1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/barrierSet.hpp"
  27 #include "gc/shared/c2/barrierSetC2.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "memory/resourceArea.hpp"
  30 #include "opto/block.hpp"
  31 #include "opto/callnode.hpp"
  32 #include "opto/castnode.hpp"
  33 #include "opto/cfgnode.hpp"
  34 #include "opto/idealGraphPrinter.hpp"
  35 #include "opto/loopnode.hpp"
  36 #include "opto/machnode.hpp"
  37 #include "opto/opcodes.hpp"
  38 #include "opto/phaseX.hpp"
  39 #include "opto/regalloc.hpp"
  40 #include "opto/rootnode.hpp"
  41 #include "utilities/macros.hpp"
  42 
  43 //=============================================================================
  44 #define NODE_HASH_MINIMUM_SIZE    255
  45 //------------------------------NodeHash---------------------------------------
  46 NodeHash::NodeHash(uint est_max_size) :
  47   _a(Thread::current()->resource_area()),
  48   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
  49   _inserts(0), _insert_limit( insert_limit() ),
  50   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) ) // (Node**)_a->Amalloc(_max * sizeof(Node*)) ),
  51 #ifndef PRODUCT
  52   , _grows(0),_look_probes(0), _lookup_hits(0), _lookup_misses(0),
  53   _insert_probes(0), _delete_probes(0), _delete_hits(0), _delete_misses(0),
  54    _total_inserts(0), _total_insert_probes(0)
  55 #endif
  56 {
  57   // _sentinel must be in the current node space
  58   _sentinel = new ProjNode(NULL, TypeFunc::Control);
  59   memset(_table,0,sizeof(Node*)*_max);
  60 }
  61 
  62 //------------------------------NodeHash---------------------------------------
  63 NodeHash::NodeHash(Arena *arena, uint est_max_size) :
  64   _a(arena),
  65   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
  66   _inserts(0), _insert_limit( insert_limit() ),
  67   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) )
  68 #ifndef PRODUCT
  69   , _grows(0),_look_probes(0), _lookup_hits(0), _lookup_misses(0),
  70   _insert_probes(0), _delete_probes(0), _delete_hits(0), _delete_misses(0),
  71    _total_inserts(0), _total_insert_probes(0)
  72 #endif
  73 {
  74   // _sentinel must be in the current node space
  75   _sentinel = new ProjNode(NULL, TypeFunc::Control);
  76   memset(_table,0,sizeof(Node*)*_max);
  77 }
  78 
  79 //------------------------------NodeHash---------------------------------------
  80 NodeHash::NodeHash(NodeHash *nh) {
  81   debug_only(_table = (Node**)badAddress);   // interact correctly w/ operator=
  82   // just copy in all the fields
  83   *this = *nh;
  84   // nh->_sentinel must be in the current node space
  85 }
  86 
  87 void NodeHash::replace_with(NodeHash *nh) {
  88   debug_only(_table = (Node**)badAddress);   // interact correctly w/ operator=
  89   // just copy in all the fields
  90   *this = *nh;
  91   // nh->_sentinel must be in the current node space
  92 }
  93 
  94 //------------------------------hash_find--------------------------------------
  95 // Find in hash table
  96 Node *NodeHash::hash_find( const Node *n ) {
  97   // ((Node*)n)->set_hash( n->hash() );
  98   uint hash = n->hash();
  99   if (hash == Node::NO_HASH) {
 100     NOT_PRODUCT( _lookup_misses++ );
 101     return NULL;
 102   }
 103   uint key = hash & (_max-1);
 104   uint stride = key | 0x01;
 105   NOT_PRODUCT( _look_probes++ );
 106   Node *k = _table[key];        // Get hashed value
 107   if( !k ) {                    // ?Miss?
 108     NOT_PRODUCT( _lookup_misses++ );
 109     return NULL;                // Miss!
 110   }
 111 
 112   int op = n->Opcode();
 113   uint req = n->req();
 114   while( 1 ) {                  // While probing hash table
 115     if( k->req() == req &&      // Same count of inputs
 116         k->Opcode() == op ) {   // Same Opcode
 117       for( uint i=0; i<req; i++ )
 118         if( n->in(i)!=k->in(i)) // Different inputs?
 119           goto collision;       // "goto" is a speed hack...
 120       if( n->cmp(*k) ) {        // Check for any special bits
 121         NOT_PRODUCT( _lookup_hits++ );
 122         return k;               // Hit!
 123       }
 124     }
 125   collision:
 126     NOT_PRODUCT( _look_probes++ );
 127     key = (key + stride/*7*/) & (_max-1); // Stride through table with relative prime
 128     k = _table[key];            // Get hashed value
 129     if( !k ) {                  // ?Miss?
 130       NOT_PRODUCT( _lookup_misses++ );
 131       return NULL;              // Miss!
 132     }
 133   }
 134   ShouldNotReachHere();
 135   return NULL;
 136 }
 137 
 138 //------------------------------hash_find_insert-------------------------------
 139 // Find in hash table, insert if not already present
 140 // Used to preserve unique entries in hash table
 141 Node *NodeHash::hash_find_insert( Node *n ) {
 142   // n->set_hash( );
 143   uint hash = n->hash();
 144   if (hash == Node::NO_HASH) {
 145     NOT_PRODUCT( _lookup_misses++ );
 146     return NULL;
 147   }
 148   uint key = hash & (_max-1);
 149   uint stride = key | 0x01;     // stride must be relatively prime to table siz
 150   uint first_sentinel = 0;      // replace a sentinel if seen.
 151   NOT_PRODUCT( _look_probes++ );
 152   Node *k = _table[key];        // Get hashed value
 153   if( !k ) {                    // ?Miss?
 154     NOT_PRODUCT( _lookup_misses++ );
 155     _table[key] = n;            // Insert into table!
 156     debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 157     check_grow();               // Grow table if insert hit limit
 158     return NULL;                // Miss!
 159   }
 160   else if( k == _sentinel ) {
 161     first_sentinel = key;      // Can insert here
 162   }
 163 
 164   int op = n->Opcode();
 165   uint req = n->req();
 166   while( 1 ) {                  // While probing hash table
 167     if( k->req() == req &&      // Same count of inputs
 168         k->Opcode() == op ) {   // Same Opcode
 169       for( uint i=0; i<req; i++ )
 170         if( n->in(i)!=k->in(i)) // Different inputs?
 171           goto collision;       // "goto" is a speed hack...
 172       if( n->cmp(*k) ) {        // Check for any special bits
 173         NOT_PRODUCT( _lookup_hits++ );
 174         return k;               // Hit!
 175       }
 176     }
 177   collision:
 178     NOT_PRODUCT( _look_probes++ );
 179     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
 180     k = _table[key];            // Get hashed value
 181     if( !k ) {                  // ?Miss?
 182       NOT_PRODUCT( _lookup_misses++ );
 183       key = (first_sentinel == 0) ? key : first_sentinel; // ?saw sentinel?
 184       _table[key] = n;          // Insert into table!
 185       debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 186       check_grow();             // Grow table if insert hit limit
 187       return NULL;              // Miss!
 188     }
 189     else if( first_sentinel == 0 && k == _sentinel ) {
 190       first_sentinel = key;    // Can insert here
 191     }
 192 
 193   }
 194   ShouldNotReachHere();
 195   return NULL;
 196 }
 197 
 198 //------------------------------hash_insert------------------------------------
 199 // Insert into hash table
 200 void NodeHash::hash_insert( Node *n ) {
 201   // // "conflict" comments -- print nodes that conflict
 202   // bool conflict = false;
 203   // n->set_hash();
 204   uint hash = n->hash();
 205   if (hash == Node::NO_HASH) {
 206     return;
 207   }
 208   check_grow();
 209   uint key = hash & (_max-1);
 210   uint stride = key | 0x01;
 211 
 212   while( 1 ) {                  // While probing hash table
 213     NOT_PRODUCT( _insert_probes++ );
 214     Node *k = _table[key];      // Get hashed value
 215     if( !k || (k == _sentinel) ) break;       // Found a slot
 216     assert( k != n, "already inserted" );
 217     // if( PrintCompilation && PrintOptoStatistics && Verbose ) { tty->print("  conflict: "); k->dump(); conflict = true; }
 218     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
 219   }
 220   _table[key] = n;              // Insert into table!
 221   debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 222   // if( conflict ) { n->dump(); }
 223 }
 224 
 225 //------------------------------hash_delete------------------------------------
 226 // Replace in hash table with sentinel
 227 bool NodeHash::hash_delete( const Node *n ) {
 228   Node *k;
 229   uint hash = n->hash();
 230   if (hash == Node::NO_HASH) {
 231     NOT_PRODUCT( _delete_misses++ );
 232     return false;
 233   }
 234   uint key = hash & (_max-1);
 235   uint stride = key | 0x01;
 236   debug_only( uint counter = 0; );
 237   for( ; /* (k != NULL) && (k != _sentinel) */; ) {
 238     debug_only( counter++ );
 239     NOT_PRODUCT( _delete_probes++ );
 240     k = _table[key];            // Get hashed value
 241     if( !k ) {                  // Miss?
 242       NOT_PRODUCT( _delete_misses++ );
 243       return false;             // Miss! Not in chain
 244     }
 245     else if( n == k ) {
 246       NOT_PRODUCT( _delete_hits++ );
 247       _table[key] = _sentinel;  // Hit! Label as deleted entry
 248       debug_only(((Node*)n)->exit_hash_lock()); // Unlock the node upon removal from table.
 249       return true;
 250     }
 251     else {
 252       // collision: move through table with prime offset
 253       key = (key + stride/*7*/) & (_max-1);
 254       assert( counter <= _insert_limit, "Cycle in hash-table");
 255     }
 256   }
 257   ShouldNotReachHere();
 258   return false;
 259 }
 260 
 261 //------------------------------round_up---------------------------------------
 262 // Round up to nearest power of 2
 263 uint NodeHash::round_up( uint x ) {
 264   x += (x>>2);                  // Add 25% slop
 265   if( x <16 ) return 16;        // Small stuff
 266   uint i=16;
 267   while( i < x ) i <<= 1;       // Double to fit
 268   return i;                     // Return hash table size
 269 }
 270 
 271 //------------------------------grow-------------------------------------------
 272 // Grow _table to next power of 2 and insert old entries
 273 void  NodeHash::grow() {
 274   // Record old state
 275   uint   old_max   = _max;
 276   Node **old_table = _table;
 277   // Construct new table with twice the space
 278 #ifndef PRODUCT
 279   _grows++;
 280   _total_inserts       += _inserts;
 281   _total_insert_probes += _insert_probes;
 282   _insert_probes   = 0;
 283 #endif
 284   _inserts         = 0;
 285   _max     = _max << 1;
 286   _table   = NEW_ARENA_ARRAY( _a , Node* , _max ); // (Node**)_a->Amalloc( _max * sizeof(Node*) );
 287   memset(_table,0,sizeof(Node*)*_max);
 288   _insert_limit = insert_limit();
 289   // Insert old entries into the new table
 290   for( uint i = 0; i < old_max; i++ ) {
 291     Node *m = *old_table++;
 292     if( !m || m == _sentinel ) continue;
 293     debug_only(m->exit_hash_lock()); // Unlock the node upon removal from old table.
