1 /*
   2  * Copyright (c) 1997, 2012, 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 "memory/allocation.inline.hpp"
  27 #include "opto/block.hpp"
  28 #include "opto/callnode.hpp"
  29 #include "opto/cfgnode.hpp"
  30 #include "opto/connode.hpp"
  31 #include "opto/idealGraphPrinter.hpp"
  32 #include "opto/loopnode.hpp"
  33 #include "opto/machnode.hpp"
  34 #include "opto/opcodes.hpp"
  35 #include "opto/phaseX.hpp"
  36 #include "opto/regalloc.hpp"
  37 #include "opto/rootnode.hpp"
  38 
  39 //=============================================================================
  40 #define NODE_HASH_MINIMUM_SIZE    255
  41 //------------------------------NodeHash---------------------------------------
  42 NodeHash::NodeHash(uint est_max_size) :
  43   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
  44   _a(Thread::current()->resource_area()),
  45   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) ), // (Node**)_a->Amalloc(_max * sizeof(Node*)) ),
  46   _inserts(0), _insert_limit( insert_limit() ),
  47   _look_probes(0), _lookup_hits(0), _lookup_misses(0),
  48   _total_insert_probes(0), _total_inserts(0),
  49   _insert_probes(0), _grows(0) {
  50   // _sentinel must be in the current node space
  51   _sentinel = new (Compile::current()) ProjNode(NULL, TypeFunc::Control);
  52   memset(_table,0,sizeof(Node*)*_max);
  53 }
  54 
  55 //------------------------------NodeHash---------------------------------------
  56 NodeHash::NodeHash(Arena *arena, uint est_max_size) :
  57   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
  58   _a(arena),
  59   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) ),
  60   _inserts(0), _insert_limit( insert_limit() ),
  61   _look_probes(0), _lookup_hits(0), _lookup_misses(0),
  62   _delete_probes(0), _delete_hits(0), _delete_misses(0),
  63   _total_insert_probes(0), _total_inserts(0),
  64   _insert_probes(0), _grows(0) {
  65   // _sentinel must be in the current node space
  66   _sentinel = new (Compile::current()) ProjNode(NULL, TypeFunc::Control);
  67   memset(_table,0,sizeof(Node*)*_max);
  68 }
  69 
  70 //------------------------------NodeHash---------------------------------------
  71 NodeHash::NodeHash(NodeHash *nh) {
  72   debug_only(_table = (Node**)badAddress);   // interact correctly w/ operator=
  73   // just copy in all the fields
  74   *this = *nh;
  75   // nh->_sentinel must be in the current node space
  76 }
  77 
  78 void NodeHash::replace_with(NodeHash *nh) {
  79   debug_only(_table = (Node**)badAddress);   // interact correctly w/ operator=
  80   // just copy in all the fields
  81   *this = *nh;
  82   // nh->_sentinel must be in the current node space
  83 }
  84 
  85 //------------------------------hash_find--------------------------------------
  86 // Find in hash table
  87 Node *NodeHash::hash_find( const Node *n ) {
  88   // ((Node*)n)->set_hash( n->hash() );
  89   uint hash = n->hash();
  90   if (hash == Node::NO_HASH) {
  91     debug_only( _lookup_misses++ );
  92     return NULL;
  93   }
  94   uint key = hash & (_max-1);
  95   uint stride = key | 0x01;
  96   debug_only( _look_probes++ );
  97   Node *k = _table[key];        // Get hashed value
  98   if( !k ) {                    // ?Miss?
  99     debug_only( _lookup_misses++ );
 100     return NULL;                // Miss!
 101   }
 102 
 103   int op = n->Opcode();
 104   uint req = n->req();
 105   while( 1 ) {                  // While probing hash table
 106     if( k->req() == req &&      // Same count of inputs
 107         k->Opcode() == op ) {   // Same Opcode
 108       for( uint i=0; i<req; i++ )
 109         if( n->in(i)!=k->in(i)) // Different inputs?
 110           goto collision;       // "goto" is a speed hack...
 111       if( n->cmp(*k) ) {        // Check for any special bits
 112         debug_only( _lookup_hits++ );
 113         return k;               // Hit!
 114       }
 115     }
 116   collision:
 117     debug_only( _look_probes++ );
 118     key = (key + stride/*7*/) & (_max-1); // Stride through table with relative prime
 119     k = _table[key];            // Get hashed value
 120     if( !k ) {                  // ?Miss?
 121       debug_only( _lookup_misses++ );
 122       return NULL;              // Miss!
