj_array_klass()));

           if (i == TypeFunc::Parms) {

             src_has_oops = arg_has_oops;

           }

           //

           // src or dst could be j.l.Object when other is basic type array:

           //

           //   arraycopy(char[],0,Object*,0,size);

           //   arraycopy(Object*,0,char[],0,size);

           //

           // Don't add edges in such cases.

           //

           bool arg_is_arraycopy_dest = src_has_oops && is_arraycopy &&

                                        arg_has_oops && (i > TypeFunc::Parms);

 #ifdef ASSERT

           if (!(is_arraycopy ||

                 (call->as_CallLeaf()->_name != NULL &&

                  (strcmp(call->as_CallLeaf()->_name, "g1_wb_pre")  == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "g1_wb_post") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "updateBytesCRC32") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "aescrypt_encryptBlock") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "aescrypt_decryptBlock") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "cipherBlockChaining_encryptAESCrypt") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "cipherBlockChaining_decryptAESCrypt") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "sha1_implCompress") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "sha1_implCompressMB") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "sha256_implCompress") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "sha256_implCompressMB") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "sha512_implCompress") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "sha512_implCompressMB") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "multiplyToLen") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "squareToLen") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "mulAdd") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "montgomery_multiply") == 0 ||

                   strcmp(call->as_CallLeaf()->_name, "montgomery_square") == 0)

                  ))) {

             call->dump();

             fatal(err_msg_res("EA unexpected CallLeaf %s", call->as_CallLeaf()->_name));

           }

 #endif

           // Always process arraycopy's destination object since

           // we need to add all possible edges to references in

           // source object.

           if (arg_esc >= PointsToNode::ArgEscape &&

               !arg_is_arraycopy_dest) {

             continue;

           }

           set_escape_state(arg_ptn, PointsToNode::ArgEscape);

           if (arg_is_arraycopy_dest) {

             Node* src = call->in(TypeFunc::Parms);

             if (src->is_AddP()) {

               src = get_addp_base(src);

             }

             PointsToNode* src_ptn = ptnode_adr(src->_idx);

             assert(src_ptn != NULL, "should be registered");

             if (arg_ptn != src_ptn) {

               // Special arraycopy edge:

               // A destination object's field can't have the source object

               // as base since objects escape states are not related.

               // Only escape state of destination object's fields affects

               // escape state of fields in source object.

               add_arraycopy(call, PointsToNode::ArgEscape, src_ptn, arg_ptn);

             }

           }

         }

       }

       break;

     }

     case Op_CallStaticJava: {

       // For a static call, we know exactly what method is being called.

       // Use bytecode estimator to record the call's escape affects

 #ifdef ASSERT

       const char* name = call->as_CallStaticJava()->_name;

       assert((name == NULL || strcmp(name, "uncommon_trap") != 0), "normal calls only");

 #endif

       ciMethod* meth = call->as_CallJava()->method();

       if ((meth != NULL) && meth->is_boxing_method()) {

         break; // Boxing methods do not modify any oops.

       }

       BCEscapeAnalyzer* call_analyzer = (meth !=NULL) ? meth->get_bcea() : NULL;

       // fall-through if not a Java method or no analyzer information

       if (call_analyzer != NULL) {

         PointsToNode* call_ptn = ptnode_adr(call->_idx);

         const TypeTuple* d = call->tf()->domain();

         for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {

           const Type* at = d->field_at(i);

           int k = i - TypeFunc::Parms;

           Node* arg = call->in(i);

           PointsToNode* arg_ptn = ptnode_adr(arg->_idx);

           if (at->isa_ptr() != NULL &&

               call_analyzer->is_arg_returned(k)) {

             // The call returns arguments.

             if (call_ptn != NULL) { // Is call's result used?

               assert(call_ptn->is_LocalVar(), "node should be registered");

               assert(arg_ptn != NULL, "node should be registered");

               add_edge(call_ptn, arg_ptn);

             }

           }

           if (at->isa_oopptr() != NULL &&

               arg_ptn->escape_state() < PointsToNode::GlobalEscape) {

             if (!call_analyzer->is_arg_stack(k)) {

               // The argument global escapes

               set_escape_state(arg_ptn, PointsToNode::GlobalEscape);

             } else {

               set_escape_state(arg_ptn, PointsToNode::ArgEscape);

               if (!call_analyzer->is_arg_local(k)) {

                 // The argument itself doesn't escape, but any fields might

                 set_fields_escape_state(arg_ptn, PointsToNode::GlobalEscape);

               }

             }

           }

         }

         if (call_ptn != NULL && call_ptn->is_LocalVar()) {

           // The call returns arguments.

           assert(call_ptn->edge_count() > 0, "sanity");

           if (!call_analyzer->is_return_local()) {

             // Returns also unknown object.

             add_edge(call_ptn, phantom_obj);

           }

         }

         break;

       }

     }

     default: {

       // Fall-through here if not a Java method or no analyzer information

       // or some other type of call, assume the worst case: all arguments

       // globally escape.

       const TypeTuple* d = call->tf()->domain();

       for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {

         const Type* at = d->field_at(i);

         if (at->isa_oopptr() != NULL) {

           Node* arg = call->in(i);

           if (arg->is_AddP()) {

             arg = get_addp_base(arg);

           }

           assert(ptnode_adr(arg->_idx) != NULL, "should be defined already");

           set_escape_state(ptnode_adr(arg->_idx), PointsToNode::GlobalEscape);

         }

       }

     }

   }

 }

 // Finish Graph construction.

 bool ConnectionGraph::complete_connection_graph(

                          GrowableArray<PointsToNode*>&   ptnodes_worklist,

                          GrowableArray<JavaObjectNode*>& non_escaped_worklist,

                          GrowableArray<JavaObjectNode*>& java_objects_worklist,

                          GrowableArray<FieldNode*>&      oop_fields_worklist) {

   // Normally only 1-3 passes needed to build Connection Graph depending

   // on graph complexity. Observed 8 passes in jvm2008 compiler.compiler.

   // Set limit to 20 to catch situation when something did go wrong and

   // bailout Escape Analysis.

   // Also limit build time to 20 sec (60 in debug VM), EscapeAnalysisTimeout flag.

 #define CG_BUILD_ITER_LIMIT 20

   // Propagate GlobalEscape and ArgEscape escape states and check that

   // we still have non-escaping objects. The method pushs on _worklist

   // Field nodes which reference phantom_object.

   if (!find_non_escaped_objects(ptnodes_worklist, non_escaped_worklist)) {

     return false; // Nothing to do.

   }

   // Now propagate references to all JavaObject nodes.

   int java_objects_length = java_objects_worklist.length();

   elapsedTimer time;

   bool timeout = false;

   int new_edges = 1;

   int iterations = 0;

   do {

     while ((new_edges > 0) &&

            (iterations++ < CG_BUILD_ITER_LIMIT)) {

       double start_time = time.seconds();

       time.start();

       new_edges = 0;

       // Propagate references to phantom_object for nodes pushed on _worklist

       // by find_non_escaped_objects() and find_field_value().

       new_edges += add_java_object_edges(phantom_obj, false);

       for (int next = 0; next < java_objects_length; ++next) {

         JavaObjectNode* ptn = java_objects_worklist.at(next);

         new_edges += add_java_object_edges(ptn, true);

 #define SAMPLE_SIZE 4

         if ((next % SAMPLE_SIZE) == 0) {

           // Each 4 iterations calculate how much time it will take

           // to complete graph construction.

           time.stop();

           // Poll for requests from shutdown mechanism to quiesce compiler

           // because Connection graph construction may take long time.

           CompileBroker::maybe_block();

           double stop_time = time.seconds();

           double time_per_iter = (stop_time - start_time) / (double)SAMPLE_SIZE;

           double time_until_end = time_per_iter * (double)(java_objects_length - next);

           if ((start_time + time_until_end) >= EscapeAnalysisTimeout) {

             timeout = true;

             break; // Timeout

           }

           start_time = stop_time;

           time.start();

         }

 #undef SAMPLE_SIZE

       }

       if (timeout) break;

       if (new_edges > 0) {

         // Update escape states on each iteration if graph was updated.

         if (!find_non_escaped_objects(ptnodes_worklist, non_escaped_worklist)) {

           return false; // Nothing to do.