 294     hash_insert(m);
 295   }
 296 }
 297 
 298 //------------------------------clear------------------------------------------
 299 // Clear all entries in _table to NULL but keep storage
 300 void  NodeHash::clear() {
 301 #ifdef ASSERT
 302   // Unlock all nodes upon removal from table.
 303   for (uint i = 0; i < _max; i++) {
 304     Node* n = _table[i];
 305     if (!n || n == _sentinel)  continue;
 306     n->exit_hash_lock();
 307   }
 308 #endif
 309 
 310   memset( _table, 0, _max * sizeof(Node*) );
 311 }
 312 
 313 //-----------------------remove_useless_nodes----------------------------------
 314 // Remove useless nodes from value table,
 315 // implementation does not depend on hash function
 316 void NodeHash::remove_useless_nodes(VectorSet &useful) {
 317 
 318   // Dead nodes in the hash table inherited from GVN should not replace
 319   // existing nodes, remove dead nodes.
 320   uint max = size();
 321   Node *sentinel_node = sentinel();
 322   for( uint i = 0; i < max; ++i ) {
 323     Node *n = at(i);
 324     if(n != NULL && n != sentinel_node && !useful.test(n->_idx)) {
 325       debug_only(n->exit_hash_lock()); // Unlock the node when removed
 326       _table[i] = sentinel_node;       // Replace with placeholder
 327     }
 328   }
 329 }
 330 
 331 
 332 void NodeHash::check_no_speculative_types() {
 333 #ifdef ASSERT
 334   uint max = size();
 335   Node *sentinel_node = sentinel();
 336   for (uint i = 0; i < max; ++i) {
 337     Node *n = at(i);
 338     if(n != NULL && n != sentinel_node && n->is_Type() && n->outcnt() > 0) {
 339       TypeNode* tn = n->as_Type();
 340       const Type* t = tn->type();
 341       const Type* t_no_spec = t->remove_speculative();
 342       assert(t == t_no_spec, "dead node in hash table or missed node during speculative cleanup");
 343     }
 344   }
 345 #endif
 346 }
 347 
 348 #ifndef PRODUCT
 349 //------------------------------dump-------------------------------------------
 350 // Dump statistics for the hash table
 351 void NodeHash::dump() {
 352   _total_inserts       += _inserts;
 353   _total_insert_probes += _insert_probes;
 354   if (PrintCompilation && PrintOptoStatistics && Verbose && (_inserts > 0)) {
 355     if (WizardMode) {
 356       for (uint i=0; i<_max; i++) {
 357         if (_table[i])
 358           tty->print("%d/%d/%d ",i,_table[i]->hash()&(_max-1),_table[i]->_idx);
 359       }
 360     }
 361     tty->print("\nGVN Hash stats:  %d grows to %d max_size\n", _grows, _max);
 362     tty->print("  %d/%d (%8.1f%% full)\n", _inserts, _max, (double)_inserts/_max*100.0);
 363     tty->print("  %dp/(%dh+%dm) (%8.2f probes/lookup)\n", _look_probes, _lookup_hits, _lookup_misses, (double)_look_probes/(_lookup_hits+_lookup_misses));
 364     tty->print("  %dp/%di (%8.2f probes/insert)\n", _total_insert_probes, _total_inserts, (double)_total_insert_probes/_total_inserts);
 365     // sentinels increase lookup cost, but not insert cost
 366     assert((_lookup_misses+_lookup_hits)*4+100 >= _look_probes, "bad hash function");
 367     assert( _inserts+(_inserts>>3) < _max, "table too full" );
 368     assert( _inserts*3+100 >= _insert_probes, "bad hash function" );
 369   }
 370 }
 371 
 372 Node *NodeHash::find_index(uint idx) { // For debugging
 373   // Find an entry by its index value
 374   for( uint i = 0; i < _max; i++ ) {
 375     Node *m = _table[i];
 376     if( !m || m == _sentinel ) continue;
 377     if( m->_idx == (uint)idx ) return m;
 378   }
 379   return NULL;
 380 }
 381 #endif
 382 
 383 #ifdef ASSERT
 384 NodeHash::~NodeHash() {
 385   // Unlock all nodes upon destruction of table.
 386   if (_table != (Node**)badAddress)  clear();
 387 }
 388 
 389 void NodeHash::operator=(const NodeHash& nh) {
 390   // Unlock all nodes upon replacement of table.
 391   if (&nh == this)  return;
 392   if (_table != (Node**)badAddress)  clear();
 393   memcpy((void*)this, (void*)&nh, sizeof(*this));
 394   // Do not increment hash_lock counts again.
 395   // Instead, be sure we never again use the source table.
 396   ((NodeHash*)&nh)->_table = (Node**)badAddress;
 397 }
 398 
 399 
 400 #endif
 401 
 402 
 403 //=============================================================================
 404 //------------------------------PhaseRemoveUseless-----------------------------
 405 // 1) Use a breadthfirst walk to collect useful nodes reachable from root.
 406 PhaseRemoveUseless::PhaseRemoveUseless(PhaseGVN *gvn, Unique_Node_List *worklist, PhaseNumber phase_num) : Phase(phase_num),
 407   _useful(Thread::current()->resource_area()) {
 408 
 409   // Implementation requires 'UseLoopSafepoints == true' and an edge from root
 410   // to each SafePointNode at a backward branch.  Inserted in add_safepoint().
 411   if( !UseLoopSafepoints || !OptoRemoveUseless ) return;
 412 
 413   // Identify nodes that are reachable from below, useful.
 414   C->identify_useful_nodes(_useful);
 415   // Update dead node list
 416   C->update_dead_node_list(_useful);
 417 
 418   // Remove all useless nodes from PhaseValues' recorded types
 419   // Must be done before disconnecting nodes to preserve hash-table-invariant
 420   gvn->remove_useless_nodes(_useful.member_set());
 421 
 422   // Remove all useless nodes from future worklist
 423   worklist->remove_useless_nodes(_useful.member_set());
 424 
 425   // Disconnect 'useless' nodes that are adjacent to useful nodes
 426   C->remove_useless_nodes(_useful);
 427 }
 428 
 429 //=============================================================================
 430 //------------------------------PhaseRenumberLive------------------------------
 431 // First, remove useless nodes (equivalent to identifying live nodes).
 432 // Then, renumber live nodes.
 433 //
 434 // The set of live nodes is returned by PhaseRemoveUseless in the _useful structure.
 435 // If the number of live nodes is 'x' (where 'x' == _useful.size()), then the
 436 // PhaseRenumberLive updates the node ID of each node (the _idx field) with a unique
 437 // value in the range [0, x).
 438 //
 439 // At the end of the PhaseRenumberLive phase, the compiler's count of unique nodes is
 440 // updated to 'x' and the list of dead nodes is reset (as there are no dead nodes).
 441 //
 442 // The PhaseRenumberLive phase updates two data structures with the new node IDs.
 443 // (1) The worklist is used by the PhaseIterGVN phase to identify nodes that must be
 444 // processed. A new worklist (with the updated node IDs) is returned in 'new_worklist'.
 445 // (2) Type information (the field PhaseGVN::_types) maps type information to each
 446 // node ID. The mapping is updated to use the new node IDs as well. Updated type
 447 // information is returned in PhaseGVN::_types.
 448 //
 449 // The PhaseRenumberLive phase does not preserve the order of elements in the worklist.
 450 //
 451 // Other data structures used by the compiler are not updated. The hash table for value
 452 // numbering (the field PhaseGVN::_table) is not updated because computing the hash
 453 // values is not based on node IDs. The field PhaseGVN::_nodes is not updated either
 454 // because it is empty wherever PhaseRenumberLive is used.
 455 PhaseRenumberLive::PhaseRenumberLive(PhaseGVN* gvn,
 456                                      Unique_Node_List* worklist, Unique_Node_List* new_worklist,
 457                                      PhaseNumber phase_num) :
 458   PhaseRemoveUseless(gvn, worklist, Remove_Useless_And_Renumber_Live),
 459   _new_type_array(C->comp_arena()),
 460   _old2new_map(C->unique(), C->unique(), -1),
 461   _delayed(Thread::current()->resource_area()),
 462   _is_pass_finished(false),
 463   _live_node_count(C->live_nodes())
 464 {
 465   assert(RenumberLiveNodes, "RenumberLiveNodes must be set to true for node renumbering to take place");
 466   assert(C->live_nodes() == _useful.size(), "the number of live nodes must match the number of useful nodes");
 467   assert(gvn->nodes_size() == 0, "GVN must not contain any nodes at this point");
 468   assert(_delayed.size() == 0, "should be empty");
 469 
 470   uint worklist_size = worklist->size();
 471 
 472   // Iterate over the set of live nodes.
 473   for (uint current_idx = 0; current_idx < _useful.size(); current_idx++) {
 474     Node* n = _useful.at(current_idx);
 475 
 476     bool in_worklist = false;
 477     if (worklist->member(n)) {
 478       in_worklist = true;
 479     }
 480 
 481     const Type* type = gvn->type_or_null(n);
 482     _new_type_array.map(current_idx, type);
 483 
 484     assert(_old2new_map.at(n->_idx) == -1, "already seen");
 485     _old2new_map.at_put(n->_idx, current_idx);
 486 
 487     n->set_idx(current_idx); // Update node ID.
 488 
 489     if (in_worklist) {
 490       new_worklist->push(n);
 491     }
 492 
 493     if (update_embedded_ids(n) < 0) {
 494       _delayed.push(n); // has embedded IDs; handle later
 495     }
 496   }
 497 
 498   assert(worklist_size == new_worklist->size(), "the new worklist must have the same size as the original worklist");
 499   assert(_live_node_count == _useful.size(), "all live nodes must be processed");
 500 
 501   _is_pass_finished = true; // pass finished; safe to process delayed updates
 502 
 503   while (_delayed.size() > 0) {
 504     Node* n = _delayed.pop();
 505     int no_of_updates = update_embedded_ids(n);
 506     assert(no_of_updates > 0, "should be updated");
 507   }
 508 
 509   // Replace the compiler's type information with the updated type information.
 510   gvn->replace_types(_new_type_array);
 511 
 512   // Update the unique node count of the compilation to the number of currently live nodes.
 513   C->set_unique(_live_node_count);
 514 
 515   // Set the dead node count to 0 and reset dead node list.