 123     }
 124   }
 125   ShouldNotReachHere();
 126   return NULL;
 127 }
 128 
 129 //------------------------------hash_find_insert-------------------------------
 130 // Find in hash table, insert if not already present
 131 // Used to preserve unique entries in hash table
 132 Node *NodeHash::hash_find_insert( Node *n ) {
 133   // n->set_hash( );
 134   uint hash = n->hash();
 135   if (hash == Node::NO_HASH) {
 136     debug_only( _lookup_misses++ );
 137     return NULL;
 138   }
 139   uint key = hash & (_max-1);
 140   uint stride = key | 0x01;     // stride must be relatively prime to table siz
 141   uint first_sentinel = 0;      // replace a sentinel if seen.
 142   debug_only( _look_probes++ );
 143   Node *k = _table[key];        // Get hashed value
 144   if( !k ) {                    // ?Miss?
 145     debug_only( _lookup_misses++ );
 146     _table[key] = n;            // Insert into table!
 147     debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 148     check_grow();               // Grow table if insert hit limit
 149     return NULL;                // Miss!
 150   }
 151   else if( k == _sentinel ) {
 152     first_sentinel = key;      // Can insert here
 153   }
 154 
 155   int op = n->Opcode();
 156   uint req = n->req();
 157   while( 1 ) {                  // While probing hash table
 158     if( k->req() == req &&      // Same count of inputs
 159         k->Opcode() == op ) {   // Same Opcode
 160       for( uint i=0; i<req; i++ )
 161         if( n->in(i)!=k->in(i)) // Different inputs?
 162           goto collision;       // "goto" is a speed hack...
 163       if( n->cmp(*k) ) {        // Check for any special bits
 164         debug_only( _lookup_hits++ );
 165         return k;               // Hit!
 166       }
 167     }
 168   collision:
 169     debug_only( _look_probes++ );
 170     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
 171     k = _table[key];            // Get hashed value
 172     if( !k ) {                  // ?Miss?
 173       debug_only( _lookup_misses++ );
 174       key = (first_sentinel == 0) ? key : first_sentinel; // ?saw sentinel?
 175       _table[key] = n;          // Insert into table!
 176       debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 177       check_grow();             // Grow table if insert hit limit
 178       return NULL;              // Miss!
 179     }
 180     else if( first_sentinel == 0 && k == _sentinel ) {
 181       first_sentinel = key;    // Can insert here
 182     }
 183 
 184   }
 185   ShouldNotReachHere();
 186   return NULL;
 187 }
 188 
 189 //------------------------------hash_insert------------------------------------
 190 // Insert into hash table
 191 void NodeHash::hash_insert( Node *n ) {
 192   // // "conflict" comments -- print nodes that conflict
 193   // bool conflict = false;
 194   // n->set_hash();
 195   uint hash = n->hash();
 196   if (hash == Node::NO_HASH) {
 197     return;
 198   }
 199   check_grow();
 200   uint key = hash & (_max-1);
 201   uint stride = key | 0x01;
 202 
 203   while( 1 ) {                  // While probing hash table
 204     debug_only( _insert_probes++ );
 205     Node *k = _table[key];      // Get hashed value
 206     if( !k || (k == _sentinel) ) break;       // Found a slot
 207     assert( k != n, "already inserted" );
 208     // if( PrintCompilation && PrintOptoStatistics && Verbose ) { tty->print("  conflict: "); k->dump(); conflict = true; }
 209     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
 210   }
 211   _table[key] = n;              // Insert into table!
 212   debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 213   // if( conflict ) { n->dump(); }
 214 }
 215 
 216 //------------------------------hash_delete------------------------------------
 217 // Replace in hash table with sentinel
 218 bool NodeHash::hash_delete( const Node *n ) {
 219   Node *k;
 220   uint hash = n->hash();
 221   if (hash == Node::NO_HASH) {
 222     debug_only( _delete_misses++ );
 223     return false;
 224   }
 225   uint key = hash & (_max-1);
 226   uint stride = key | 0x01;
 227   debug_only( uint counter = 0; );
 228   for( ; /* (k != NULL) && (k != _sentinel) */; ) {
 229     debug_only( counter++ );
 230     debug_only( _delete_probes++ );
 231     k = _table[key];            // Get hashed value
 232     if( !k ) {                  // Miss?