         }

       }

       time.stop();

       if (time.seconds() >= EscapeAnalysisTimeout) {

         timeout = true;

         break;

       }

     }

     if ((iterations < CG_BUILD_ITER_LIMIT) && !timeout) {

       time.start();

       // Find fields which have unknown value.

       int fields_length = oop_fields_worklist.length();

       for (int next = 0; next < fields_length; next++) {

         FieldNode* field = oop_fields_worklist.at(next);

         if (field->edge_count() == 0) {

           new_edges += find_field_value(field);

           // This code may added new edges to phantom_object.

           // Need an other cycle to propagate references to phantom_object.

         }

       }

       time.stop();

       if (time.seconds() >= EscapeAnalysisTimeout) {

         timeout = true;

         break;

       }

     } else {

       new_edges = 0; // Bailout

     }

   } while (new_edges > 0);

   // Bailout if passed limits.

   if ((iterations >= CG_BUILD_ITER_LIMIT) || timeout) {

     Compile* C = _compile;

     if (C->log() != NULL) {

       C->log()->begin_elem("connectionGraph_bailout reason='reached ");

       C->log()->text("%s", timeout ? "time" : "iterations");

       C->log()->end_elem(" limit'");

     }

     assert(ExitEscapeAnalysisOnTimeout, err_msg_res("infinite EA connection graph build (%f sec, %d iterations) with %d nodes and worklist size %d",

            time.seconds(), iterations, nodes_size(), ptnodes_worklist.length()));

     // Possible infinite build_connection_graph loop,

     // bailout (no changes to ideal graph were made).

     return false;

   }

 #ifdef ASSERT

   if (Verbose && PrintEscapeAnalysis) {

     tty->print_cr("EA: %d iterations to build connection graph with %d nodes and worklist size %d",

                   iterations, nodes_size(), ptnodes_worklist.length());

   }

 #endif

 #undef CG_BUILD_ITER_LIMIT

   // Find fields initialized by NULL for non-escaping Allocations.

   int non_escaped_length = non_escaped_worklist.length();

   for (int next = 0; next < non_escaped_length; next++) {

     JavaObjectNode* ptn = non_escaped_worklist.at(next);

     PointsToNode::EscapeState es = ptn->escape_state();

     assert(es <= PointsToNode::ArgEscape, "sanity");

     if (es == PointsToNode::NoEscape) {

       if (find_init_values(ptn, null_obj, _igvn) > 0) {

         // Adding references to NULL object does not change escape states

         // since it does not escape. Also no fields are added to NULL object.

         add_java_object_edges(null_obj, false);

       }

     }

     Node* n = ptn->ideal_node();

     if (n->is_Allocate()) {

       // The object allocated by this Allocate node will never be

       // seen by an other thread. Mark it so that when it is

       // expanded no MemBarStoreStore is added.

       InitializeNode* ini = n->as_Allocate()->initialization();

       if (ini != NULL)

         ini->set_does_not_escape();

     }

   }

   return true; // Finished graph construction.

 }

 // Propagate GlobalEscape and ArgEscape escape states to all nodes

 // and check that we still have non-escaping java objects.

 bool ConnectionGraph::find_non_escaped_objects(GrowableArray<PointsToNode*>& ptnodes_worklist,

                                                GrowableArray<JavaObjectNode*>& non_escaped_worklist) {

   GrowableArray<PointsToNode*> escape_worklist;

   // First, put all nodes with GlobalEscape and ArgEscape states on worklist.

   int ptnodes_length = ptnodes_worklist.length();

   for (int next = 0; next < ptnodes_length; ++next) {

     PointsToNode* ptn = ptnodes_worklist.at(next);

     if (ptn->escape_state() >= PointsToNode::ArgEscape ||

         ptn->fields_escape_state() >= PointsToNode::ArgEscape) {

       escape_worklist.push(ptn);

     }

   }

   // Set escape states to referenced nodes (edges list).

   while (escape_worklist.length() > 0) {

     PointsToNode* ptn = escape_worklist.pop();

     PointsToNode::EscapeState es  = ptn->escape_state();

     PointsToNode::EscapeState field_es = ptn->fields_escape_state();

     if (ptn->is_Field() && ptn->as_Field()->is_oop() &&

         es >= PointsToNode::ArgEscape) {

       // GlobalEscape or ArgEscape state of field means it has unknown value.

       if (add_edge(ptn, phantom_obj)) {

         // New edge was added

         add_field_uses_to_worklist(ptn->as_Field());

       }

     }

     for (EdgeIterator i(ptn); i.has_next(); i.next()) {

       PointsToNode* e = i.get();

       if (e->is_Arraycopy()) {

         assert(ptn->arraycopy_dst(), "sanity");

         // Propagate only fields escape state through arraycopy edge.

         if (e->fields_escape_state() < field_es) {

           set_fields_escape_state(e, field_es);

           escape_worklist.push(e);

         }

       } else if (es >= field_es) {

         // fields_escape_state is also set to 'es' if it is less than 'es'.

         if (e->escape_state() < es) {

           set_escape_state(e, es);

           escape_worklist.push(e);

         }

       } else {

         // Propagate field escape state.

         bool es_changed = false;

         if (e->fields_escape_state() < field_es) {

           set_fields_escape_state(e, field_es);

           es_changed = true;

         }

         if ((e->escape_state() < field_es) &&

             e->is_Field() && ptn->is_JavaObject() &&

             e->as_Field()->is_oop()) {

           // Change escape state of referenced fileds.

           set_escape_state(e, field_es);

           es_changed = true;;

         } else if (e->escape_state() < es) {

           set_escape_state(e, es);

           es_changed = true;;

         }

         if (es_changed) {

           escape_worklist.push(e);

         }

       }

     }

   }

   // Remove escaped objects from non_escaped list.

   for (int next = non_escaped_worklist.length()-1; next >= 0 ; --next) {

     JavaObjectNode* ptn = non_escaped_worklist.at(next);

     if (ptn->escape_state() >= PointsToNode::GlobalEscape) {

       non_escaped_worklist.delete_at(next);

     }

     if (ptn->escape_state() == PointsToNode::NoEscape) {

       // Find fields in non-escaped allocations which have unknown value.

       find_init_values(ptn, phantom_obj, NULL);

     }

   }

   return (non_escaped_worklist.length() > 0);

 }

 // Add all references to JavaObject node by walking over all uses.

 int ConnectionGraph::add_java_object_edges(JavaObjectNode* jobj, bool populate_worklist) {

   int new_edges = 0;

   if (populate_worklist) {

     // Populate _worklist by uses of jobj's uses.

     for (UseIterator i(jobj); i.has_next(); i.next()) {

       PointsToNode* use = i.get();

       if (use->is_Arraycopy())

         continue;

       add_uses_to_worklist(use);

       if (use->is_Field() && use->as_Field()->is_oop()) {

         // Put on worklist all field's uses (loads) and

         // related field nodes (same base and offset).

         add_field_uses_to_worklist(use->as_Field());

       }

     }

   }

   for (int l = 0; l < _worklist.length(); l++) {

     PointsToNode* use = _worklist.at(l);

     if (PointsToNode::is_base_use(use)) {

       // Add reference from jobj to field and from field to jobj (field's base).

       use = PointsToNode::get_use_node(use)->as_Field();

       if (add_base(use->as_Field(), jobj)) {

         new_edges++;

       }

       continue;

     }

     assert(!use->is_JavaObject(), "sanity");

     if (use->is_Arraycopy()) {

       if (jobj == null_obj) // NULL object does not have field edges

         continue;

       // Added edge from Arraycopy node to arraycopy's source java object

       if (add_edge(use, jobj)) {

         jobj->set_arraycopy_src();

         new_edges++;

       }

       // and stop here.

       continue;

     }

     if (!add_edge(use, jobj))

       continue; // No new edge added, there was such edge already.

     new_edges++;

     if (use->is_LocalVar()) {

       add_uses_to_worklist(use);

       if (use->arraycopy_dst()) {

         for (EdgeIterator i(use); i.has_next(); i.next()) {

           PointsToNode* e = i.get();

           if (e->is_Arraycopy()) {

             if (jobj == null_obj) // NULL object does not have field edges

               continue;

             // Add edge from arraycopy's destination java object to Arraycopy node.

             if (add_edge(jobj, e)) {

               new_edges++;

               jobj->set_arraycopy_dst();

             }

           }

         }

       }

     } else {

       // Added new edge to stored in field values.