 516   C->reset_dead_node_list();
 517 }
 518 
 519 int PhaseRenumberLive::new_index(int old_idx) {
 520   assert(_is_pass_finished, "not finished");
 521   if (_old2new_map.at(old_idx) == -1) { // absent
 522     // Allocate a placeholder to preserve uniqueness
 523     _old2new_map.at_put(old_idx, _live_node_count);
 524     _live_node_count++;
 525   }
 526   return _old2new_map.at(old_idx);
 527 }
 528 
 529 int PhaseRenumberLive::update_embedded_ids(Node* n) {
 530   int no_of_updates = 0;
 531   if (n->is_Phi()) {
 532     PhiNode* phi = n->as_Phi();
 533     if (phi->_inst_id != -1) {
 534       if (!_is_pass_finished) {
 535         return -1; // delay
 536       }
 537       int new_idx = new_index(phi->_inst_id);
 538       assert(new_idx != -1, "");
 539       phi->_inst_id = new_idx;
 540       no_of_updates++;
 541     }
 542     if (phi->_inst_mem_id != -1) {
 543       if (!_is_pass_finished) {
 544         return -1; // delay
 545       }
 546       int new_idx = new_index(phi->_inst_mem_id);
 547       assert(new_idx != -1, "");
 548       phi->_inst_mem_id = new_idx;
 549       no_of_updates++;
 550     }
 551   }
 552 
 553   const Type* type = _new_type_array.fast_lookup(n->_idx);
 554   if (type != NULL && type->isa_oopptr() && type->is_oopptr()->is_known_instance()) {
 555     if (!_is_pass_finished) {
 556         return -1; // delay
 557     }
 558     int old_idx = type->is_oopptr()->instance_id();
 559     int new_idx = new_index(old_idx);
 560     const Type* new_type = type->is_oopptr()->with_instance_id(new_idx);
 561     _new_type_array.map(n->_idx, new_type);
 562     no_of_updates++;
 563   }
 564 
 565   return no_of_updates;
 566 }
 567 
 568 //=============================================================================
 569 //------------------------------PhaseTransform---------------------------------
 570 PhaseTransform::PhaseTransform( PhaseNumber pnum ) : Phase(pnum),
 571   _arena(Thread::current()->resource_area()),
 572   _nodes(_arena),
 573   _types(_arena)
 574 {
 575   init_con_caches();
 576 #ifndef PRODUCT
 577   clear_progress();
 578   clear_transforms();
 579   set_allow_progress(true);
 580 #endif
 581   // Force allocation for currently existing nodes
 582   _types.map(C->unique(), NULL);
 583 }
 584 
 585 //------------------------------PhaseTransform---------------------------------
 586 PhaseTransform::PhaseTransform( Arena *arena, PhaseNumber pnum ) : Phase(pnum),
 587   _arena(arena),
 588   _nodes(arena),
 589   _types(arena)
 590 {
 591   init_con_caches();
 592 #ifndef PRODUCT
 593   clear_progress();
 594   clear_transforms();
 595   set_allow_progress(true);
 596 #endif
 597   // Force allocation for currently existing nodes
 598   _types.map(C->unique(), NULL);
 599 }
 600 
 601 //------------------------------PhaseTransform---------------------------------
 602 // Initialize with previously generated type information
 603 PhaseTransform::PhaseTransform( PhaseTransform *pt, PhaseNumber pnum ) : Phase(pnum),
 604   _arena(pt->_arena),
 605   _nodes(pt->_nodes),
 606   _types(pt->_types)
 607 {
 608   init_con_caches();
 609 #ifndef PRODUCT
 610   clear_progress();
 611   clear_transforms();
 612   set_allow_progress(true);
 613 #endif
 614 }
 615 
 616 void PhaseTransform::init_con_caches() {
 617   memset(_icons,0,sizeof(_icons));
 618   memset(_lcons,0,sizeof(_lcons));
 619   memset(_zcons,0,sizeof(_zcons));
 620 }
 621 
 622 
 623 //--------------------------------find_int_type--------------------------------
 624 const TypeInt* PhaseTransform::find_int_type(Node* n) {
 625   if (n == NULL)  return NULL;
 626   // Call type_or_null(n) to determine node's type since we might be in
 627   // parse phase and call n->Value() may return wrong type.
 628   // (For example, a phi node at the beginning of loop parsing is not ready.)
 629   const Type* t = type_or_null(n);
 630   if (t == NULL)  return NULL;
 631   return t->isa_int();
 632 }
 633 
 634 
 635 //-------------------------------find_long_type--------------------------------
 636 const TypeLong* PhaseTransform::find_long_type(Node* n) {
 637   if (n == NULL)  return NULL;
 638   // (See comment above on type_or_null.)
 639   const Type* t = type_or_null(n);
 640   if (t == NULL)  return NULL;
 641   return t->isa_long();
 642 }
 643 
 644 
 645 #ifndef PRODUCT
 646 void PhaseTransform::dump_old2new_map() const {
 647   _nodes.dump();
 648 }
 649 
 650 void PhaseTransform::dump_new( uint nidx ) const {
 651   for( uint i=0; i<_nodes.Size(); i++ )
 652     if( _nodes[i] && _nodes[i]->_idx == nidx ) {
 653       _nodes[i]->dump();
 654       tty->cr();
 655       tty->print_cr("Old index= %d",i);
 656       return;
 657     }
 658   tty->print_cr("Node %d not found in the new indices", nidx);
 659 }
 660 
 661 //------------------------------dump_types-------------------------------------
 662 void PhaseTransform::dump_types( ) const {
 663   _types.dump();
 664 }
 665 
 666 //------------------------------dump_nodes_and_types---------------------------
 667 void PhaseTransform::dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl) {
 668   VectorSet visited(Thread::current()->resource_area());
 669   dump_nodes_and_types_recur( root, depth, only_ctrl, visited );
 670 }
 671 
 672 //------------------------------dump_nodes_and_types_recur---------------------
 673 void PhaseTransform::dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited) {
 674   if( !n ) return;
 675   if( depth == 0 ) return;
 676   if( visited.test_set(n->_idx) ) return;
 677   for( uint i=0; i<n->len(); i++ ) {
 678     if( only_ctrl && !(n->is_Region()) && i != TypeFunc::Control ) continue;
 679     dump_nodes_and_types_recur( n->in(i), depth-1, only_ctrl, visited );
 680   }
 681   n->dump();
 682   if (type_or_null(n) != NULL) {
 683     tty->print("      "); type(n)->dump(); tty->cr();
 684   }
 685 }
 686 
 687 #endif
 688 
 689 
 690 //=============================================================================
 691 //------------------------------PhaseValues------------------------------------
 692 // Set minimum table size to "255"
 693 PhaseValues::PhaseValues( Arena *arena, uint est_max_size ) : PhaseTransform(arena, GVN), _table(arena, est_max_size) {
 694   NOT_PRODUCT( clear_new_values(); )
 695 }
 696 
 697 //------------------------------PhaseValues------------------------------------
 698 // Set minimum table size to "255"
 699 PhaseValues::PhaseValues( PhaseValues *ptv ) : PhaseTransform( ptv, GVN ),
 700   _table(&ptv->_table) {
 701   NOT_PRODUCT( clear_new_values(); )
 702 }
 703 
 704 //------------------------------~PhaseValues-----------------------------------
 705 #ifndef PRODUCT
 706 PhaseValues::~PhaseValues() {
 707   _table.dump();
 708 
 709   // Statistics for value progress and efficiency
 710   if( PrintCompilation && Verbose && WizardMode ) {
 711     tty->print("\n%sValues: %d nodes ---> %d/%d (%d)",
 712       is_IterGVN() ? "Iter" : "    ", C->unique(), made_progress(), made_transforms(), made_new_values());
 713     if( made_transforms() != 0 ) {
 714       tty->print_cr("  ratio %f", made_progress()/(float)made_transforms() );
 715     } else {
 716       tty->cr();
 717     }
 718   }
 719 }
 720 #endif
 721 
 722 //------------------------------makecon----------------------------------------
 723 ConNode* PhaseTransform::makecon(const Type *t) {
 724   assert(t->singleton(), "must be a constant");
 725   assert(!t->empty() || t == Type::TOP, "must not be vacuous range");
 726   switch (t->base()) {  // fast paths
 727   case Type::Half:
 728   case Type::Top:  return (ConNode*) C->top();
 729   case Type::Int:  return intcon( t->is_int()->get_con() );
 730   case Type::Long: return longcon( t->is_long()->get_con() );
 731   default:         break;
 732   }
 733   if (t->is_zero_type())
 734     return zerocon(t->basic_type());
 735   return uncached_makecon(t);
 736 }
 737 
 738 //--------------------------uncached_makecon-----------------------------------
 739 // Make an idealized constant - one of ConINode, ConPNode, etc.
 740 ConNode* PhaseValues::uncached_makecon(const Type *t) {
 741   assert(t->singleton(), "must be a constant");
 742   ConNode* x = ConNode::make(t);
 743   ConNode* k = (ConNode*)hash_find_insert(x); // Value numbering
 744   if (k == NULL) {
 745     set_type(x, t);             // Missed, provide type mapping
 746     GrowableArray<Node_Notes*>* nna = C->node_note_array();
 747     if (nna != NULL) {
 748       Node_Notes* loc = C->locate_node_notes(nna, x->_idx, true);
 749       loc->clear(); // do not put debug info on constants
 750     }
 751   } else {
 752     x->destruct();              // Hit, destroy duplicate constant
 753     x = k;                      // use existing constant
 754   }
 755   return x;
 756 }
 757 
 758 //------------------------------intcon-----------------------------------------
 759 // Fast integer constant.  Same as "transform(new ConINode(TypeInt::make(i)))"
 760 ConINode* PhaseTransform::intcon(jint i) {
 761   // Small integer?  Check cache! Check that cached node is not dead
 762   if (i >= _icon_min && i <= _icon_max) {
 763     ConINode* icon = _icons[i-_icon_min];
 764     if (icon != NULL && icon->in(TypeFunc::Control) != NULL)
 765       return icon;
 766   }
 767   ConINode* icon = (ConINode*) uncached_makecon(TypeInt::make(i));
 768   assert(icon->is_Con(), "");
 769   if (i >= _icon_min && i <= _icon_max)
 770     _icons[i-_icon_min] = icon;   // Cache small integers
 771   return icon;
 772 }
 773 
 774 //------------------------------longcon----------------------------------------
 775 // Fast long constant.
 776 ConLNode* PhaseTransform::longcon(jlong l) {
 777   // Small integer?  Check cache! Check that cached node is not dead
 778   if (l >= _lcon_min && l <= _lcon_max) {
 779     ConLNode* lcon = _lcons[l-_lcon_min];
 780     if (lcon != NULL && lcon->in(TypeFunc::Control) != NULL)
 781       return lcon;
 782   }
 783   ConLNode* lcon = (ConLNode*) uncached_makecon(TypeLong::make(l));
 784   assert(lcon->is_Con(), "");
 785   if (l >= _lcon_min && l <= _lcon_max)
 786     _lcons[l-_lcon_min] = lcon;      // Cache small integers
 787   return lcon;
 788 }
 789 
 790 //------------------------------zerocon-----------------------------------------
 791 // Fast zero or null constant. Same as "transform(ConNode::make(Type::get_zero_type(bt)))"
 792 ConNode* PhaseTransform::zerocon(BasicType bt) {
 793   assert((uint)bt <= _zcon_max, "domain check");
 794   ConNode* zcon = _zcons[bt];
 795   if (zcon != NULL && zcon->in(TypeFunc::Control) != NULL)
 796     return zcon;
 797   zcon = (ConNode*) uncached_makecon(Type::get_zero_type(bt));
 798   _zcons[bt] = zcon;
 799   return zcon;
 800 }
 801 
 802 
 803 
 804 //=============================================================================
 805 Node* PhaseGVN::apply_ideal(Node* k, bool can_reshape) {
 806   Node* i = BarrierSet::barrier_set()->barrier_set_c2()->ideal_node(this, k, can_reshape);
 807   if (i == NULL) {
 808     i = k->Ideal(this, can_reshape);
 809   }
 810   return i;
 811 }
 812 
 813 Node* PhaseGVN::apply_identity(Node* k) {
 814   Node* i = BarrierSet::barrier_set()->barrier_set_c2()->identity_node(this, k);
 815   if (i == k) {
 816     i = k->Identity(this);
 817   }
 818   return i;
 819 }
 820 
 821 //------------------------------transform--------------------------------------
 822 // Return a node which computes the same function as this node, but in a
 823 // faster or cheaper fashion.