 233       debug_only( _delete_misses++ );
 234 #ifdef ASSERT
 235       if( VerifyOpto ) {
 236         for( uint i=0; i < _max; i++ )
 237           assert( _table[i] != n, "changed edges with rehashing" );
 238       }
 239 #endif
 240       return false;             // Miss! Not in chain
 241     }
 242     else if( n == k ) {
 243       debug_only( _delete_hits++ );
 244       _table[key] = _sentinel;  // Hit! Label as deleted entry
 245       debug_only(((Node*)n)->exit_hash_lock()); // Unlock the node upon removal from table.
 246       return true;
 247     }
 248     else {
 249       // collision: move through table with prime offset
 250       key = (key + stride/*7*/) & (_max-1);
 251       assert( counter <= _insert_limit, "Cycle in hash-table");
 252     }
 253   }
 254   ShouldNotReachHere();
 255   return false;
 256 }
 257 
 258 //------------------------------round_up---------------------------------------
 259 // Round up to nearest power of 2
 260 uint NodeHash::round_up( uint x ) {
 261   x += (x>>2);                  // Add 25% slop
 262   if( x <16 ) return 16;        // Small stuff
 263   uint i=16;
 264   while( i < x ) i <<= 1;       // Double to fit
 265   return i;                     // Return hash table size
 266 }
 267 
 268 //------------------------------grow-------------------------------------------
 269 // Grow _table to next power of 2 and insert old entries
 270 void  NodeHash::grow() {
 271   // Record old state
 272   uint   old_max   = _max;
 273   Node **old_table = _table;
 274   // Construct new table with twice the space
 275   _grows++;
 276   _total_inserts       += _inserts;
 277   _total_insert_probes += _insert_probes;
 278   _inserts         = 0;
 279   _insert_probes   = 0;
 280   _max     = _max << 1;
 281   _table   = NEW_ARENA_ARRAY( _a , Node* , _max ); // (Node**)_a->Amalloc( _max * sizeof(Node*) );
 282   memset(_table,0,sizeof(Node*)*_max);
 283   _insert_limit = insert_limit();
 284   // Insert old entries into the new table
 285   for( uint i = 0; i < old_max; i++ ) {
 286     Node *m = *old_table++;
 287     if( !m || m == _sentinel ) continue;
 288     debug_only(m->exit_hash_lock()); // Unlock the node upon removal from old table.
 289     hash_insert(m);
 290   }
 291 }
 292 
 293 //------------------------------clear------------------------------------------
 294 // Clear all entries in _table to NULL but keep storage
 295 void  NodeHash::clear() {
 296 #ifdef ASSERT
 297   // Unlock all nodes upon removal from table.
 298   for (uint i = 0; i < _max; i++) {
 299     Node* n = _table[i];
 300     if (!n || n == _sentinel)  continue;
 301     n->exit_hash_lock();
 302   }
 303 #endif
 304 
 305   memset( _table, 0, _max * sizeof(Node*) );
 306 }
 307 
 308 //-----------------------remove_useless_nodes----------------------------------
 309 // Remove useless nodes from value table,
 310 // implementation does not depend on hash function
 311 void NodeHash::remove_useless_nodes(VectorSet &useful) {
 312 
 313   // Dead nodes in the hash table inherited from GVN should not replace
 314   // existing nodes, remove dead nodes.
 315   uint max = size();
 316   Node *sentinel_node = sentinel();
 317   for( uint i = 0; i < max; ++i ) {
 318     Node *n = at(i);
 319     if(n != NULL && n != sentinel_node && !useful.test(n->_idx)) {
 320       debug_only(n->exit_hash_lock()); // Unlock the node when removed
 321       _table[i] = sentinel_node;       // Replace with placeholder
 322     }
 323   }
 324 }
 325 
 326 #ifndef PRODUCT
 327 //------------------------------dump-------------------------------------------
 328 // Dump statistics for the hash table
 329 void NodeHash::dump() {
 330   _total_inserts       += _inserts;
 331   _total_insert_probes += _insert_probes;
 332   if (PrintCompilation && PrintOptoStatistics && Verbose && (_inserts > 0)) {
 333     if (WizardMode) {
 334       for (uint i=0; i<_max; i++) {
 335         if (_table[i])
 336           tty->print("%d/%d/%d ",i,_table[i]->hash()&(_max-1),_table[i]->_idx);
 337       }
 338     }
 339     tty->print("\nGVN Hash stats:  %d grows to %d max_size\n", _grows, _max);
 340     tty->print("  %d/%d (%8.1f%% full)\n", _inserts, _max, (double)_inserts/_max*100.0);
 341     tty->print("  %dp/(%dh+%dm) (%8.2f probes/lookup)\n", _look_probes, _lookup_hits, _lookup_misses, (double)_look_probes/(_lookup_hits+_lookup_misses));
 342     tty->print("  %dp/%di (%8.2f probes/insert)\n", _total_insert_probes, _total_inserts, (double)_total_insert_probes/_total_inserts);
 343     // sentinels increase lookup cost, but not insert cost
 344     assert((_lookup_misses+_lookup_hits)*4+100 >= _look_probes, "bad hash function");
 345     assert( _inserts+(_inserts>>3) < _max, "table too full" );
 346     assert( _inserts*3+100 >= _insert_probes, "bad hash function" );
 347   }
 348 }
 349 
 350 Node *NodeHash::find_index(uint idx) { // For debugging
 351   // Find an entry by its index value
 352   for( uint i = 0; i < _max; i++ ) {
 353     Node *m = _table[i];
 354     if( !m || m == _sentinel ) continue;
 355     if( m->_idx == (uint)idx ) return m;
 356   }
 357   return NULL;
 358 }
 359 #endif
 360 
 361 #ifdef ASSERT
 362 NodeHash::~NodeHash() {
 363   // Unlock all nodes upon destruction of table.