       // Put on worklist all field's uses (loads) and

       // related field nodes (same base and offset).

       add_field_uses_to_worklist(use->as_Field());

     }

   }

   _worklist.clear();

   _in_worklist.Reset();

   return new_edges;

 }

 // Put on worklist all related field nodes.

 void ConnectionGraph::add_field_uses_to_worklist(FieldNode* field) {

   assert(field->is_oop(), "sanity");

   int offset = field->offset();

   add_uses_to_worklist(field);

   // Loop over all bases of this field and push on worklist Field nodes

   // with the same offset and base (since they may reference the same field).

   for (BaseIterator i(field); i.has_next(); i.next()) {

     PointsToNode* base = i.get();

     add_fields_to_worklist(field, base);

     // Check if the base was source object of arraycopy and go over arraycopy's

     // destination objects since values stored to a field of source object are

     // accessable by uses (loads) of fields of destination objects.

     if (base->arraycopy_src()) {

       for (UseIterator j(base); j.has_next(); j.next()) {

         PointsToNode* arycp = j.get();

         if (arycp->is_Arraycopy()) {

           for (UseIterator k(arycp); k.has_next(); k.next()) {

             PointsToNode* abase = k.get();

             if (abase->arraycopy_dst() && abase != base) {

               // Look for the same arracopy reference.

               add_fields_to_worklist(field, abase);

             }

           }

         }

       }

     }

   }

 }

 // Put on worklist all related field nodes.

 void ConnectionGraph::add_fields_to_worklist(FieldNode* field, PointsToNode* base) {

   int offset = field->offset();

   if (base->is_LocalVar()) {

     for (UseIterator j(base); j.has_next(); j.next()) {

       PointsToNode* f = j.get();

       if (PointsToNode::is_base_use(f)) { // Field

         f = PointsToNode::get_use_node(f);

         if (f == field || !f->as_Field()->is_oop())

           continue;

         int offs = f->as_Field()->offset();

         if (offs == offset || offset == Type::OffsetBot || offs == Type::OffsetBot) {

           add_to_worklist(f);

         }

       }

     }

   } else {

     assert(base->is_JavaObject(), "sanity");

     if (// Skip phantom_object since it is only used to indicate that

         // this field's content globally escapes.

         (base != phantom_obj) &&

         // NULL object node does not have fields.

         (base != null_obj)) {

       for (EdgeIterator i(base); i.has_next(); i.next()) {

         PointsToNode* f = i.get();

         // Skip arraycopy edge since store to destination object field

         // does not update value in source object field.

         if (f->is_Arraycopy()) {

           assert(base->arraycopy_dst(), "sanity");

           continue;

         }

         if (f == field || !f->as_Field()->is_oop())

           continue;

         int offs = f->as_Field()->offset();

         if (offs == offset || offset == Type::OffsetBot || offs == Type::OffsetBot) {

           add_to_worklist(f);

         }

       }

     }

   }

 }

 // Find fields which have unknown value.

 int ConnectionGraph::find_field_value(FieldNode* field) {

   // Escaped fields should have init value already.

   assert(field->escape_state() == PointsToNode::NoEscape, "sanity");

   int new_edges = 0;

   for (BaseIterator i(field); i.has_next(); i.next()) {

     PointsToNode* base = i.get();

     if (base->is_JavaObject()) {

       // Skip Allocate's fields which will be processed later.

       if (base->ideal_node()->is_Allocate())

         return 0;

       assert(base == null_obj, "only NULL ptr base expected here");

     }

   }

   if (add_edge(field, phantom_obj)) {

     // New edge was added

     new_edges++;

     add_field_uses_to_worklist(field);

   }

   return new_edges;

 }

 // Find fields initializing values for allocations.

 int ConnectionGraph::find_init_values(JavaObjectNode* pta, PointsToNode* init_val, PhaseTransform* phase) {

   assert(pta->escape_state() == PointsToNode::NoEscape, "Not escaped Allocate nodes only");

   int new_edges = 0;

   Node* alloc = pta->ideal_node();

   if (init_val == phantom_obj) {

     // Do nothing for Allocate nodes since its fields values are "known".

     if (alloc->is_Allocate())

       return 0;

     assert(alloc->as_CallStaticJava(), "sanity");

 #ifdef ASSERT

     if (alloc->as_CallStaticJava()->method() == NULL) {

       const char* name = alloc->as_CallStaticJava()->_name;

       assert(strncmp(name, "_multianewarray", 15) == 0, "sanity");

     }

 #endif

     // Non-escaped allocation returned from Java or runtime call have

     // unknown values in fields.

     for (EdgeIterator i(pta); i.has_next(); i.next()) {

       PointsToNode* field = i.get();

       if (field->is_Field() && field->as_Field()->is_oop()) {

         if (add_edge(field, phantom_obj)) {

           // New edge was added

           new_edges++;

           add_field_uses_to_worklist(field->as_Field());

         }

       }

     }

     return new_edges;

   }

   assert(init_val == null_obj, "sanity");

   // Do nothing for Call nodes since its fields values are unknown.

   if (!alloc->is_Allocate())

     return 0;

   InitializeNode* ini = alloc->as_Allocate()->initialization();

   Compile* C = _compile;

   bool visited_bottom_offset = false;

   GrowableArray<int> offsets_worklist;

   // Check if an oop field's initializing value is recorded and add

   // a corresponding NULL if field's value if it is not recorded.

   // Connection Graph does not record a default initialization by NULL

   // captured by Initialize node.

   //

   for (EdgeIterator i(pta); i.has_next(); i.next()) {

     PointsToNode* field = i.get(); // Field (AddP)

     if (!field->is_Field() || !field->as_Field()->is_oop())

       continue; // Not oop field

     int offset = field->as_Field()->offset();

     if (offset == Type::OffsetBot) {

       if (!visited_bottom_offset) {

         // OffsetBot is used to reference array's element,

         // always add reference to NULL to all Field nodes since we don't

         // known which element is referenced.

         if (add_edge(field, null_obj)) {

           // New edge was added

           new_edges++;

           add_field_uses_to_worklist(field->as_Field());

           visited_bottom_offset = true;

         }

       }

     } else {

       // Check only oop fields.

       const Type* adr_type = field->ideal_node()->as_AddP()->bottom_type();

       if (adr_type->isa_rawptr()) {

 #ifdef ASSERT

         // Raw pointers are used for initializing stores so skip it

         // since it should be recorded already

         Node* base = get_addp_base(field->ideal_node());

         assert(adr_type->isa_rawptr() && base->is_Proj() &&

                (base->in(0) == alloc),"unexpected pointer type");

 #endif

         continue;

       }

       if (!offsets_worklist.contains(offset)) {

         offsets_worklist.append(offset);

         Node* value = NULL;

         if (ini != NULL) {

           // StoreP::memory_type() == T_ADDRESS

           BasicType ft = UseCompressedOops ? T_NARROWOOP : T_ADDRESS;

           Node* store = ini->find_captured_store(offset, type2aelembytes(ft, true), phase);

           // Make sure initializing store has the same type as this AddP.

           // This AddP may reference non existing field because it is on a

           // dead branch of bimorphic call which is not eliminated yet.

           if (store != NULL && store->is_Store() &&

               store->as_Store()->memory_type() == ft) {

             value = store->in(MemNode::ValueIn);

 #ifdef ASSERT

             if (VerifyConnectionGraph) {

               // Verify that AddP already points to all objects the value points to.

               PointsToNode* val = ptnode_adr(value->_idx);

               assert((val != NULL), "should be processed already");

               PointsToNode* missed_obj = NULL;

               if (val->is_JavaObject()) {

                 if (!field->points_to(val->as_JavaObject())) {

                   missed_obj = val;

                 }

               } else {

                 if (!val->is_LocalVar() || (val->edge_count() == 0)) {

                   tty->print_cr("----------init store has invalid value -----");

                   store->dump();

                   val->dump();

                   assert(val->is_LocalVar() && (val->edge_count() > 0), "should be processed already");

                 }

                 for (EdgeIterator j(val); j.has_next(); j.next()) {

                   PointsToNode* obj = j.get();

                   if (obj->is_JavaObject()) {

                     if (!field->points_to(obj->as_JavaObject())) {

                       missed_obj = obj;

                       break;

                     }

                   }

                 }

               }

               if (missed_obj != NULL) {

                 tty->print_cr("----------field---------------------------------");

                 field->dump();

                 tty->print_cr("----------missed referernce to object-----------");

                 missed_obj->dump();

                 tty->print_cr("----------object referernced by init store -----");

                 store->dump();

                 val->dump();

                 assert(!field->points_to(missed_obj->as_JavaObject()), "missed JavaObject reference");

               }

             }

 #endif

           } else {

             // There could be initializing stores which follow allocation.