 824 Node *PhaseGVN::transform( Node *n ) {
 825   return transform_no_reclaim(n);
 826 }
 827 
 828 //------------------------------transform--------------------------------------
 829 // Return a node which computes the same function as this node, but
 830 // in a faster or cheaper fashion.
 831 Node *PhaseGVN::transform_no_reclaim( Node *n ) {
 832   NOT_PRODUCT( set_transforms(); )
 833 
 834   // Apply the Ideal call in a loop until it no longer applies
 835   Node *k = n;
 836   NOT_PRODUCT( uint loop_count = 0; )
 837   while( 1 ) {
 838     Node *i = apply_ideal(k, /*can_reshape=*/false);
 839     if( !i ) break;
 840     assert( i->_idx >= k->_idx, "Idealize should return new nodes, use Identity to return old nodes" );
 841     k = i;
 842     assert(loop_count++ < K, "infinite loop in PhaseGVN::transform");
 843   }
 844   NOT_PRODUCT( if( loop_count != 0 ) { set_progress(); } )
 845 
 846 
 847   // If brand new node, make space in type array.
 848   ensure_type_or_null(k);
 849 
 850   // Since I just called 'Value' to compute the set of run-time values
 851   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
 852   // cache Value.  Later requests for the local phase->type of this Node can
 853   // use the cached Value instead of suffering with 'bottom_type'.
 854   const Type *t = k->Value(this); // Get runtime Value set
 855   assert(t != NULL, "value sanity");
 856   if (type_or_null(k) != t) {
 857 #ifndef PRODUCT
 858     // Do not count initial visit to node as a transformation
 859     if (type_or_null(k) == NULL) {
 860       inc_new_values();
 861       set_progress();
 862     }
 863 #endif
 864     set_type(k, t);
 865     // If k is a TypeNode, capture any more-precise type permanently into Node
 866     k->raise_bottom_type(t);
 867   }
 868 
 869   if( t->singleton() && !k->is_Con() ) {
 870     NOT_PRODUCT( set_progress(); )
 871     return makecon(t);          // Turn into a constant
 872   }
 873 
 874   // Now check for Identities
 875   Node *i = apply_identity(k);  // Look for a nearby replacement
 876   if( i != k ) {                // Found? Return replacement!
 877     NOT_PRODUCT( set_progress(); )
 878     return i;
 879   }
 880 
 881   // Global Value Numbering
 882   i = hash_find_insert(k);      // Insert if new
 883   if( i && (i != k) ) {
 884     // Return the pre-existing node
 885     NOT_PRODUCT( set_progress(); )
 886     return i;
 887   }
 888 
 889   // Return Idealized original
 890   return k;
 891 }
 892 
 893 bool PhaseGVN::is_dominator_helper(Node *d, Node *n, bool linear_only) {
 894   if (d->is_top() || n->is_top()) {
 895     return false;
 896   }
 897   assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
 898   int i = 0;
 899   while (d != n) {
 900     n = IfNode::up_one_dom(n, linear_only);
 901     i++;
 902     if (n == NULL || i >= 10) {
 903       return false;
 904     }
 905   }
 906   return true;
 907 }
 908 
 909 #ifdef ASSERT
 910 //------------------------------dead_loop_check--------------------------------
 911 // Check for a simple dead loop when a data node references itself directly
 912 // or through an other data node excluding cons and phis.
 913 void PhaseGVN::dead_loop_check( Node *n ) {
 914   // Phi may reference itself in a loop
 915   if (n != NULL && !n->is_dead_loop_safe() && !n->is_CFG()) {
 916     // Do 2 levels check and only data inputs.
 917     bool no_dead_loop = true;
 918     uint cnt = n->req();
 919     for (uint i = 1; i < cnt && no_dead_loop; i++) {
 920       Node *in = n->in(i);
 921       if (in == n) {
 922         no_dead_loop = false;
 923       } else if (in != NULL && !in->is_dead_loop_safe()) {
 924         uint icnt = in->req();
 925         for (uint j = 1; j < icnt && no_dead_loop; j++) {
 926           if (in->in(j) == n || in->in(j) == in)
 927             no_dead_loop = false;
 928         }
 929       }
 930     }
 931     if (!no_dead_loop) n->dump(3);
 932     assert(no_dead_loop, "dead loop detected");
 933   }
 934 }
 935 #endif
 936 
 937 //=============================================================================
 938 //------------------------------PhaseIterGVN-----------------------------------
 939 // Initialize with previous PhaseIterGVN info; used by PhaseCCP
 940 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn ) : PhaseGVN(igvn),
 941                                                    _delay_transform(igvn->_delay_transform),
 942                                                    _stack( igvn->_stack ),
 943                                                    _worklist( igvn->_worklist )
 944 {
 945 }
 946 
 947 //------------------------------PhaseIterGVN-----------------------------------
 948 // Initialize with previous PhaseGVN info from Parser
 949 PhaseIterGVN::PhaseIterGVN( PhaseGVN *gvn ) : PhaseGVN(gvn),
 950                                               _delay_transform(false),
 951 // TODO: Before incremental inlining it was allocated only once and it was fine. Now that
 952 //       the constructor is used in incremental inlining, this consumes too much memory:
 953 //                                            _stack(C->live_nodes() >> 1),
 954 //       So, as a band-aid, we replace this by:
 955                                               _stack(C->comp_arena(), 32),
 956                                               _worklist(*C->for_igvn())
 957 {
 958   uint max;
 959 
 960   // Dead nodes in the hash table inherited from GVN were not treated as
 961   // roots during def-use info creation; hence they represent an invisible
 962   // use.  Clear them out.
 963   max = _table.size();
 964   for( uint i = 0; i < max; ++i ) {
 965     Node *n = _table.at(i);
 966     if(n != NULL && n != _table.sentinel() && n->outcnt() == 0) {
 967       if( n->is_top() ) continue;
 968       assert( false, "Parse::remove_useless_nodes missed this node");
 969       hash_delete(n);
 970     }
 971   }
 972 
 973   // Any Phis or Regions on the worklist probably had uses that could not
 974   // make more progress because the uses were made while the Phis and Regions
 975   // were in half-built states.  Put all uses of Phis and Regions on worklist.
 976   max = _worklist.size();
 977   for( uint j = 0; j < max; j++ ) {
 978     Node *n = _worklist.at(j);
 979     uint uop = n->Opcode();
 980     if( uop == Op_Phi || uop == Op_Region ||
 981         n->is_Type() ||
 982         n->is_Mem() )
 983       add_users_to_worklist(n);
 984   }
 985 }
 986 
 987 /**
 988  * Initialize worklist for each node.
 989  */
 990 void PhaseIterGVN::init_worklist(Node* first) {
 991   Unique_Node_List to_process;
 992   to_process.push(first);
 993 
 994   while (to_process.size() > 0) {
 995     Node* n = to_process.pop();
 996     if (!_worklist.member(n)) {
 997       _worklist.push(n);
 998 
 999       uint cnt = n->req();
1000       for(uint i = 0; i < cnt; i++) {
1001         Node* m = n->in(i);
1002         if (m != NULL) {
1003           to_process.push(m);
1004         }
1005       }
1006     }
1007   }
1008 }
1009 
1010 #ifndef PRODUCT
1011 void PhaseIterGVN::verify_step(Node* n) {
1012   if (VerifyIterativeGVN) {
1013     _verify_window[_verify_counter % _verify_window_size] = n;
1014     ++_verify_counter;
1015     ResourceMark rm;
1016     ResourceArea* area = Thread::current()->resource_area();
1017     VectorSet old_space(area), new_space(area);
1018     if (C->unique() < 1000 ||
1019         0 == _verify_counter % (C->unique() < 10000 ? 10 : 100)) {
1020       ++_verify_full_passes;
1021       Node::verify_recur(C->root(), -1, old_space, new_space);
1022     }
1023     const int verify_depth = 4;
1024     for ( int i = 0; i < _verify_window_size; i++ ) {
1025       Node* n = _verify_window[i];
1026       if ( n == NULL )  continue;
1027       if( n->in(0) == NodeSentinel ) {  // xform_idom
1028         _verify_window[i] = n->in(1);
1029         --i; continue;
1030       }
1031       // Typical fanout is 1-2, so this call visits about 6 nodes.
1032       Node::verify_recur(n, verify_depth, old_space, new_space);
1033     }
1034   }
1035 }
1036 
1037 void PhaseIterGVN::trace_PhaseIterGVN(Node* n, Node* nn, const Type* oldtype) {
1038   if (TraceIterativeGVN) {
1039     uint wlsize = _worklist.size();
1040     const Type* newtype = type_or_null(n);
1041     if (nn != n) {
1042       // print old node
1043       tty->print("< ");
1044       if (oldtype != newtype && oldtype != NULL) {
1045         oldtype->dump();
1046       }
1047       do { tty->print("\t"); } while (tty->position() < 16);
1048       tty->print("<");
1049       n->dump();
1050     }
1051     if (oldtype != newtype || nn != n) {
1052       // print new node and/or new type
1053       if (oldtype == NULL) {
1054         tty->print("* ");
1055       } else if (nn != n) {
1056         tty->print("> ");
1057       } else {
1058         tty->print("= ");
1059       }
1060       if (newtype == NULL) {
1061         tty->print("null");
1062       } else {
1063         newtype->dump();
1064       }
1065       do { tty->print("\t"); } while (tty->position() < 16);
1066       nn->dump();
1067     }
1068     if (Verbose && wlsize < _worklist.size()) {
1069       tty->print("  Push {");
1070       while (wlsize != _worklist.size()) {
1071         Node* pushed = _worklist.at(wlsize++);
1072         tty->print(" %d", pushed->_idx);
1073       }
1074       tty->print_cr(" }");
1075     }
1076     if (nn != n) {
1077       // ignore n, it might be subsumed
1078       verify_step((Node*) NULL);
1079     }
1080   }
1081 }
1082 
1083 void PhaseIterGVN::init_verifyPhaseIterGVN() {
1084   _verify_counter = 0;
1085   _verify_full_passes = 0;
1086   for (int i = 0; i < _verify_window_size; i++) {
1087     _verify_window[i] = NULL;
1088   }
1089 #ifdef ASSERT
1090   // Verify that all modified nodes are on _worklist
1091   Unique_Node_List* modified_list = C->modified_nodes();
1092   while (modified_list != NULL && modified_list->size()) {
1093     Node* n = modified_list->pop();
1094     if (n->outcnt() != 0 && !n->is_Con() && !_worklist.member(n)) {
1095       n->dump();
1096       assert(false, "modified node is not on IGVN._worklist");
1097     }
1098   }
1099 #endif
1100 }
1101 
1102 void PhaseIterGVN::verify_PhaseIterGVN() {
1103 #ifdef ASSERT
1104   // Verify nodes with changed inputs.