 364   if (_table != (Node**)badAddress)  clear();
 365 }
 366 
 367 void NodeHash::operator=(const NodeHash& nh) {
 368   // Unlock all nodes upon replacement of table.
 369   if (&nh == this)  return;
 370   if (_table != (Node**)badAddress)  clear();
 371   memcpy(this, &nh, sizeof(*this));
 372   // Do not increment hash_lock counts again.
 373   // Instead, be sure we never again use the source table.
 374   ((NodeHash*)&nh)->_table = (Node**)badAddress;
 375 }
 376 
 377 
 378 #endif
 379 
 380 
 381 //=============================================================================
 382 //------------------------------PhaseRemoveUseless-----------------------------
 383 // 1) Use a breadthfirst walk to collect useful nodes reachable from root.
 384 PhaseRemoveUseless::PhaseRemoveUseless( PhaseGVN *gvn, Unique_Node_List *worklist ) : Phase(Remove_Useless),
 385   _useful(Thread::current()->resource_area()) {
 386 
 387   // Implementation requires 'UseLoopSafepoints == true' and an edge from root
 388   // to each SafePointNode at a backward branch.  Inserted in add_safepoint().
 389   if( !UseLoopSafepoints || !OptoRemoveUseless ) return;
 390 
 391   // Identify nodes that are reachable from below, useful.
 392   C->identify_useful_nodes(_useful);
 393   // Update dead node list
 394   C->update_dead_node_list(_useful);
 395 
 396   // Remove all useless nodes from PhaseValues' recorded types
 397   // Must be done before disconnecting nodes to preserve hash-table-invariant
 398   gvn->remove_useless_nodes(_useful.member_set());
 399 
 400   // Remove all useless nodes from future worklist
 401   worklist->remove_useless_nodes(_useful.member_set());
 402 
 403   // Disconnect 'useless' nodes that are adjacent to useful nodes
 404   C->remove_useless_nodes(_useful);
 405 
 406   // Remove edges from "root" to each SafePoint at a backward branch.
 407   // They were inserted during parsing (see add_safepoint()) to make infinite
 408   // loops without calls or exceptions visible to root, i.e., useful.