             // For example, a volatile field store is not collected

             // by Initialize node.

             //

             // Need to check for dependent loads to separate such stores from

             // stores which follow loads. For now, add initial value NULL so

             // that compare pointers optimization works correctly.

           }

         }

         if (value == NULL) {

           // A field's initializing value was not recorded. Add NULL.

           if (add_edge(field, null_obj)) {

             // New edge was added

             new_edges++;

             add_field_uses_to_worklist(field->as_Field());

           }

         }

       }

     }

   }

   return new_edges;

 }

 // Adjust scalar_replaceable state after Connection Graph is built.

 void ConnectionGraph::adjust_scalar_replaceable_state(JavaObjectNode* jobj) {

   // Search for non-escaping objects which are not scalar replaceable

   // and mark them to propagate the state to referenced objects.

   // 1. An object is not scalar replaceable if the field into which it is

   // stored has unknown offset (stored into unknown element of an array).

   //

   for (UseIterator i(jobj); i.has_next(); i.next()) {

     PointsToNode* use = i.get();

     assert(!use->is_Arraycopy(), "sanity");

     if (use->is_Field()) {

       FieldNode* field = use->as_Field();

       assert(field->is_oop() && field->scalar_replaceable() &&

              field->fields_escape_state() == PointsToNode::NoEscape, "sanity");

       if (field->offset() == Type::OffsetBot) {

         jobj->set_scalar_replaceable(false);

         return;

       }

       // 2. An object is not scalar replaceable if the field into which it is

       // stored has multiple bases one of which is null.

       if (field->base_count() > 1) {

         for (BaseIterator i(field); i.has_next(); i.next()) {

           PointsToNode* base = i.get();

           if (base == null_obj) {

             jobj->set_scalar_replaceable(false);

             return;

           }

         }

       }

     }

     assert(use->is_Field() || use->is_LocalVar(), "sanity");

     // 3. An object is not scalar replaceable if it is merged with other objects.

     for (EdgeIterator j(use); j.has_next(); j.next()) {

       PointsToNode* ptn = j.get();

       if (ptn->is_JavaObject() && ptn != jobj) {

         // Mark all objects.

         jobj->set_scalar_replaceable(false);

          ptn->set_scalar_replaceable(false);

       }

     }

     if (!jobj->scalar_replaceable()) {

       return;

     }

   }

   for (EdgeIterator j(jobj); j.has_next(); j.next()) {

     // Non-escaping object node should point only to field nodes.

     FieldNode* field = j.get()->as_Field();

     int offset = field->as_Field()->offset();

     // 4. An object is not scalar replaceable if it has a field with unknown

     // offset (array's element is accessed in loop).

     if (offset == Type::OffsetBot) {

       jobj->set_scalar_replaceable(false);

       return;

     }

     // 5. Currently an object is not scalar replaceable if a LoadStore node

     // access its field since the field value is unknown after it.

     //

     Node* n = field->ideal_node();

     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {

       if (n->fast_out(i)->is_LoadStore()) {

         jobj->set_scalar_replaceable(false);

         return;

       }

     }

     // 6. Or the address may point to more then one object. This may produce

     // the false positive result (set not scalar replaceable)

     // since the flow-insensitive escape analysis can't separate

     // the case when stores overwrite the field's value from the case

     // when stores happened on different control branches.

     //

     // Note: it will disable scalar replacement in some cases:

     //

     //    Point p[] = new Point[1];

     //    p[0] = new Point(); // Will be not scalar replaced

     //

     // but it will save us from incorrect optimizations in next cases:

     //

     //    Point p[] = new Point[1];

     //    if ( x ) p[0] = new Point(); // Will be not scalar replaced

     //

     if (field->base_count() > 1) {

       for (BaseIterator i(field); i.has_next(); i.next()) {

         PointsToNode* base = i.get();

         // Don't take into account LocalVar nodes which

         // may point to only one object which should be also

         // this field's base by now.

         if (base->is_JavaObject() && base != jobj) {

           // Mark all bases.

           jobj->set_scalar_replaceable(false);

           base->set_scalar_replaceable(false);

         }

       }

     }

   }

 }

 #ifdef ASSERT

 void ConnectionGraph::verify_connection_graph(

                          GrowableArray<PointsToNode*>&   ptnodes_worklist,

                          GrowableArray<JavaObjectNode*>& non_escaped_worklist,

                          GrowableArray<JavaObjectNode*>& java_objects_worklist,

                          GrowableArray<Node*>& addp_worklist) {

   // Verify that graph is complete - no new edges could be added.

   int java_objects_length = java_objects_worklist.length();

   int non_escaped_length  = non_escaped_worklist.length();

   int new_edges = 0;

   for (int next = 0; next < java_objects_length; ++next) {

     JavaObjectNode* ptn = java_objects_worklist.at(next);

     new_edges += add_java_object_edges(ptn, true);

   }

   assert(new_edges == 0, "graph was not complete");

   // Verify that escape state is final.

   int length = non_escaped_worklist.length();

   find_non_escaped_objects(ptnodes_worklist, non_escaped_worklist);

   assert((non_escaped_length == non_escaped_worklist.length()) &&

          (non_escaped_length == length) &&

          (_worklist.length() == 0), "escape state was not final");

   // Verify fields information.

   int addp_length = addp_worklist.length();

   for (int next = 0; next < addp_length; ++next ) {

     Node* n = addp_worklist.at(next);

     FieldNode* field = ptnode_adr(n->_idx)->as_Field();

     if (field->is_oop()) {

       // Verify that field has all bases

       Node* base = get_addp_base(n);

       PointsToNode* ptn = ptnode_adr(base->_idx);

       if (ptn->is_JavaObject()) {

         assert(field->has_base(ptn->as_JavaObject()), "sanity");

       } else {

         assert(ptn->is_LocalVar(), "sanity");

         for (EdgeIterator i(ptn); i.has_next(); i.next()) {

           PointsToNode* e = i.get();

           if (e->is_JavaObject()) {

             assert(field->has_base(e->as_JavaObject()), "sanity");

           }

         }

       }

       // Verify that all fields have initializing values.

       if (field->edge_count() == 0) {

         tty->print_cr("----------field does not have references----------");

         field->dump();

         for (BaseIterator i(field); i.has_next(); i.next()) {

           PointsToNode* base = i.get();

           tty->print_cr("----------field has next base---------------------");

           base->dump();

           if (base->is_JavaObject() && (base != phantom_obj) && (base != null_obj)) {

             tty->print_cr("----------base has fields-------------------------");

             for (EdgeIterator j(base); j.has_next(); j.next()) {

               j.get()->dump();

             }

             tty->print_cr("----------base has references---------------------");

             for (UseIterator j(base); j.has_next(); j.next()) {

               j.get()->dump();

             }

           }

         }

         for (UseIterator i(field); i.has_next(); i.next()) {

           i.get()->dump();

         }

         assert(field->edge_count() > 0, "sanity");

       }

     }

   }

 }

 #endif

 // Optimize ideal graph.

 void ConnectionGraph::optimize_ideal_graph(GrowableArray<Node*>& ptr_cmp_worklist,

                                            GrowableArray<Node*>& storestore_worklist) {

   Compile* C = _compile;

   PhaseIterGVN* igvn = _igvn;

   if (EliminateLocks) {

     // Mark locks before changing ideal graph.

     int cnt = C->macro_count();

     for( int i=0; i < cnt; i++ ) {

       Node *n = C->macro_node(i);

       if (n->is_AbstractLock()) { // Lock and Unlock nodes

         AbstractLockNode* alock = n->as_AbstractLock();

         if (!alock->is_non_esc_obj()) {

           if (not_global_escape(alock->obj_node())) {

             assert(!alock->is_eliminated() || alock->is_coarsened(), "sanity");

             // The lock could be marked eliminated by lock coarsening

             // code during first IGVN before EA. Replace coarsened flag

             // to eliminate all associated locks/unlocks.