1105   Unique_Node_List* modified_list = C->modified_nodes();
1106   while (modified_list != NULL && modified_list->size()) {
1107     Node* n = modified_list->pop();
1108     if (n->outcnt() != 0 && !n->is_Con()) { // skip dead and Con nodes
1109       n->dump();
1110       assert(false, "modified node was not processed by IGVN.transform_old()");
1111     }
1112   }
1113 #endif
1114 
1115   C->verify_graph_edges();
1116   if (VerifyIterativeGVN && PrintOpto) {
1117     if (_verify_counter == _verify_full_passes) {
1118       tty->print_cr("VerifyIterativeGVN: %d transforms and verify passes",
1119                     (int) _verify_full_passes);
1120     } else {
1121       tty->print_cr("VerifyIterativeGVN: %d transforms, %d full verify passes",
1122                   (int) _verify_counter, (int) _verify_full_passes);
1123     }
1124   }
1125 
1126 #ifdef ASSERT
1127   while (modified_list->size()) {
1128     Node* n = modified_list->pop();
1129     n->dump();
1130     assert(false, "VerifyIterativeGVN: new modified node was added");
1131   }
1132 #endif
1133 }
1134 #endif /* PRODUCT */
1135 
1136 #ifdef ASSERT
1137 /**
1138  * Dumps information that can help to debug the problem. A debug
1139  * build fails with an assert.
1140  */
1141 void PhaseIterGVN::dump_infinite_loop_info(Node* n) {
1142   n->dump(4);
1143   _worklist.dump();
1144   assert(false, "infinite loop in PhaseIterGVN::optimize");
1145 }
1146 
1147 /**
1148  * Prints out information about IGVN if the 'verbose' option is used.
1149  */
1150 void PhaseIterGVN::trace_PhaseIterGVN_verbose(Node* n, int num_processed) {
1151   if (TraceIterativeGVN && Verbose) {
1152     tty->print("  Pop ");
1153     n->dump();
1154     if ((num_processed % 100) == 0) {
1155       _worklist.print_set();
1156     }
1157   }
1158 }
1159 #endif /* ASSERT */
1160 
1161 void PhaseIterGVN::optimize() {
1162   DEBUG_ONLY(uint num_processed  = 0;)
1163   NOT_PRODUCT(init_verifyPhaseIterGVN();)
1164 
1165   uint loop_count = 0;
1166   // Pull from worklist and transform the node. If the node has changed,
1167   // update edge info and put uses on worklist.
1168   while(_worklist.size()) {
1169     if (C->check_node_count(NodeLimitFudgeFactor * 2, "Out of nodes")) {
1170       return;
1171     }
1172     Node* n  = _worklist.pop();
1173     if (++loop_count >= K * C->live_nodes()) {
1174       DEBUG_ONLY(dump_infinite_loop_info(n);)
1175       C->record_method_not_compilable("infinite loop in PhaseIterGVN::optimize");
1176       return;
1177     }
1178     DEBUG_ONLY(trace_PhaseIterGVN_verbose(n, num_processed++);)
1179     if (n->outcnt() != 0) {
1180       NOT_PRODUCT(const Type* oldtype = type_or_null(n));
1181       // Do the transformation
1182       Node* nn = transform_old(n);
1183       NOT_PRODUCT(trace_PhaseIterGVN(n, nn, oldtype);)
1184     } else if (!n->is_top()) {
1185       remove_dead_node(n);
1186     }
1187   }
1188   NOT_PRODUCT(verify_PhaseIterGVN();)
1189 }
1190 
1191 
1192 /**
1193  * Register a new node with the optimizer.  Update the types array, the def-use
1194  * info.  Put on worklist.
1195  */
1196 Node* PhaseIterGVN::register_new_node_with_optimizer(Node* n, Node* orig) {
1197   set_type_bottom(n);
1198   _worklist.push(n);
1199   if (orig != NULL)  C->copy_node_notes_to(n, orig);
1200   return n;
1201 }
1202 
1203 //------------------------------transform--------------------------------------
1204 // Non-recursive: idealize Node 'n' with respect to its inputs and its value
1205 Node *PhaseIterGVN::transform( Node *n ) {
1206   // If brand new node, make space in type array, and give it a type.
1207   ensure_type_or_null(n);
1208   if (type_or_null(n) == NULL) {
1209     set_type_bottom(n);
1210   }
1211 
1212   if (_delay_transform) {
1213     // Add the node to the worklist but don't optimize for now
1214     _worklist.push(n);
1215     return n;
1216   }
1217 
1218   return transform_old(n);
1219 }
1220 
1221 Node *PhaseIterGVN::transform_old(Node* n) {
1222   DEBUG_ONLY(uint loop_count = 0;);
1223   NOT_PRODUCT(set_transforms());
1224 
1225   // Remove 'n' from hash table in case it gets modified
1226   _table.hash_delete(n);
1227   if (VerifyIterativeGVN) {
1228    assert(!_table.find_index(n->_idx), "found duplicate entry in table");
1229   }
1230 
1231   // Apply the Ideal call in a loop until it no longer applies
1232   Node* k = n;
1233   DEBUG_ONLY(dead_loop_check(k);)
1234   DEBUG_ONLY(bool is_new = (k->outcnt() == 0);)
1235   C->remove_modified_node(k);
1236   Node* i = apply_ideal(k, /*can_reshape=*/true);
1237   assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes");
1238 #ifndef PRODUCT
1239   verify_step(k);
1240 #endif
1241 
1242   while (i != NULL) {
1243 #ifdef ASSERT
1244     if (loop_count >= K) {
1245       dump_infinite_loop_info(i);
1246     }
1247     loop_count++;
1248 #endif
1249     assert((i->_idx >= k->_idx) || i->is_top(), "Idealize should return new nodes, use Identity to return old nodes");
1250     // Made a change; put users of original Node on worklist
1251     add_users_to_worklist(k);
1252     // Replacing root of transform tree?
1253     if (k != i) {
1254       // Make users of old Node now use new.
1255       subsume_node(k, i);
1256       k = i;
1257     }
1258     DEBUG_ONLY(dead_loop_check(k);)
1259     // Try idealizing again
1260     DEBUG_ONLY(is_new = (k->outcnt() == 0);)
1261     C->remove_modified_node(k);
1262     i = apply_ideal(k, /*can_reshape=*/true);
1263     assert(i != k || is_new || (i->outcnt() > 0), "don't return dead nodes");
1264 #ifndef PRODUCT
1265     verify_step(k);
1266 #endif
1267   }
1268 
1269   // If brand new node, make space in type array.
1270   ensure_type_or_null(k);
1271 
1272   // See what kind of values 'k' takes on at runtime
1273   const Type* t = k->Value(this);
1274   assert(t != NULL, "value sanity");
1275 
1276   // Since I just called 'Value' to compute the set of run-time values
1277   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
1278   // cache Value.  Later requests for the local phase->type of this Node can
1279   // use the cached Value instead of suffering with 'bottom_type'.
1280   if (type_or_null(k) != t) {
1281 #ifndef PRODUCT
1282     inc_new_values();
1283     set_progress();
1284 #endif
1285     set_type(k, t);
1286     // If k is a TypeNode, capture any more-precise type permanently into Node
1287     k->raise_bottom_type(t);
1288     // Move users of node to worklist
1289     add_users_to_worklist(k);
1290   }
1291   // If 'k' computes a constant, replace it with a constant
1292   if (t->singleton() && !k->is_Con()) {
1293     NOT_PRODUCT(set_progress();)
1294     Node* con = makecon(t);     // Make a constant
1295     add_users_to_worklist(k);
1296     subsume_node(k, con);       // Everybody using k now uses con
1297     return con;
1298   }
1299 
1300   // Now check for Identities
1301   i = apply_identity(k);      // Look for a nearby replacement
1302   if (i != k) {                // Found? Return replacement!
1303     NOT_PRODUCT(set_progress();)
1304     add_users_to_worklist(k);
1305     subsume_node(k, i);       // Everybody using k now uses i
1306     return i;
1307   }
1308 
1309   // Global Value Numbering
1310   i = hash_find_insert(k);      // Check for pre-existing node
1311   if (i && (i != k)) {
1312     // Return the pre-existing node if it isn't dead
1313     NOT_PRODUCT(set_progress();)
1314     add_users_to_worklist(k);
1315     subsume_node(k, i);       // Everybody using k now uses i
1316     return i;
1317   }
1318 
1319   // Return Idealized original
1320   return k;
1321 }
1322 
1323 //---------------------------------saturate------------------------------------
1324 const Type* PhaseIterGVN::saturate(const Type* new_type, const Type* old_type,
1325                                    const Type* limit_type) const {
1326   return new_type->narrow(old_type);
1327 }
1328 
1329 //------------------------------remove_globally_dead_node----------------------
1330 // Kill a globally dead Node.  All uses are also globally dead and are
1331 // aggressively trimmed.
1332 void PhaseIterGVN::remove_globally_dead_node( Node *dead ) {
1333   enum DeleteProgress {
1334     PROCESS_INPUTS,
1335     PROCESS_OUTPUTS
1336   };
1337   assert(_stack.is_empty(), "not empty");
1338   _stack.push(dead, PROCESS_INPUTS);
1339 
1340   while (_stack.is_nonempty()) {
1341     dead = _stack.node();
1342     if (dead->Opcode() == Op_SafePoint) {
1343       dead->as_SafePoint()->disconnect_from_root(this);
1344     }
1345     uint progress_state = _stack.index();
1346     assert(dead != C->root(), "killing root, eh?");
1347     assert(!dead->is_top(), "add check for top when pushing");
1348     NOT_PRODUCT( set_progress(); )
1349     if (progress_state == PROCESS_INPUTS) {
1350       // After following inputs, continue to outputs
1351       _stack.set_index(PROCESS_OUTPUTS);
1352       if (!dead->is_Con()) { // Don't kill cons but uses
1353         bool recurse = false;
1354         // Remove from hash table
1355         _table.hash_delete( dead );
1356         // Smash all inputs to 'dead', isolating him completely
1357         for (uint i = 0; i < dead->req(); i++) {
1358           Node *in = dead->in(i);
1359           if (in != NULL && in != C->top()) {  // Points to something?
1360             int nrep = dead->replace_edge(in, NULL);  // Kill edges
1361             assert((nrep > 0), "sanity");
1362             if (in->outcnt() == 0) { // Made input go dead?