 409   Node *root = C->root();
 410   if( root != NULL ) {
 411     for( uint i = root->req(); i < root->len(); ++i ) {
 412       Node *n = root->in(i);
 413       if( n != NULL && n->is_SafePoint() ) {
 414         root->rm_prec(i);
 415         --i;
 416       }
 417     }
 418   }
 419 }
 420 
 421 
 422 //=============================================================================
 423 //------------------------------PhaseTransform---------------------------------
 424 PhaseTransform::PhaseTransform( PhaseNumber pnum ) : Phase(pnum),
 425   _arena(Thread::current()->resource_area()),
 426   _nodes(_arena),
 427   _types(_arena)
 428 {
 429   init_con_caches();
 430 #ifndef PRODUCT
 431   clear_progress();
 432   clear_transforms();
 433   set_allow_progress(true);
 434 #endif
 435   // Force allocation for currently existing nodes
 436   _types.map(C->unique(), NULL);
 437 }
 438 
 439 //------------------------------PhaseTransform---------------------------------
 440 PhaseTransform::PhaseTransform( Arena *arena, PhaseNumber pnum ) : Phase(pnum),
 441   _arena(arena),
 442   _nodes(arena),
 443   _types(arena)
 444 {
 445   init_con_caches();
 446 #ifndef PRODUCT
 447   clear_progress();
 448   clear_transforms();
 449   set_allow_progress(true);
 450 #endif
 451   // Force allocation for currently existing nodes
 452   _types.map(C->unique(), NULL);
 453 }
 454 
 455 //------------------------------PhaseTransform---------------------------------
 456 // Initialize with previously generated type information
 457 PhaseTransform::PhaseTransform( PhaseTransform *pt, PhaseNumber pnum ) : Phase(pnum),
 458   _arena(pt->_arena),
 459   _nodes(pt->_nodes),
 460   _types(pt->_types)
 461 {
 462   init_con_caches();
 463 #ifndef PRODUCT
 464   clear_progress();
 465   clear_transforms();
 466   set_allow_progress(true);
 467 #endif
 468 }
 469 
 470 void PhaseTransform::init_con_caches() {
 471   memset(_icons,0,sizeof(_icons));
 472   memset(_lcons,0,sizeof(_lcons));
 473   memset(_zcons,0,sizeof(_zcons));
 474 }
 475 
 476 
 477 //--------------------------------find_int_type--------------------------------
 478 const TypeInt* PhaseTransform::find_int_type(Node* n) {
 479   if (n == NULL)  return NULL;
 480   // Call type_or_null(n) to determine node's type since we might be in
 481   // parse phase and call n->Value() may return wrong type.
 482   // (For example, a phi node at the beginning of loop parsing is not ready.)
 483   const Type* t = type_or_null(n);
 484   if (t == NULL)  return NULL;
 485   return t->isa_int();
 486 }
 487 
 488 
 489 //-------------------------------find_long_type--------------------------------
 490 const TypeLong* PhaseTransform::find_long_type(Node* n) {
 491   if (n == NULL)  return NULL;
 492   // (See comment above on type_or_null.)
 493   const Type* t = type_or_null(n);
 494   if (t == NULL)  return NULL;
 495   return t->isa_long();
 496 }
 497 
 498 
 499 #ifndef PRODUCT
 500 void PhaseTransform::dump_old2new_map() const {
 501   _nodes.dump();
 502 }
 503 
 504 void PhaseTransform::dump_new( uint nidx ) const {
 505   for( uint i=0; i<_nodes.Size(); i++ )
 506     if( _nodes[i] && _nodes[i]->_idx == nidx ) {
 507       _nodes[i]->dump();
 508       tty->cr();
 509       tty->print_cr("Old index= %d",i);
 510       return;
 511     }
 512   tty->print_cr("Node %d not found in the new indices", nidx);
 513 }
 514 
 515 //------------------------------dump_types-------------------------------------
 516 void PhaseTransform::dump_types( ) const {
 517   _types.dump();
 518 }
 519 
 520 //------------------------------dump_nodes_and_types---------------------------
 521 void PhaseTransform::dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl) {
 522   VectorSet visited(Thread::current()->resource_area());
 523   dump_nodes_and_types_recur( root, depth, only_ctrl, visited );
 524 }
 525 
 526 //------------------------------dump_nodes_and_types_recur---------------------
 527 void PhaseTransform::dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited) {
 528   if( !n ) return;
 529   if( depth == 0 ) return;
 530   if( visited.test_set(n->_idx) ) return;
 531   for( uint i=0; i<n->len(); i++ ) {
 532     if( only_ctrl && !(n->is_Region()) && i != TypeFunc::Control ) continue;
 533     dump_nodes_and_types_recur( n->in(i), depth-1, only_ctrl, visited );
 534   }
 535   n->dump();
 536   if (type_or_null(n) != NULL) {
 537     tty->print("      "); type(n)->dump(); tty->cr();
 538   }
 539 }
 540 
 541 #endif
 542 
 543 
 544 //=============================================================================
 545 //------------------------------PhaseValues------------------------------------
 546 // Set minimum table size to "255"
 547 PhaseValues::PhaseValues( Arena *arena, uint est_max_size ) : PhaseTransform(arena, GVN), _table(arena, est_max_size) {
 548   NOT_PRODUCT( clear_new_values(); )
 549 }
 550 
 551 //------------------------------PhaseValues------------------------------------
 552 // Set minimum table size to "255"
 553 PhaseValues::PhaseValues( PhaseValues *ptv ) : PhaseTransform( ptv, GVN ),
 554   _table(&ptv->_table) {
 555   NOT_PRODUCT( clear_new_values(); )
 556 }
 557 
 558 //------------------------------PhaseValues------------------------------------
 559 // Used by +VerifyOpto.  Clear out hash table but copy _types array.