 #ifdef ASSERT

             alock->log_lock_optimization(C, "eliminate_lock_set_non_esc3");

 #endif

             alock->set_non_esc_obj();

           }

         }

       }

     }

   }

   if (OptimizePtrCompare) {

     // Add ConI(#CC_GT) and ConI(#CC_EQ).

     _pcmp_neq = igvn->makecon(TypeInt::CC_GT);

     _pcmp_eq = igvn->makecon(TypeInt::CC_EQ);

     // Optimize objects compare.

     while (ptr_cmp_worklist.length() != 0) {

       Node *n = ptr_cmp_worklist.pop();

       Node *res = optimize_ptr_compare(n);

       if (res != NULL) {

 #ifndef PRODUCT

         if (PrintOptimizePtrCompare) {

           tty->print_cr("++++ Replaced: %d %s(%d,%d) --> %s", n->_idx, (n->Opcode() == Op_CmpP ? "CmpP" : "CmpN"), n->in(1)->_idx, n->in(2)->_idx, (res == _pcmp_eq ? "EQ" : "NotEQ"));

           if (Verbose) {

             n->dump(1);

           }

         }

 #endif

         igvn->replace_node(n, res);

       }

     }

     // cleanup

     if (_pcmp_neq->outcnt() == 0)

       igvn->hash_delete(_pcmp_neq);

     if (_pcmp_eq->outcnt()  == 0)

       igvn->hash_delete(_pcmp_eq);

   }

   // For MemBarStoreStore nodes added in library_call.cpp, check

   // escape status of associated AllocateNode and optimize out

   // MemBarStoreStore node if the allocated object never escapes.

   while (storestore_worklist.length() != 0) {

     Node *n = storestore_worklist.pop();

     MemBarStoreStoreNode *storestore = n ->as_MemBarStoreStore();

     Node *alloc = storestore->in(MemBarNode::Precedent)->in(0);

     assert (alloc->is_Allocate(), "storestore should point to AllocateNode");

     if (not_global_escape(alloc)) {

       MemBarNode* mb = MemBarNode::make(C, Op_MemBarCPUOrder, Compile::AliasIdxBot);

       mb->init_req(TypeFunc::Memory, storestore->in(TypeFunc::Memory));

       mb->init_req(TypeFunc::Control, storestore->in(TypeFunc::Control));

       igvn->register_new_node_with_optimizer(mb);

       igvn->replace_node(storestore, mb);

     }

   }

 }

 // Optimize objects compare.

 Node* ConnectionGraph::optimize_ptr_compare(Node* n) {

   assert(OptimizePtrCompare, "sanity");

   PointsToNode* ptn1 = ptnode_adr(n->in(1)->_idx);

   PointsToNode* ptn2 = ptnode_adr(n->in(2)->_idx);

   JavaObjectNode* jobj1 = unique_java_object(n->in(1));

   JavaObjectNode* jobj2 = unique_java_object(n->in(2));

   assert(ptn1->is_JavaObject() || ptn1->is_LocalVar(), "sanity");

   assert(ptn2->is_JavaObject() || ptn2->is_LocalVar(), "sanity");

   // Check simple cases first.

   if (jobj1 != NULL) {

     if (jobj1->escape_state() == PointsToNode::NoEscape) {

       if (jobj1 == jobj2) {

         // Comparing the same not escaping object.

         return _pcmp_eq;

       }

       Node* obj = jobj1->ideal_node();

       // Comparing not escaping allocation.

       if ((obj->is_Allocate() || obj->is_CallStaticJava()) &&

           !ptn2->points_to(jobj1)) {

         return _pcmp_neq; // This includes nullness check.

       }

     }

   }

   if (jobj2 != NULL) {

     if (jobj2->escape_state() == PointsToNode::NoEscape) {

       Node* obj = jobj2->ideal_node();

       // Comparing not escaping allocation.

       if ((obj->is_Allocate() || obj->is_CallStaticJava()) &&

           !ptn1->points_to(jobj2)) {

         return _pcmp_neq; // This includes nullness check.

       }

     }

   }

   if (jobj1 != NULL && jobj1 != phantom_obj &&

       jobj2 != NULL && jobj2 != phantom_obj &&

       jobj1->ideal_node()->is_Con() &&

       jobj2->ideal_node()->is_Con()) {

     // Klass or String constants compare. Need to be careful with

     // compressed pointers - compare types of ConN and ConP instead of nodes.

     const Type* t1 = jobj1->ideal_node()->get_ptr_type();

     const Type* t2 = jobj2->ideal_node()->get_ptr_type();

     if (t1->make_ptr() == t2->make_ptr()) {

       return _pcmp_eq;

     } else {

       return _pcmp_neq;

     }

   }

   if (ptn1->meet(ptn2)) {

     return NULL; // Sets are not disjoint

   }

   // Sets are disjoint.

   bool set1_has_unknown_ptr = ptn1->points_to(phantom_obj);

   bool set2_has_unknown_ptr = ptn2->points_to(phantom_obj);

   bool set1_has_null_ptr    = ptn1->points_to(null_obj);

   bool set2_has_null_ptr    = ptn2->points_to(null_obj);

   if (set1_has_unknown_ptr && set2_has_null_ptr ||

       set2_has_unknown_ptr && set1_has_null_ptr) {

     // Check nullness of unknown object.

     return NULL;

   }

   // Disjointness by itself is not sufficient since

   // alias analysis is not complete for escaped objects.

   // Disjoint sets are definitely unrelated only when

   // at least one set has only not escaping allocations.

   if (!set1_has_unknown_ptr && !set1_has_null_ptr) {

     if (ptn1->non_escaping_allocation()) {

       return _pcmp_neq;

     }

   }

   if (!set2_has_unknown_ptr && !set2_has_null_ptr) {

     if (ptn2->non_escaping_allocation()) {

       return _pcmp_neq;

     }

   }

   return NULL;

 }

 // Connection Graph constuction functions.

 void ConnectionGraph::add_local_var(Node *n, PointsToNode::EscapeState es) {

   PointsToNode* ptadr = _nodes.at(n->_idx);

   if (ptadr != NULL) {

     assert(ptadr->is_LocalVar() && ptadr->ideal_node() == n, "sanity");

     return;

   }

   Compile* C = _compile;

   ptadr = new (C->comp_arena()) LocalVarNode(this, n, es);

   _nodes.at_put(n->_idx, ptadr);

 }

 void ConnectionGraph::add_java_object(Node *n, PointsToNode::EscapeState es) {

   PointsToNode* ptadr = _nodes.at(n->_idx);

   if (ptadr != NULL) {

     assert(ptadr->is_JavaObject() && ptadr->ideal_node() == n, "sanity");

     return;

   }

   Compile* C = _compile;

   ptadr = new (C->comp_arena()) JavaObjectNode(this, n, es);

   _nodes.at_put(n->_idx, ptadr);

 }

 void ConnectionGraph::add_field(Node *n, PointsToNode::EscapeState es, int offset) {

   PointsToNode* ptadr = _nodes.at(n->_idx);

   if (ptadr != NULL) {

     assert(ptadr->is_Field() && ptadr->ideal_node() == n, "sanity");

     return;

   }

   bool unsafe = false;

   bool is_oop = is_oop_field(n, offset, &unsafe);

   if (unsafe) {

     es = PointsToNode::GlobalEscape;

   }

   Compile* C = _compile;

   FieldNode* field = new (C->comp_arena()) FieldNode(this, n, es, offset, is_oop);

   _nodes.at_put(n->_idx, field);

 }

 void ConnectionGraph::add_arraycopy(Node *n, PointsToNode::EscapeState es,

                                     PointsToNode* src, PointsToNode* dst) {

   assert(!src->is_Field() && !dst->is_Field(), "only for JavaObject and LocalVar");

   assert((src != null_obj) && (dst != null_obj), "not for ConP NULL");

   PointsToNode* ptadr = _nodes.at(n->_idx);

   if (ptadr != NULL) {

     assert(ptadr->is_Arraycopy() && ptadr->ideal_node() == n, "sanity");

     return;

   }

   Compile* C = _compile;

   ptadr = new (C->comp_arena()) ArraycopyNode(this, n, es);

   _nodes.at_put(n->_idx, ptadr);

   // Add edge from arraycopy node to source object.