1363               _stack.push(in, PROCESS_INPUTS); // Recursively remove
1364               recurse = true;
1365             } else if (in->outcnt() == 1 &&
1366                        in->has_special_unique_user()) {
1367               _worklist.push(in->unique_out());
1368             } else if (in->outcnt() <= 2 && dead->is_Phi()) {
1369               if (in->Opcode() == Op_Region) {
1370                 _worklist.push(in);
1371               } else if (in->is_Store()) {
1372                 DUIterator_Fast imax, i = in->fast_outs(imax);
1373                 _worklist.push(in->fast_out(i));
1374                 i++;
1375                 if (in->outcnt() == 2) {
1376                   _worklist.push(in->fast_out(i));
1377                   i++;
1378                 }
1379                 assert(!(i < imax), "sanity");
1380               }
1381             } else {
1382               BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(this, in);
1383             }
1384             if (ReduceFieldZeroing && dead->is_Load() && i == MemNode::Memory &&
1385                 in->is_Proj() && in->in(0) != NULL && in->in(0)->is_Initialize()) {
1386               // A Load that directly follows an InitializeNode is
1387               // going away. The Stores that follow are candidates
1388               // again to be captured by the InitializeNode.
1389               for (DUIterator_Fast jmax, j = in->fast_outs(jmax); j < jmax; j++) {
1390                 Node *n = in->fast_out(j);
1391                 if (n->is_Store()) {
1392                   _worklist.push(n);
1393                 }
1394               }
1395             }
1396           } // if (in != NULL && in != C->top())
1397         } // for (uint i = 0; i < dead->req(); i++)
1398         if (recurse) {
1399           continue;
1400         }
1401       } // if (!dead->is_Con())
1402     } // if (progress_state == PROCESS_INPUTS)
1403 
1404     // Aggressively kill globally dead uses
1405     // (Rather than pushing all the outs at once, we push one at a time,
1406     // plus the parent to resume later, because of the indefinite number
1407     // of edge deletions per loop trip.)
1408     if (dead->outcnt() > 0) {
1409       // Recursively remove output edges
1410       _stack.push(dead->raw_out(0), PROCESS_INPUTS);
1411     } else {
1412       // Finished disconnecting all input and output edges.
1413       _stack.pop();
1414       // Remove dead node from iterative worklist
1415       _worklist.remove(dead);
1416       C->remove_modified_node(dead);
1417       // Constant node that has no out-edges and has only one in-edge from
1418       // root is usually dead. However, sometimes reshaping walk makes
1419       // it reachable by adding use edges. So, we will NOT count Con nodes
1420       // as dead to be conservative about the dead node count at any
1421       // given time.
1422       if (!dead->is_Con()) {
1423         C->record_dead_node(dead->_idx);
1424       }
1425       if (dead->is_macro()) {
1426         C->remove_macro_node(dead);
1427       }
1428       if (dead->is_expensive()) {
1429         C->remove_expensive_node(dead);
1430       }
1431       CastIINode* cast = dead->isa_CastII();
1432       if (cast != NULL && cast->has_range_check()) {
1433         C->remove_range_check_cast(cast);
1434       }
1435       if (dead->Opcode() == Op_Opaque4) {
1436         C->remove_opaque4_node(dead);
1437       }
1438       if (dead->is_ValueTypeBase()) {
1439         C->remove_value_type(dead);
1440       }
1441       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1442       bs->unregister_potential_barrier_node(dead);
1443     }
1444   } // while (_stack.is_nonempty())
1445 }
1446 
1447 //------------------------------subsume_node-----------------------------------
1448 // Remove users from node 'old' and add them to node 'nn'.
1449 void PhaseIterGVN::subsume_node( Node *old, Node *nn ) {
1450   if (old->Opcode() == Op_SafePoint) {
1451     old->as_SafePoint()->disconnect_from_root(this);
1452   }
1453   assert( old != hash_find(old), "should already been removed" );
1454   assert( old != C->top(), "cannot subsume top node");
1455   // Copy debug or profile information to the new version:
1456   C->copy_node_notes_to(nn, old);
1457   // Move users of node 'old' to node 'nn'
1458   for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) {
1459     Node* use = old->last_out(i);  // for each use...
1460     // use might need re-hashing (but it won't if it's a new node)
1461     rehash_node_delayed(use);
1462     // Update use-def info as well
1463     // We remove all occurrences of old within use->in,
1464     // so as to avoid rehashing any node more than once.
1465     // The hash table probe swamps any outer loop overhead.
1466     uint num_edges = 0;
1467     for (uint jmax = use->len(), j = 0; j < jmax; j++) {
1468       if (use->in(j) == old) {
1469         use->set_req(j, nn);
1470         ++num_edges;
1471       }
1472     }
1473     i -= num_edges;    // we deleted 1 or more copies of this edge
1474   }
1475 
1476   // Search for instance field data PhiNodes in the same region pointing to the old
1477   // memory PhiNode and update their instance memory ids to point to the new node.
1478   if (old->is_Phi() && old->as_Phi()->type()->has_memory() && old->in(0) != NULL) {
1479     Node* region = old->in(0);
1480     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1481       PhiNode* phi = region->fast_out(i)->isa_Phi();
1482       if (phi != NULL && phi->inst_mem_id() == (int)old->_idx) {
1483         phi->set_inst_mem_id((int)nn->_idx);
1484       }
1485     }
1486   }
1487 
1488   // Smash all inputs to 'old', isolating him completely
1489   Node *temp = new Node(1);
1490   temp->init_req(0,nn);     // Add a use to nn to prevent him from dying
1491   remove_dead_node( old );
1492   temp->del_req(0);         // Yank bogus edge
1493 #ifndef PRODUCT
1494   if( VerifyIterativeGVN ) {
1495     for ( int i = 0; i < _verify_window_size; i++ ) {
1496       if ( _verify_window[i] == old )
1497         _verify_window[i] = nn;
1498     }
1499   }
1500 #endif
1501   _worklist.remove(temp);   // this can be necessary
1502   temp->destruct();         // reuse the _idx of this little guy
1503 }
1504 
1505 void PhaseIterGVN::replace_in_uses(Node* n, Node* m) {
1506   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1507     Node* u = n->fast_out(i);
1508     if (u != n) {
1509       rehash_node_delayed(u);
1510       int nb = u->replace_edge(n, m);
1511       --i, imax -= nb;
1512     }
1513   }
1514 }
1515 
1516 //------------------------------add_users_to_worklist--------------------------
1517 void PhaseIterGVN::add_users_to_worklist0( Node *n ) {
1518   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1519     _worklist.push(n->fast_out(i));  // Push on worklist
1520   }
1521 }
1522 
1523 // Return counted loop Phi if as a counted loop exit condition, cmp
1524 // compares the the induction variable with n
1525 static PhiNode* countedloop_phi_from_cmp(CmpINode* cmp, Node* n) {
1526   for (DUIterator_Fast imax, i = cmp->fast_outs(imax); i < imax; i++) {
1527     Node* bol = cmp->fast_out(i);
1528     for (DUIterator_Fast i2max, i2 = bol->fast_outs(i2max); i2 < i2max; i2++) {
1529       Node* iff = bol->fast_out(i2);
1530       if (iff->is_CountedLoopEnd()) {
1531         CountedLoopEndNode* cle = iff->as_CountedLoopEnd();
1532         if (cle->limit() == n) {
1533           PhiNode* phi = cle->phi();
1534           if (phi != NULL) {
1535             return phi;
1536           }
1537         }
1538       }
1539     }
1540   }
1541   return NULL;
1542 }
1543 
1544 void PhaseIterGVN::add_users_to_worklist( Node *n ) {
1545   add_users_to_worklist0(n);
1546 
1547   // Move users of node to worklist
1548   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1549     Node* use = n->fast_out(i); // Get use
1550 
1551     if( use->is_Multi() ||      // Multi-definer?  Push projs on worklist
1552         use->is_Store() )       // Enable store/load same address
1553       add_users_to_worklist0(use);
1554 
1555     // If we changed the receiver type to a call, we need to revisit
1556     // the Catch following the call.  It's looking for a non-NULL
1557     // receiver to know when to enable the regular fall-through path
1558     // in addition to the NullPtrException path.
1559     if (use->is_CallDynamicJava() && n == use->in(TypeFunc::Parms)) {
1560       Node* p = use->as_CallDynamicJava()->proj_out_or_null(TypeFunc::Control);
1561       if (p != NULL) {
1562         add_users_to_worklist0(p);
1563       }
1564     }
1565 
1566     uint use_op = use->Opcode();
1567     if(use->is_Cmp()) {       // Enable CMP/BOOL optimization
1568       add_users_to_worklist(use); // Put Bool on worklist
1569       if (use->outcnt() > 0) {
1570         Node* bol = use->raw_out(0);
1571         if (bol->outcnt() > 0) {
1572           Node* iff = bol->raw_out(0);
1573           if (iff->outcnt() == 2) {
1574             // Look for the 'is_x2logic' pattern: "x ? : 0 : 1" and put the
1575             // phi merging either 0 or 1 onto the worklist
1576             Node* ifproj0 = iff->raw_out(0);
1577             Node* ifproj1 = iff->raw_out(1);
1578             if (ifproj0->outcnt() > 0 && ifproj1->outcnt() > 0) {
1579               Node* region0 = ifproj0->raw_out(0);
1580               Node* region1 = ifproj1->raw_out(0);
1581               if( region0 == region1 )
1582                 add_users_to_worklist0(region0);
1583             }
1584           }
1585         }
1586       }
1587       if (use_op == Op_CmpI) {
1588         Node* phi = countedloop_phi_from_cmp((CmpINode*)use, n);
1589         if (phi != NULL) {
1590           // If an opaque node feeds into the limit condition of a
1591           // CountedLoop, we need to process the Phi node for the
1592           // induction variable when the opaque node is removed:
1593           // the range of values taken by the Phi is now known and
1594           // so its type is also known.
1595           _worklist.push(phi);
1596         }
1597         Node* in1 = use->in(1);
1598         for (uint i = 0; i < in1->outcnt(); i++) {
1599           if (in1->raw_out(i)->Opcode() == Op_CastII) {
1600             Node* castii = in1->raw_out(i);
1601             if (castii->in(0) != NULL && castii->in(0)->in(0) != NULL && castii->in(0)->in(0)->is_If()) {
1602               Node* ifnode = castii->in(0)->in(0);
1603               if (ifnode->in(1) != NULL && ifnode->in(1)->is_Bool() && ifnode->in(1)->in(1) == use) {
1604                 // Reprocess a CastII node that may depend on an
1605                 // opaque node value when the opaque node is
1606                 // removed. In case it carries a dependency we can do
1607                 // a better job of computing its type.