 560 PhaseValues::PhaseValues( PhaseValues *ptv, const char *dummy ) : PhaseTransform( ptv, GVN ),
 561   _table(ptv->arena(),ptv->_table.size()) {
 562   NOT_PRODUCT( clear_new_values(); )
 563 }
 564 
 565 //------------------------------~PhaseValues-----------------------------------
 566 #ifndef PRODUCT
 567 PhaseValues::~PhaseValues() {
 568   _table.dump();
 569 
 570   // Statistics for value progress and efficiency
 571   if( PrintCompilation && Verbose && WizardMode ) {
 572     tty->print("\n%sValues: %d nodes ---> %d/%d (%d)",
 573       is_IterGVN() ? "Iter" : "    ", C->unique(), made_progress(), made_transforms(), made_new_values());
 574     if( made_transforms() != 0 ) {
 575       tty->print_cr("  ratio %f", made_progress()/(float)made_transforms() );
 576     } else {
 577       tty->cr();
 578     }
 579   }
 580 }
 581 #endif
 582 
 583 //------------------------------makecon----------------------------------------
 584 ConNode* PhaseTransform::makecon(const Type *t) {
 585   assert(t->singleton(), "must be a constant");
 586   assert(!t->empty() || t == Type::TOP, "must not be vacuous range");
 587   switch (t->base()) {  // fast paths
 588   case Type::Half:
 589   case Type::Top:  return (ConNode*) C->top();
 590   case Type::Int:  return intcon( t->is_int()->get_con() );
 591   case Type::Long: return longcon( t->is_long()->get_con() );
 592   }
 593   if (t->is_zero_type())
 594     return zerocon(t->basic_type());
 595   return uncached_makecon(t);
 596 }
 597 
 598 //--------------------------uncached_makecon-----------------------------------
 599 // Make an idealized constant - one of ConINode, ConPNode, etc.
 600 ConNode* PhaseValues::uncached_makecon(const Type *t) {
 601   assert(t->singleton(), "must be a constant");
 602   ConNode* x = ConNode::make(C, t);
 603   ConNode* k = (ConNode*)hash_find_insert(x); // Value numbering
 604   if (k == NULL) {
 605     set_type(x, t);             // Missed, provide type mapping
 606     GrowableArray<Node_Notes*>* nna = C->node_note_array();
 607     if (nna != NULL) {
 608       Node_Notes* loc = C->locate_node_notes(nna, x->_idx, true);
 609       loc->clear(); // do not put debug info on constants
 610     }
 611   } else {
 612     x->destruct();              // Hit, destroy duplicate constant
 613     x = k;                      // use existing constant
 614   }
 615   return x;
 616 }
 617 
 618 //------------------------------intcon-----------------------------------------
 619 // Fast integer constant.  Same as "transform(new ConINode(TypeInt::make(i)))"
 620 ConINode* PhaseTransform::intcon(int i) {
 621   // Small integer?  Check cache! Check that cached node is not dead
 622   if (i >= _icon_min && i <= _icon_max) {
 623     ConINode* icon = _icons[i-_icon_min];
 624     if (icon != NULL && icon->in(TypeFunc::Control) != NULL)
 625       return icon;
 626   }
 627   ConINode* icon = (ConINode*) uncached_makecon(TypeInt::make(i));
 628   assert(icon->is_Con(), "");
 629   if (i >= _icon_min && i <= _icon_max)
 630     _icons[i-_icon_min] = icon;   // Cache small integers
 631   return icon;
 632 }
 633 
 634 //------------------------------longcon----------------------------------------
 635 // Fast long constant.