   (void)add_edge(ptadr, src);

   src->set_arraycopy_src();

   // Add edge from destination object to arraycopy node.

   (void)add_edge(dst, ptadr);

   dst->set_arraycopy_dst();

 }

 bool ConnectionGraph::is_oop_field(Node* n, int offset, bool* unsafe) {

   const Type* adr_type = n->as_AddP()->bottom_type();

   BasicType bt = T_INT;

   if (offset == Type::OffsetBot) {

     // Check only oop fields.

     if (!adr_type->isa_aryptr() ||

         (adr_type->isa_aryptr()->klass() == NULL) ||

          adr_type->isa_aryptr()->klass()->is_obj_array_klass()) {

       // OffsetBot is used to reference array's element. Ignore first AddP.

       if (find_second_addp(n, n->in(AddPNode::Base)) == NULL) {

         bt = T_OBJECT;

       }

     }

   } else if (offset != oopDesc::klass_offset_in_bytes()) {

     if (adr_type->isa_instptr()) {

       ciField* field = _compile->alias_type(adr_type->isa_instptr())->field();

       if (field != NULL) {

         bt = field->layout_type();

       } else {

         // Check for unsafe oop field access

         for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {

           int opcode = n->fast_out(i)->Opcode();

           if (opcode == Op_StoreP || opcode == Op_LoadP ||

               opcode == Op_StoreN || opcode == Op_LoadN) {

             bt = T_OBJECT;

             (*unsafe) = true;

             break;

           }

         }

       }

     } else if (adr_type->isa_aryptr()) {

       if (offset == arrayOopDesc::length_offset_in_bytes()) {

         // Ignore array length load.

       } else if (find_second_addp(n, n->in(AddPNode::Base)) != NULL) {

         // Ignore first AddP.

       } else {

         const Type* elemtype = adr_type->isa_aryptr()->elem();

         bt = elemtype->array_element_basic_type();

       }

     } else if (adr_type->isa_rawptr() || adr_type->isa_klassptr()) {

       // Allocation initialization, ThreadLocal field access, unsafe access

       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {

         int opcode = n->fast_out(i)->Opcode();

         if (opcode == Op_StoreP || opcode == Op_LoadP ||

             opcode == Op_StoreN || opcode == Op_LoadN) {

           bt = T_OBJECT;

           break;

         }

       }

     }

   }

   return (bt == T_OBJECT || bt == T_NARROWOOP || bt == T_ARRAY);

 }

 // Returns unique pointed java object or NULL.

 JavaObjectNode* ConnectionGraph::unique_java_object(Node *n) {

   assert(!_collecting, "should not call when contructed graph");

   // If the node was created after the escape computation we can't answer.

   uint idx = n->_idx;

   if (idx >= nodes_size()) {

     return NULL;

   }

   PointsToNode* ptn = ptnode_adr(idx);

   if (ptn->is_JavaObject()) {

     return ptn->as_JavaObject();

   }

   assert(ptn->is_LocalVar(), "sanity");

   // Check all java objects it points to.

   JavaObjectNode* jobj = NULL;

   for (EdgeIterator i(ptn); i.has_next(); i.next()) {

     PointsToNode* e = i.get();

     if (e->is_JavaObject()) {

       if (jobj == NULL) {

         jobj = e->as_JavaObject();

       } else if (jobj != e) {

         return NULL;

       }

     }

   }

   return jobj;

 }

 // Return true if this node points only to non-escaping allocations.

 bool PointsToNode::non_escaping_allocation() {

   if (is_JavaObject()) {

     Node* n = ideal_node();

     if (n->is_Allocate() || n->is_CallStaticJava()) {

       return (escape_state() == PointsToNode::NoEscape);

     } else {

       return false;

     }

   }

   assert(is_LocalVar(), "sanity");

   // Check all java objects it points to.

   for (EdgeIterator i(this); i.has_next(); i.next()) {

     PointsToNode* e = i.get();

     if (e->is_JavaObject()) {

       Node* n = e->ideal_node();

       if ((e->escape_state() != PointsToNode::NoEscape) ||

           !(n->is_Allocate() || n->is_CallStaticJava())) {

         return false;

       }

     }

   }

   return true;

 }

 // Return true if we know the node does not escape globally.

 bool ConnectionGraph::not_global_escape(Node *n) {

   assert(!_collecting, "should not call during graph construction");

   // If the node was created after the escape computation we can't answer.

   uint idx = n->_idx;

   if (idx >= nodes_size()) {

     return false;

   }

   PointsToNode* ptn = ptnode_adr(idx);

   PointsToNode::EscapeState es = ptn->escape_state();

   // If we have already computed a value, return it.

   if (es >= PointsToNode::GlobalEscape)

     return false;

   if (ptn->is_JavaObject()) {

     return true; // (es < PointsToNode::GlobalEscape);

   }

   assert(ptn->is_LocalVar(), "sanity");

   // Check all java objects it points to.

   for (EdgeIterator i(ptn); i.has_next(); i.next()) {

     if (i.get()->escape_state() >= PointsToNode::GlobalEscape)

       return false;

   }

   return true;

 }

 // Helper functions

 // Return true if this node points to specified node or nodes it points to.

 bool PointsToNode::points_to(JavaObjectNode* ptn) const {

   if (is_JavaObject()) {

     return (this == ptn);

   }

   assert(is_LocalVar() || is_Field(), "sanity");

   for (EdgeIterator i(this); i.has_next(); i.next()) {

     if (i.get() == ptn)

       return true;

   }

   return false;

 }

 // Return true if one node points to an other.

 bool PointsToNode::meet(PointsToNode* ptn) {

   if (this == ptn) {

     return true;

   } else if (ptn->is_JavaObject()) {

     return this->points_to(ptn->as_JavaObject());

   } else if (this->is_JavaObject()) {

     return ptn->points_to(this->as_JavaObject());

   }

   assert(this->is_LocalVar() && ptn->is_LocalVar(), "sanity");

   int ptn_count =  ptn->edge_count();

   for (EdgeIterator i(this); i.has_next(); i.next()) {

     PointsToNode* this_e = i.get();

     for (int j = 0; j < ptn_count; j++) {

       if (this_e == ptn->edge(j))

         return true;

     }

   }

   return false;

 }

 #ifdef ASSERT

 // Return true if bases point to this java object.

 bool FieldNode::has_base(JavaObjectNode* jobj) const {

   for (BaseIterator i(this); i.has_next(); i.next()) {

     if (i.get() == jobj)

       return true;

   }

   return false;

 }

 #endif

 int ConnectionGraph::address_offset(Node* adr, PhaseTransform *phase) {

   const Type *adr_type = phase->type(adr);

   if (adr->is_AddP() && adr_type->isa_oopptr() == NULL &&

       adr->in(AddPNode::Address)->is_Proj() &&

       adr->in(AddPNode::Address)->in(0)->is_Allocate()) {

     // We are computing a raw address for a store captured by an Initialize

     // compute an appropriate address type. AddP cases #3 and #5 (see below).

     int offs = (int)phase->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);

     assert(offs != Type::OffsetBot ||

            adr->in(AddPNode::Address)->in(0)->is_AllocateArray(),

            "offset must be a constant or it is initialization of array");

     return offs;

   }

   const TypePtr *t_ptr = adr_type->isa_ptr();

   assert(t_ptr != NULL, "must be a pointer type");

   return t_ptr->offset();

 }

 Node* ConnectionGraph::get_addp_base(Node *addp) {

   assert(addp->is_AddP(), "must be AddP");

   //

   // AddP cases for Base and Address inputs:

   // case #1. Direct object's field reference:

   //     Allocate

   //       |

   //     Proj #5 ( oop result )

   //       |

   //     CheckCastPP (cast to instance type)

   //      | |

   //     AddP  ( base == address )

   //

   // case #2. Indirect object's field reference:

   //      Phi

   //       |

   //     CastPP (cast to instance type)

   //      | |

   //     AddP  ( base == address )

   //

   // case #3. Raw object's field reference for Initialize node:

   //      Allocate

   //        |

   //      Proj #5 ( oop result )

   //  top   |

   //     \  |

   //     AddP  ( base == top )

   //

   // case #4. Array's element reference:

   //   {CheckCastPP | CastPP}

   //     |  | |

   //     |  AddP ( array's element offset )

   //     |  |

   //     AddP ( array's offset )

   //

   // case #5. Raw object's field reference for arraycopy stub call:

   //          The inline_native_clone() case when the arraycopy stub is called

   //          after the allocation before Initialize and CheckCastPP nodes.