1608                 _worklist.push(castii);
1609               }
1610             }
1611           }
1612         }
1613       }
1614     }
1615 
1616     // If changed Cast input, check Phi users for simple cycles
1617     if (use->is_ConstraintCast()) {
1618       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1619         Node* u = use->fast_out(i2);
1620         if (u->is_Phi())
1621           _worklist.push(u);
1622       }
1623     }
1624     // If changed LShift inputs, check RShift users for useless sign-ext
1625     if( use_op == Op_LShiftI ) {
1626       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1627         Node* u = use->fast_out(i2);
1628         if (u->Opcode() == Op_RShiftI)
1629           _worklist.push(u);
1630       }
1631     }
1632     // If changed AddI/SubI inputs, check CmpU for range check optimization.
1633     if (use_op == Op_AddI || use_op == Op_SubI) {
1634       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1635         Node* u = use->fast_out(i2);
1636         if (u->is_Cmp() && (u->Opcode() == Op_CmpU)) {
1637           _worklist.push(u);
1638         }
1639       }
1640     }
1641     // If changed AddP inputs, check Stores for loop invariant
1642     if( use_op == Op_AddP ) {
1643       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1644         Node* u = use->fast_out(i2);
1645         if (u->is_Mem())
1646           _worklist.push(u);
1647       }
1648     }
1649     // If changed initialization activity, check dependent Stores
1650     if (use_op == Op_Allocate || use_op == Op_AllocateArray) {
1651       InitializeNode* init = use->as_Allocate()->initialization();
1652       if (init != NULL) {
1653         Node* imem = init->proj_out_or_null(TypeFunc::Memory);
1654         if (imem != NULL)  add_users_to_worklist0(imem);
1655       }
1656     }
1657     if (use_op == Op_Initialize) {
1658       Node* imem = use->as_Initialize()->proj_out_or_null(TypeFunc::Memory);
1659       if (imem != NULL)  add_users_to_worklist0(imem);
1660     }
1661     if (use_op == Op_CastP2X) {
1662       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1663         Node* u = use->fast_out(i2);
1664         if (u->Opcode() == Op_AndX) {
1665           _worklist.push(u);
1666         }
1667       }
1668     }
1669     // Loading the java mirror from a Klass requires two loads and the type
1670     // of the mirror load depends on the type of 'n'. See LoadNode::Value().
1671     //   LoadBarrier?(LoadP(LoadP(AddP(foo:Klass, #java_mirror))))
1672     BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1673     bool has_load_barriers = bs->has_load_barriers();
1674 
1675     if (use_op == Op_LoadP && use->bottom_type()->isa_rawptr()) {
1676       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1677         Node* u = use->fast_out(i2);
1678         const Type* ut = u->bottom_type();
1679         if (u->Opcode() == Op_LoadP && ut->isa_instptr()) {
1680           if (has_load_barriers) {
1681             // Search for load barriers behind the load
1682             for (DUIterator_Fast i3max, i3 = u->fast_outs(i3max); i3 < i3max; i3++) {
1683               Node* b = u->fast_out(i3);
1684               if (bs->is_gc_barrier_node(b)) {
1685                 _worklist.push(b);
1686               }
1687             }
1688           }
1689           _worklist.push(u);
1690         }
1691       }
1692     }
1693 
1694     BarrierSet::barrier_set()->barrier_set_c2()->igvn_add_users_to_worklist(this, use);
1695   }
1696 }
1697 
1698 /**
1699  * Remove the speculative part of all types that we know of
1700  */
1701 void PhaseIterGVN::remove_speculative_types()  {
1702   assert(UseTypeSpeculation, "speculation is off");
1703   for (uint i = 0; i < _types.Size(); i++)  {
1704     const Type* t = _types.fast_lookup(i);
1705     if (t != NULL) {
1706       _types.map(i, t->remove_speculative());
1707     }
1708   }
1709   _table.check_no_speculative_types();
1710 }
1711 
1712 //=============================================================================
1713 #ifndef PRODUCT
1714 uint PhaseCCP::_total_invokes   = 0;
1715 uint PhaseCCP::_total_constants = 0;
1716 #endif
1717 //------------------------------PhaseCCP---------------------------------------
1718 // Conditional Constant Propagation, ala Wegman & Zadeck
1719 PhaseCCP::PhaseCCP( PhaseIterGVN *igvn ) : PhaseIterGVN(igvn) {
1720   NOT_PRODUCT( clear_constants(); )
1721   assert( _worklist.size() == 0, "" );
1722   // Clear out _nodes from IterGVN.  Must be clear to transform call.
1723   _nodes.clear();               // Clear out from IterGVN
1724   analyze();
1725 }
1726 
1727 #ifndef PRODUCT
1728 //------------------------------~PhaseCCP--------------------------------------
1729 PhaseCCP::~PhaseCCP() {
1730   inc_invokes();
1731   _total_constants += count_constants();
1732 }
1733 #endif
1734 
1735 
1736 #ifdef ASSERT
1737 static bool ccp_type_widens(const Type* t, const Type* t0) {
1738   assert(t->meet(t0) == t, "Not monotonic");
1739   switch (t->base() == t0->base() ? t->base() : Type::Top) {
1740   case Type::Int:
1741     assert(t0->isa_int()->_widen <= t->isa_int()->_widen, "widen increases");
1742     break;
1743   case Type::Long:
1744     assert(t0->isa_long()->_widen <= t->isa_long()->_widen, "widen increases");
1745     break;
1746   default:
1747     break;
1748   }
1749   return true;
1750 }
1751 #endif //ASSERT
1752 
1753 //------------------------------analyze----------------------------------------
1754 void PhaseCCP::analyze() {
1755   // Initialize all types to TOP, optimistic analysis
1756   for (int i = C->unique() - 1; i >= 0; i--)  {
1757     _types.map(i,Type::TOP);
1758   }
1759 
1760   // Push root onto worklist
1761   Unique_Node_List worklist;
1762   worklist.push(C->root());
1763 
1764   // Pull from worklist; compute new value; push changes out.
1765   // This loop is the meat of CCP.
1766   while( worklist.size() ) {
1767     Node *n = worklist.pop();
1768     const Type *t = n->Value(this);
1769     if (t != type(n)) {
1770       assert(ccp_type_widens(t, type(n)), "ccp type must widen");
1771 #ifndef PRODUCT
1772       if( TracePhaseCCP ) {
1773         t->dump();
1774         do { tty->print("\t"); } while (tty->position() < 16);
1775         n->dump();
1776       }
1777 #endif
1778       set_type(n, t);
1779       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1780         Node* m = n->fast_out(i);   // Get user
1781         if (m->is_Region()) {  // New path to Region?  Must recheck Phis too
1782           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1783             Node* p = m->fast_out(i2); // Propagate changes to uses
1784             if (p->bottom_type() != type(p)) { // If not already bottomed out
1785               worklist.push(p); // Propagate change to user
1786             }
1787           }
1788         }
1789         // If we changed the receiver type to a call, we need to revisit
1790         // the Catch following the call.  It's looking for a non-NULL
1791         // receiver to know when to enable the regular fall-through path
1792         // in addition to the NullPtrException path
1793         if (m->is_Call()) {
1794           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1795             Node* p = m->fast_out(i2);  // Propagate changes to uses
1796             if (p->is_Proj() && p->as_Proj()->_con == TypeFunc::Control && p->outcnt() == 1) {
1797               worklist.push(p->unique_out());
1798             }
1799           }
1800         }
1801         if (m->bottom_type() != type(m)) { // If not already bottomed out
1802           worklist.push(m);     // Propagate change to user
1803         }
1804 
1805         // CmpU nodes can get their type information from two nodes up in the
1806         // graph (instead of from the nodes immediately above). Make sure they
1807         // are added to the worklist if nodes they depend on are updated, since
1808         // they could be missed and get wrong types otherwise.
1809         uint m_op = m->Opcode();
1810         if (m_op == Op_AddI || m_op == Op_SubI) {
1811           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1812             Node* p = m->fast_out(i2); // Propagate changes to uses
1813             if (p->Opcode() == Op_CmpU) {
1814               // Got a CmpU which might need the new type information from node n.
1815               if(p->bottom_type() != type(p)) { // If not already bottomed out
1816                 worklist.push(p); // Propagate change to user
1817               }
1818             }
1819           }
1820         }
1821         // If n is used in a counted loop exit condition then the type
1822         // of the counted loop's Phi depends on the type of n. See
1823         // PhiNode::Value().
1824         if (m_op == Op_CmpI) {
1825           PhiNode* phi = countedloop_phi_from_cmp((CmpINode*)m, n);
1826           if (phi != NULL) {
1827             worklist.push(phi);
1828           }
1829         }
1830         if (m_op == Op_CastP2X) {
1831           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1832             Node* u = m->fast_out(i2);
1833             if (u->Opcode() == Op_AndX) {
1834               worklist.push(u);
1835             }
1836           }
1837         }
1838         // Loading the java mirror from a Klass requires two loads and the type
1839         // of the mirror load depends on the type of 'n'. See LoadNode::Value().
1840         BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1841         bool has_load_barriers = bs->has_load_barriers();
1842 
1843         if (m_op == Op_LoadP && m->bottom_type()->isa_rawptr()) {
1844           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1845             Node* u = m->fast_out(i2);
1846             const Type* ut = u->bottom_type();
1847             if (u->Opcode() == Op_LoadP && ut->isa_instptr() && ut != type(u)) {
1848               if (has_load_barriers) {
1849                 // Search for load barriers behind the load
1850                 for (DUIterator_Fast i3max, i3 = u->fast_outs(i3max); i3 < i3max; i3++) {
1851                   Node* b = u->fast_out(i3);
1852                   if (bs->is_gc_barrier_node(b)) {
1853                     worklist.push(b);
1854                   }
1855                 }
1856               }
1857               worklist.push(u);
1858             }
1859           }
1860         }
1861 
1862         BarrierSet::barrier_set()->barrier_set_c2()->ccp_analyze(this, worklist, m);
1863       }
1864     }
1865   }
1866 }
1867 
1868 //------------------------------do_transform-----------------------------------
1869 // Top level driver for the recursive transformer
1870 void PhaseCCP::do_transform() {
1871   // Correct leaves of new-space Nodes; they point to old-space.
1872   C->set_root( transform(C->root())->as_Root() );
1873   assert( C->top(),  "missing TOP node" );
1874   assert( C->root(), "missing root" );
1875 }
1876 
1877 //------------------------------transform--------------------------------------
1878 // Given a Node in old-space, clone him into new-space.
1879 // Convert any of his old-space children into new-space children.
1880 Node *PhaseCCP::transform( Node *n ) {
1881   Node *new_node = _nodes[n->_idx]; // Check for transformed node
1882   if( new_node != NULL )
1883     return new_node;                // Been there, done that, return old answer
1884   new_node = transform_once(n);     // Check for constant
1885   _nodes.map( n->_idx, new_node );  // Flag as having been cloned
1886 
1887   // Allocate stack of size _nodes.Size()/2 to avoid frequent realloc
1888   GrowableArray <Node *> trstack(C->live_nodes() >> 1);
1889 
1890   trstack.push(new_node);           // Process children of cloned node
1891   while ( trstack.is_nonempty() ) {
1892     Node *clone = trstack.pop();
1893     uint cnt = clone->req();
1894     for( uint i = 0; i < cnt; i++ ) {          // For all inputs do
1895       Node *input = clone->in(i);
1896       if( input != NULL ) {                    // Ignore NULLs
1897         Node *new_input = _nodes[input->_idx]; // Check for cloned input node
1898         if( new_input == NULL ) {
1899           new_input = transform_once(input);   // Check for constant
1900           _nodes.map( input->_idx, new_input );// Flag as having been cloned
1901           trstack.push(new_input);
1902         }
1903         assert( new_input == clone->in(i), "insanity check");
1904       }
1905     }
1906   }
1907   return new_node;
1908 }
1909 
1910 
1911 //------------------------------transform_once---------------------------------
1912 // For PhaseCCP, transformation is IDENTITY unless Node computed a constant.