 636 ConLNode* PhaseTransform::longcon(jlong l) {
 637   // Small integer?  Check cache! Check that cached node is not dead
 638   if (l >= _lcon_min && l <= _lcon_max) {
 639     ConLNode* lcon = _lcons[l-_lcon_min];
 640     if (lcon != NULL && lcon->in(TypeFunc::Control) != NULL)
 641       return lcon;
 642   }
 643   ConLNode* lcon = (ConLNode*) uncached_makecon(TypeLong::make(l));
 644   assert(lcon->is_Con(), "");
 645   if (l >= _lcon_min && l <= _lcon_max)
 646     _lcons[l-_lcon_min] = lcon;      // Cache small integers
 647   return lcon;
 648 }
 649 
 650 //------------------------------zerocon-----------------------------------------
 651 // Fast zero or null constant. Same as "transform(ConNode::make(Type::get_zero_type(bt)))"
 652 ConNode* PhaseTransform::zerocon(BasicType bt) {
 653   assert((uint)bt <= _zcon_max, "domain check");
 654   ConNode* zcon = _zcons[bt];
 655   if (zcon != NULL && zcon->in(TypeFunc::Control) != NULL)
 656     return zcon;
 657   zcon = (ConNode*) uncached_makecon(Type::get_zero_type(bt));
 658   _zcons[bt] = zcon;
 659   return zcon;
 660 }
 661 
 662 
 663 
 664 //=============================================================================
 665 //------------------------------transform--------------------------------------
 666 // Return a node which computes the same function as this node, but in a
 667 // faster or cheaper fashion.
 668 Node *PhaseGVN::transform( Node *n ) {
 669   return transform_no_reclaim(n);
 670 }
 671 
 672 //------------------------------transform--------------------------------------
 673 // Return a node which computes the same function as this node, but
 674 // in a faster or cheaper fashion.
 675 Node *PhaseGVN::transform_no_reclaim( Node *n ) {
 676   NOT_PRODUCT( set_transforms(); )
 677 
 678   // Apply the Ideal call in a loop until it no longer applies
 679   Node *k = n;
 680   NOT_PRODUCT( uint loop_count = 0; )
 681   while( 1 ) {
 682     Node *i = k->Ideal(this, /*can_reshape=*/false);
 683     if( !i ) break;
 684     assert( i->_idx >= k->_idx, "Idealize should return new nodes, use Identity to return old nodes" );
 685     k = i;
 686     assert(loop_count++ < K, "infinite loop in PhaseGVN::transform");
 687   }
 688   NOT_PRODUCT( if( loop_count != 0 ) { set_progress(); } )
 689 
 690 
 691   // If brand new node, make space in type array.
 692   ensure_type_or_null(k);
 693 
 694   // Since I just called 'Value' to compute the set of run-time values
 695   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
 696   // cache Value.  Later requests for the local phase->type of this Node can
 697   // use the cached Value instead of suffering with 'bottom_type'.
 698   const Type *t = k->Value(this); // Get runtime Value set
 699   assert(t != NULL, "value sanity");
 700   if (type_or_null(k) != t) {
 701 #ifndef PRODUCT
 702     // Do not count initial visit to node as a transformation
 703     if (type_or_null(k) == NULL) {
 704       inc_new_values();
 705       set_progress();
 706     }
 707 #endif
 708     set_type(k, t);
 709     // If k is a TypeNode, capture any more-precise type permanently into Node
 710     k->raise_bottom_type(t);
 711   }
 712 
 713   if( t->singleton() && !k->is_Con() ) {
 714     NOT_PRODUCT( set_progress(); )
 715     return makecon(t);          // Turn into a constant
 716   }
 717 
 718   // Now check for Identities
 719   Node *i = k->Identity(this);  // Look for a nearby replacement
 720   if( i != k ) {                // Found? Return replacement!
 721     NOT_PRODUCT( set_progress(); )
 722     return i;
 723   }
 724 
 725   // Global Value Numbering
 726   i = hash_find_insert(k);      // Insert if new
 727   if( i && (i != k) ) {
 728     // Return the pre-existing node
 729     NOT_PRODUCT( set_progress(); )
 730     return i;
 731   }
 732 
 733   // Return Idealized original
 734   return k;
 735 }
 736 
 737 #ifdef ASSERT
 738 //------------------------------dead_loop_check--------------------------------
 739 // Check for a simple dead loop when a data node references itself directly
 740 // or through an other data node excluding cons and phis.
 741 void PhaseGVN::dead_loop_check( Node *n ) {
 742   // Phi may reference itself in a loop
 743   if (n != NULL && !n->is_dead_loop_safe() && !n->is_CFG()) {
 744     // Do 2 levels check and only data inputs.