   //      Allocate

   //        |

   //      Proj #5 ( oop result )

   //       | |

   //       AddP  ( base == address )

   //

   // case #6. Constant Pool, ThreadLocal, CastX2P or

   //          Raw object's field reference:

   //      {ConP, ThreadLocal, CastX2P, raw Load}

   //  top   |

   //     \  |

   //     AddP  ( base == top )

   //

   // case #7. Klass's field reference.

   //      LoadKlass

   //       | |

   //       AddP  ( base == address )

   //

   // case #8. narrow Klass's field reference.

   //      LoadNKlass

   //       |

   //      DecodeN

   //       | |

   //       AddP  ( base == address )

   //

   Node *base = addp->in(AddPNode::Base);

   if (base->uncast()->is_top()) { // The AddP case #3 and #6.

     base = addp->in(AddPNode::Address);

     while (base->is_AddP()) {

       // Case #6 (unsafe access) may have several chained AddP nodes.

       assert(base->in(AddPNode::Base)->uncast()->is_top(), "expected unsafe access address only");

       base = base->in(AddPNode::Address);

     }

     Node* uncast_base = base->uncast();

     int opcode = uncast_base->Opcode();

     assert(opcode == Op_ConP || opcode == Op_ThreadLocal ||

            opcode == Op_CastX2P || uncast_base->is_DecodeNarrowPtr() ||

            (uncast_base->is_Mem() && (uncast_base->bottom_type()->isa_rawptr() != NULL)) ||

            (uncast_base->is_Proj() && uncast_base->in(0)->is_Allocate()), "sanity");

   }

   return base;

 }

 Node* ConnectionGraph::find_second_addp(Node* addp, Node* n) {

   assert(addp->is_AddP() && addp->outcnt() > 0, "Don't process dead nodes");

   Node* addp2 = addp->raw_out(0);

   if (addp->outcnt() == 1 && addp2->is_AddP() &&

       addp2->in(AddPNode::Base) == n &&

       addp2->in(AddPNode::Address) == addp) {

     assert(addp->in(AddPNode::Base) == n, "expecting the same base");

     //

     // Find array's offset to push it on worklist first and

     // as result process an array's element offset first (pushed second)

     // to avoid CastPP for the array's offset.

     // Otherwise the inserted CastPP (LocalVar) will point to what

     // the AddP (Field) points to. Which would be wrong since

     // the algorithm expects the CastPP has the same point as

     // as AddP's base CheckCastPP (LocalVar).

     //

     //    ArrayAllocation

     //     |

     //    CheckCastPP

     //     |

     //    memProj (from ArrayAllocation CheckCastPP)

     //     |  ||

     //     |  ||   Int (element index)

     //     |  ||    |   ConI (log(element size))

     //     |  ||    |   /

     //     |  ||   LShift

     //     |  ||  /

     //     |  AddP (array's element offset)

     //     |  |

     //     |  | ConI (array's offset: #12(32-bits) or #24(64-bits))

     //     | / /

     //     AddP (array's offset)

     //      |

     //     Load/Store (memory operation on array's element)

     //

     return addp2;

   }

   return NULL;

 }

 //

 // Adjust the type and inputs of an AddP which computes the

 // address of a field of an instance

 //

 bool ConnectionGraph::split_AddP(Node *addp, Node *base) {

   PhaseGVN* igvn = _igvn;

   const TypeOopPtr *base_t = igvn->type(base)->isa_oopptr();

   assert(base_t != NULL && base_t->is_known_instance(), "expecting instance oopptr");

   const TypeOopPtr *t = igvn->type(addp)->isa_oopptr();

   if (t == NULL) {

     // We are computing a raw address for a store captured by an Initialize

     // compute an appropriate address type (cases #3 and #5).

     assert(igvn->type(addp) == TypeRawPtr::NOTNULL, "must be raw pointer");

     assert(addp->in(AddPNode::Address)->is_Proj(), "base of raw address must be result projection from allocation");

     intptr_t offs = (int)igvn->find_intptr_t_con(addp->in(AddPNode::Offset), Type::OffsetBot);

     assert(offs != Type::OffsetBot, "offset must be a constant");

     t = base_t->add_offset(offs)->is_oopptr();

   }

   int inst_id =  base_t->instance_id();

   assert(!t->is_known_instance() || t->instance_id() == inst_id,

                              "old type must be non-instance or match new type");

   // The type 't' could be subclass of 'base_t'.

   // As result t->offset() could be large then base_t's size and it will

   // cause the failure in add_offset() with narrow oops since TypeOopPtr()

   // constructor verifies correctness of the offset.

   //

   // It could happened on subclass's branch (from the type profiling

   // inlining) which was not eliminated during parsing since the exactness

   // of the allocation type was not propagated to the subclass type check.

   //

   // Or the type 't' could be not related to 'base_t' at all.

   // It could happened when CHA type is different from MDO type on a dead path

   // (for example, from instanceof check) which is not collapsed during parsing.

   //

   // Do nothing for such AddP node and don't process its users since

   // this code branch will go away.

   //

   if (!t->is_known_instance() &&

       !base_t->klass()->is_subtype_of(t->klass())) {

      return false; // bail out

   }

   const TypeOopPtr *tinst = base_t->add_offset(t->offset())->is_oopptr();

   // Do NOT remove the next line: ensure a new alias index is allocated

   // for the instance type. Note: C++ will not remove it since the call

   // has side effect.

   int alias_idx = _compile->get_alias_index(tinst);

   igvn->set_type(addp, tinst);

   // record the allocation in the node map

   set_map(addp, get_map(base->_idx));

   // Set addp's Base and Address to 'base'.

   Node *abase = addp->in(AddPNode::Base);

   Node *adr   = addp->in(AddPNode::Address);

   if (adr->is_Proj() && adr->in(0)->is_Allocate() &&

       adr->in(0)->_idx == (uint)inst_id) {

     // Skip AddP cases #3 and #5.

   } else {

     assert(!abase->is_top(), "sanity"); // AddP case #3

     if (abase != base) {

       igvn->hash_delete(addp);

       addp->set_req(AddPNode::Base, base);

       if (abase == adr) {

         addp->set_req(AddPNode::Address, base);

       } else {

         // AddP case #4 (adr is array's element offset AddP node)

 #ifdef ASSERT

         const TypeOopPtr *atype = igvn->type(adr)->isa_oopptr();

         assert(adr->is_AddP() && atype != NULL &&

                atype->instance_id() == inst_id, "array's element offset should be processed first");

 #endif

       }

       igvn->hash_insert(addp);

     }

   }

   // Put on IGVN worklist since at least addp's type was changed above.

   record_for_optimizer(addp);

   return true;

 }

 //

 // Create a new version of orig_phi if necessary. Returns either the newly

 // created phi or an existing phi.  Sets create_new to indicate whether a new

 // phi was created.  Cache the last newly created phi in the node map.

 //

 PhiNode *ConnectionGraph::create_split_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist, bool &new_created) {

   Compile *C = _compile;

   PhaseGVN* igvn = _igvn;

   new_created = false;

   int phi_alias_idx = C->get_alias_index(orig_phi->adr_type());

   // nothing to do if orig_phi is bottom memory or matches alias_idx

   if (phi_alias_idx == alias_idx) {

     return orig_phi;

   }

   // Have we recently created a Phi for this alias index?

   PhiNode *result = get_map_phi(orig_phi->_idx);

   if (result != NULL && C->get_alias_index(result->adr_type()) == alias_idx) {

     return result;

   }

   // Previous check may fail when the same wide memory Phi was split into Phis

   // for different memory slices. Search all Phis for this region.

   if (result != NULL) {

     Node* region = orig_phi->in(0);

     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {

       Node* phi = region->fast_out(i);

       if (phi->is_Phi() &&

           C->get_alias_index(phi->as_Phi()->adr_type()) == alias_idx) {

         assert(phi->_idx >= nodes_size(), "only new Phi per instance memory slice");

         return phi->as_Phi();

       }

     }

   }

   if (C->live_nodes() + 2*NodeLimitFudgeFactor > C->max_node_limit()) {

     if (C->do_escape_analysis() == true && !C->failing()) {

       // Retry compilation without escape analysis.