1913 Node *PhaseCCP::transform_once( Node *n ) {
1914   const Type *t = type(n);
1915   // Constant?  Use constant Node instead
1916   if( t->singleton() ) {
1917     Node *nn = n;               // Default is to return the original constant
1918     if( t == Type::TOP ) {
1919       // cache my top node on the Compile instance
1920       if( C->cached_top_node() == NULL || C->cached_top_node()->in(0) == NULL ) {
1921         C->set_cached_top_node(ConNode::make(Type::TOP));
1922         set_type(C->top(), Type::TOP);
1923       }
1924       nn = C->top();
1925     }
1926     if( !n->is_Con() ) {
1927       if( t != Type::TOP ) {
1928         nn = makecon(t);        // ConNode::make(t);
1929         NOT_PRODUCT( inc_constants(); )
1930       } else if( n->is_Region() ) { // Unreachable region
1931         // Note: nn == C->top()
1932         n->set_req(0, NULL);        // Cut selfreference
1933         bool progress = true;
1934         uint max = n->outcnt();
1935         DUIterator i;
1936         while (progress) {
1937           progress = false;
1938           // Eagerly remove dead phis to avoid phis copies creation.
1939           for (i = n->outs(); n->has_out(i); i++) {
1940             Node* m = n->out(i);
1941             if (m->is_Phi()) {
1942               assert(type(m) == Type::TOP, "Unreachable region should not have live phis.");
1943               replace_node(m, nn);
1944               if (max != n->outcnt()) {
1945                 progress = true;
1946                 i = n->refresh_out_pos(i);
1947                 max = n->outcnt();
1948               }
1949             }
1950           }
1951         }
1952       }
1953       replace_node(n,nn);       // Update DefUse edges for new constant
1954     }
1955     return nn;
1956   }
1957 
1958   // If x is a TypeNode, capture any more-precise type permanently into Node
1959   if (t != n->bottom_type()) {
1960     hash_delete(n);             // changing bottom type may force a rehash
1961     n->raise_bottom_type(t);
1962     _worklist.push(n);          // n re-enters the hash table via the worklist
1963   }
1964 
1965   // TEMPORARY fix to ensure that 2nd GVN pass eliminates NULL checks
1966   switch( n->Opcode() ) {
1967   case Op_FastLock:      // Revisit FastLocks for lock coarsening
1968   case Op_If:
1969   case Op_CountedLoopEnd:
1970   case Op_Region:
1971   case Op_Loop:
1972   case Op_CountedLoop:
1973   case Op_Conv2B:
1974   case Op_Opaque1:
1975   case Op_Opaque2:
1976     _worklist.push(n);
1977     break;
1978   default:
1979     break;
1980   }
1981 
1982   return  n;
1983 }
1984 
1985 //---------------------------------saturate------------------------------------
1986 const Type* PhaseCCP::saturate(const Type* new_type, const Type* old_type,
1987                                const Type* limit_type) const {
1988   const Type* wide_type = new_type->widen(old_type, limit_type);
1989   if (wide_type != new_type) {          // did we widen?
1990     // If so, we may have widened beyond the limit type.  Clip it back down.
1991     new_type = wide_type->filter(limit_type);
1992   }
1993   return new_type;
1994 }
1995 
1996 //------------------------------print_statistics-------------------------------
1997 #ifndef PRODUCT
1998 void PhaseCCP::print_statistics() {
1999   tty->print_cr("CCP: %d  constants found: %d", _total_invokes, _total_constants);
2000 }
2001 #endif
2002 
2003 
2004 //=============================================================================
2005 #ifndef PRODUCT
2006 uint PhasePeephole::_total_peepholes = 0;
2007 #endif
2008 //------------------------------PhasePeephole----------------------------------
2009 // Conditional Constant Propagation, ala Wegman & Zadeck
2010 PhasePeephole::PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg )
2011   : PhaseTransform(Peephole), _regalloc(regalloc), _cfg(cfg) {
2012   NOT_PRODUCT( clear_peepholes(); )
2013 }
2014 
2015 #ifndef PRODUCT
2016 //------------------------------~PhasePeephole---------------------------------
2017 PhasePeephole::~PhasePeephole() {
2018   _total_peepholes += count_peepholes();
2019 }
2020 #endif
2021 
2022 //------------------------------transform--------------------------------------
2023 Node *PhasePeephole::transform( Node *n ) {
2024   ShouldNotCallThis();
2025   return NULL;
2026 }
2027 
2028 //------------------------------do_transform-----------------------------------
2029 void PhasePeephole::do_transform() {
2030   bool method_name_not_printed = true;
2031 
2032   // Examine each basic block
2033   for (uint block_number = 1; block_number < _cfg.number_of_blocks(); ++block_number) {
2034     Block* block = _cfg.get_block(block_number);
2035     bool block_not_printed = true;
2036 
2037     // and each instruction within a block
2038     uint end_index = block->number_of_nodes();
2039     // block->end_idx() not valid after PhaseRegAlloc
2040     for( uint instruction_index = 1; instruction_index < end_index; ++instruction_index ) {
2041       Node     *n = block->get_node(instruction_index);
2042       if( n->is_Mach() ) {
2043         MachNode *m = n->as_Mach();
2044         int deleted_count = 0;
2045         // check for peephole opportunities
2046         MachNode *m2 = m->peephole(block, instruction_index, _regalloc, deleted_count);
2047         if( m2 != NULL ) {
2048 #ifndef PRODUCT
2049           if( PrintOptoPeephole ) {
2050             // Print method, first time only
2051             if( C->method() && method_name_not_printed ) {
2052               C->method()->print_short_name(); tty->cr();
2053               method_name_not_printed = false;
2054             }
2055             // Print this block
2056             if( Verbose && block_not_printed) {
2057               tty->print_cr("in block");
2058               block->dump();
2059               block_not_printed = false;
2060             }
2061             // Print instructions being deleted
2062             for( int i = (deleted_count - 1); i >= 0; --i ) {
2063               block->get_node(instruction_index-i)->as_Mach()->format(_regalloc); tty->cr();
2064             }
2065             tty->print_cr("replaced with");
2066             // Print new instruction
2067             m2->format(_regalloc);
2068             tty->print("\n\n");
2069           }
2070 #endif
2071           // Remove old nodes from basic block and update instruction_index
2072           // (old nodes still exist and may have edges pointing to them
2073           //  as register allocation info is stored in the allocator using
2074           //  the node index to live range mappings.)
2075           uint safe_instruction_index = (instruction_index - deleted_count);
2076           for( ; (instruction_index > safe_instruction_index); --instruction_index ) {
2077             block->remove_node( instruction_index );
2078           }
2079           // install new node after safe_instruction_index
2080           block->insert_node(m2, safe_instruction_index + 1);
2081           end_index = block->number_of_nodes() - 1; // Recompute new block size
2082           NOT_PRODUCT( inc_peepholes(); )
2083         }
2084       }
2085     }
2086   }
2087 }
2088 
2089 //------------------------------print_statistics-------------------------------
2090 #ifndef PRODUCT
2091 void PhasePeephole::print_statistics() {
2092   tty->print_cr("Peephole: peephole rules applied: %d",  _total_peepholes);
2093 }
2094 #endif
2095 
2096 
2097 //=============================================================================
2098 //------------------------------set_req_X--------------------------------------
2099 void Node::set_req_X( uint i, Node *n, PhaseIterGVN *igvn ) {
2100   assert( is_not_dead(n), "can not use dead node");
2101   assert( igvn->hash_find(this) != this, "Need to remove from hash before changing edges" );
2102   Node *old = in(i);
2103   set_req(i, n);
2104 
2105   // old goes dead?
2106   if( old ) {
2107     switch (old->outcnt()) {
2108     case 0:
2109       // Put into the worklist to kill later. We do not kill it now because the
2110       // recursive kill will delete the current node (this) if dead-loop exists
2111       if (!old->is_top())
2112         igvn->_worklist.push( old );
2113       break;
2114     case 1:
2115       if( old->is_Store() || old->has_special_unique_user() )
2116         igvn->add_users_to_worklist( old );
2117       break;
2118     case 2:
2119       if( old->is_Store() )
2120         igvn->add_users_to_worklist( old );
2121       if( old->Opcode() == Op_Region )
2122         igvn->_worklist.push(old);
2123       break;
2124     case 3:
2125       if( old->Opcode() == Op_Region ) {
2126         igvn->_worklist.push(old);
2127         igvn->add_users_to_worklist( old );
2128       }
2129       break;
2130     default:
2131       break;
2132     }
2133 
2134     BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, old);
2135   }
2136 
2137 }
2138 
2139 //-------------------------------replace_by-----------------------------------
2140 // Using def-use info, replace one node for another.  Follow the def-use info
2141 // to all users of the OLD node.  Then make all uses point to the NEW node.
2142 void Node::replace_by(Node *new_node) {
2143   assert(!is_top(), "top node has no DU info");
2144   for (DUIterator_Last imin, i = last_outs(imin); i >= imin; ) {
2145     Node* use = last_out(i);
2146     uint uses_found = 0;
2147     for (uint j = 0; j < use->len(); j++) {
2148       if (use->in(j) == this) {
2149         if (j < use->req())
2150               use->set_req(j, new_node);
2151         else  use->set_prec(j, new_node);
2152         uses_found++;
2153       }
2154     }
2155     i -= uses_found;    // we deleted 1 or more copies of this edge
2156   }
2157 }
2158 
2159 //=============================================================================
2160 //-----------------------------------------------------------------------------
2161 void Type_Array::grow( uint i ) {
2162   if( !_max ) {
2163     _max = 1;
2164     _types = (const Type**)_a->Amalloc( _max * sizeof(Type*) );
2165     _types[0] = NULL;
2166   }
2167   uint old = _max;
2168   while( i >= _max ) _max <<= 1;        // Double to fit
2169   _types = (const Type**)_a->Arealloc( _types, old*sizeof(Type*),_max*sizeof(Type*));
2170   memset( &_types[old], 0, (_max-old)*sizeof(Type*) );
2171 }
2172 
2173 //------------------------------dump-------------------------------------------
2174 #ifndef PRODUCT
2175 void Type_Array::dump() const {
2176   uint max = Size();
2177   for( uint i = 0; i < max; i++ ) {
2178     if( _types[i] != NULL ) {
2179       tty->print("  %d\t== ", i); _types[i]->dump(); tty->cr();
2180     }
2181   }
2182 }
2183 #endif