       // If this is the first failure, the sentinel string will "stick"

       // to the Compile object, and the C2Compiler will see it and retry.

       C->record_failure(C2Compiler::retry_no_escape_analysis());

     }

     return NULL;

   }

   orig_phi_worklist.append_if_missing(orig_phi);

   const TypePtr *atype = C->get_adr_type(alias_idx);

   result = PhiNode::make(orig_phi->in(0), NULL, Type::MEMORY, atype);

   C->copy_node_notes_to(result, orig_phi);

   igvn->set_type(result, result->bottom_type());

   record_for_optimizer(result);

   set_map(orig_phi, result);

   new_created = true;

   return result;

 }

 //

 // Return a new version of Memory Phi "orig_phi" with the inputs having the

 // specified alias index.

 //

 PhiNode *ConnectionGraph::split_memory_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist) {

   assert(alias_idx != Compile::AliasIdxBot, "can't split out bottom memory");

   Compile *C = _compile;

   PhaseGVN* igvn = _igvn;

   bool new_phi_created;

   PhiNode *result = create_split_phi(orig_phi, alias_idx, orig_phi_worklist, new_phi_created);

   if (!new_phi_created) {

     return result;

   }

   GrowableArray<PhiNode *>  phi_list;

   GrowableArray<uint>  cur_input;

   PhiNode *phi = orig_phi;

   uint idx = 1;

   bool finished = false;

   while(!finished) {

     while (idx < phi->req()) {

       Node *mem = find_inst_mem(phi->in(idx), alias_idx, orig_phi_worklist);

       if (mem != NULL && mem->is_Phi()) {

         PhiNode *newphi = create_split_phi(mem->as_Phi(), alias_idx, orig_phi_worklist, new_phi_created);

         if (new_phi_created) {

           // found an phi for which we created a new split, push current one on worklist and begin

           // processing new one

           phi_list.push(phi);

           cur_input.push(idx);

           phi = mem->as_Phi();

           result = newphi;

           idx = 1;

           continue;

         } else {

           mem = newphi;

         }

       }

       if (C->failing()) {

         return NULL;

       }

       result->set_req(idx++, mem);

     }

 #ifdef ASSERT

     // verify that the new Phi has an input for each input of the original

     assert( phi->req() == result->req(), "must have same number of inputs.");

     assert( result->in(0) != NULL && result->in(0) == phi->in(0), "regions must match");

 #endif

     // Check if all new phi's inputs have specified alias index.

     // Otherwise use old phi.

     for (uint i = 1; i < phi->req(); i++) {

       Node* in = result->in(i);

       assert((phi->in(i) == NULL) == (in == NULL), "inputs must correspond.");

     }

     // we have finished processing a Phi, see if there are any more to do

     finished = (phi_list.length() == 0 );

     if (!finished) {

       phi = phi_list.pop();

       idx = cur_input.pop();

       PhiNode *prev_result = get_map_phi(phi->_idx);

       prev_result->set_req(idx++, result);

       result = prev_result;

     }

   }

   return result;

 }

 //

 // The next methods are derived from methods in MemNode.

 //

 Node* ConnectionGraph::step_through_mergemem(MergeMemNode *mmem, int alias_idx, const TypeOopPtr *toop) {

   Node *mem = mmem;

   // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally

   // means an array I have not precisely typed yet.  Do not do any

   // alias stuff with it any time soon.

   if (toop->base() != Type::AnyPtr &&

       !(toop->klass() != NULL &&

         toop->klass()->is_java_lang_Object() &&

         toop->offset() == Type::OffsetBot)) {

     mem = mmem->memory_at(alias_idx);

     // Update input if it is progress over what we have now

   }

   return mem;

 }

 //

 // Move memory users to their memory slices.

 //

 void ConnectionGraph::move_inst_mem(Node* n, GrowableArray<PhiNode *>  &orig_phis) {

   Compile* C = _compile;

   PhaseGVN* igvn = _igvn;

   const TypePtr* tp = igvn->type(n->in(MemNode::Address))->isa_ptr();

   assert(tp != NULL, "ptr type");

   int alias_idx = C->get_alias_index(tp);

   int general_idx = C->get_general_index(alias_idx);

   // Move users first

   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {

     Node* use = n->fast_out(i);

     if (use->is_MergeMem()) {

       MergeMemNode* mmem = use->as_MergeMem();

       assert(n == mmem->memory_at(alias_idx), "should be on instance memory slice");

       if (n != mmem->memory_at(general_idx) || alias_idx == general_idx) {

         continue; // Nothing to do

       }

       // Replace previous general reference to mem node.

       uint orig_uniq = C->unique();

       Node* m = find_inst_mem(n, general_idx, orig_phis);

       assert(orig_uniq == C->unique(), "no new nodes");

       mmem->set_memory_at(general_idx, m);

       --imax;

       --i;

     } else if (use->is_MemBar()) {

       assert(!use->is_Initialize(), "initializing stores should not be moved");

       if (use->req() > MemBarNode::Precedent &&

           use->in(MemBarNode::Precedent) == n) {

         // Don't move related membars.

         record_for_optimizer(use);

         continue;

       }

       tp = use->as_MemBar()->adr_type()->isa_ptr();

       if (tp != NULL && C->get_alias_index(tp) == alias_idx ||

           alias_idx == general_idx) {

         continue; // Nothing to do

       }

       // Move to general memory slice.

       uint orig_uniq = C->unique();

       Node* m = find_inst_mem(n, general_idx, orig_phis);

       assert(orig_uniq == C->unique(), "no new nodes");

       igvn->hash_delete(use);

       imax -= use->replace_edge(n, m);

       igvn->hash_insert(use);

       record_for_optimizer(use);

       --i;

 #ifdef ASSERT

     } else if (use->is_Mem()) {

       if (use->Opcode() == Op_StoreCM && use->in(MemNode::OopStore) == n) {

         // Don't move related cardmark.

         continue;

       }

       // Memory nodes should have new memory input.

       tp = igvn->type(use->in(MemNode::Address))->isa_ptr();

       assert(tp != NULL, "ptr type");

       int idx = C->get_alias_index(tp);

       assert(get_map(use->_idx) != NULL || idx == alias_idx,

              "Following memory nodes should have new memory input or be on the same memory slice");

     } else if (use->is_Phi()) {

       // Phi nodes should be split and moved already.

       tp = use->as_Phi()->adr_type()->isa_ptr();

       assert(tp != NULL, "ptr type");

       int idx = C->get_alias_index(tp);

       assert(idx == alias_idx, "Following Phi nodes should be on the same memory slice");

     } else {

       use->dump();

       assert(false, "should not be here");

 #endif

     }

   }

 }

 //

 // Search memory chain of "mem" to find a MemNode whose address

 // is the specified alias index.

 //

 Node* ConnectionGraph::find_inst_mem(Node *orig_mem, int alias_idx, GrowableArray<PhiNode *>  &orig_phis) {

   if (orig_mem == NULL)

     return orig_mem;

   Compile* C = _compile;

   PhaseGVN* igvn = _igvn;

   const TypeOopPtr *toop = C->get_adr_type(alias_idx)->isa_oopptr();

   bool is_instance = (toop != NULL) && toop->is_known_instance();

   Node *start_mem = C->start()->proj_out(TypeFunc::Memory);

   Node *prev = NULL;

   Node *result = orig_mem;

   while (prev != result) {

     prev = result;

     if (result == start_mem)

       break;  // hit one of our sentinels

     if (result->is_Mem()) {

       const Type *at = igvn->type(result->in(MemNode::Address));

       if (at == Type::TOP)

         break; // Dead

       assert (at->isa_ptr() != NULL, "pointer type required.");

       int idx = C->get_alias_index(at->is_ptr());

       if (idx == alias_idx)

         break; // Found

       if (!is_instance && (at->isa_oopptr() == NULL ||

                            !at->is_oopptr()->is_known_instance())) {

         break; // Do not skip store to general memory slice.

       }

       result = result->in(MemNode::Memory);

     }

     if (!is_instance)

       continue;  // don't search further for non-instance types

     // skip over a call which does not affect this memory slice

     if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {

       Node *proj_in = result->in(0);

       if (proj_in->is_Allocate() && proj_in->_idx == (uint)toop->instance_id()) {

         break;  // hit one of our sentinels

       } else if (proj_in->is_Call()) {