 745     bool no_dead_loop = true;
 746     uint cnt = n->req();
 747     for (uint i = 1; i < cnt && no_dead_loop; i++) {
 748       Node *in = n->in(i);
 749       if (in == n) {
 750         no_dead_loop = false;
 751       } else if (in != NULL && !in->is_dead_loop_safe()) {
 752         uint icnt = in->req();
 753         for (uint j = 1; j < icnt && no_dead_loop; j++) {
 754           if (in->in(j) == n || in->in(j) == in)
 755             no_dead_loop = false;
 756         }
 757       }
 758     }
 759     if (!no_dead_loop) n->dump(3);
 760     assert(no_dead_loop, "dead loop detected");
 761   }
 762 }
 763 #endif
 764 
 765 //=============================================================================
 766 //------------------------------PhaseIterGVN-----------------------------------
 767 // Initialize hash table to fresh and clean for +VerifyOpto
 768 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn, const char *dummy ) : PhaseGVN(igvn,dummy), _worklist( ),
 769                                                                       _stack(C->unique() >> 1),
 770                                                                       _delay_transform(false) {
 771 }
 772 
 773 //------------------------------PhaseIterGVN-----------------------------------
 774 // Initialize with previous PhaseIterGVN info; used by PhaseCCP
 775 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn ) : PhaseGVN(igvn),
 776                                                    _worklist( igvn->_worklist ),
 777                                                    _stack( igvn->_stack ),
 778                                                    _delay_transform(igvn->_delay_transform)
 779 {
 780 }
 781 
 782 //------------------------------PhaseIterGVN-----------------------------------
 783 // Initialize with previous PhaseGVN info from Parser
 784 PhaseIterGVN::PhaseIterGVN( PhaseGVN *gvn ) : PhaseGVN(gvn),
 785                                               _worklist(*C->for_igvn()),
 786                                               _stack(C->unique() >> 1),
 787                                               _delay_transform(false)
 788 {
 789   uint max;
 790 
 791   // Dead nodes in the hash table inherited from GVN were not treated as
 792   // roots during def-use info creation; hence they represent an invisible
 793   // use.  Clear them out.
 794   max = _table.size();
 795   for( uint i = 0; i < max; ++i ) {
 796     Node *n = _table.at(i);
 797     if(n != NULL && n != _table.sentinel() && n->outcnt() == 0) {
 798       if( n->is_top() ) continue;
 799       assert( false, "Parse::remove_useless_nodes missed this node");
 800       hash_delete(n);
 801     }
 802   }
 803 
 804   // Any Phis or Regions on the worklist probably had uses that could not
 805   // make more progress because the uses were made while the Phis and Regions
 806   // were in half-built states.  Put all uses of Phis and Regions on worklist.
 807   max = _worklist.size();
 808   for( uint j = 0; j < max; j++ ) {
 809     Node *n = _worklist.at(j);
 810     uint uop = n->Opcode();
 811     if( uop == Op_Phi || uop == Op_Region ||
 812         n->is_Type() ||
 813         n->is_Mem() )
 814       add_users_to_worklist(n);
 815   }
 816 }
 817 
 818 
 819 #ifndef PRODUCT
 820 void PhaseIterGVN::verify_step(Node* n) {
 821   _verify_window[_verify_counter % _verify_window_size] = n;
 822   ++_verify_counter;
 823   ResourceMark rm;
 824   ResourceArea *area = Thread::current()->resource_area();
 825   VectorSet old_space(area), new_space(area);
 826   if (C->unique() < 1000 ||
 827       0 == _verify_counter % (C->unique() < 10000 ? 10 : 100)) {
 828     ++_verify_full_passes;
 829     Node::verify_recur(C->root(), -1, old_space, new_space);
 830   }
 831   const int verify_depth = 4;
 832   for ( int i = 0; i < _verify_window_size; i++ ) {
 833     Node* n = _verify_window[i];
 834     if ( n == NULL )  continue;
 835     if( n->in(0) == NodeSentinel ) {  // xform_idom
 836       _verify_window[i] = n->in(1);
 837       --i; continue;
 838     }
 839     // Typical fanout is 1-2, so this call visits about 6 nodes.
 840     Node::verify_recur(n, verify_depth, old_space, new_space);
 841   }
 842 }
 843 #endif
 844 
 845 
 846 //------------------------------init_worklist----------------------------------
 847 // Initialize worklist for each node.
 848 void PhaseIterGVN::init_worklist( Node *n ) {
 849   if( _worklist.member(n) ) return;
 850   _worklist.push(n);
 851   uint cnt = n->req();
 852   for( uint i =0 ; i < cnt; i++ ) {
 853     Node *m = n->in(i);
 854     if( m ) init_worklist(m);
 855   }
 856 }
 857 
 858 //------------------------------optimize---------------------------------------
 859 void PhaseIterGVN::optimize() {
 860   debug_only(uint num_processed  = 0;);
 861 #ifndef PRODUCT
 862   {
 863     _verify_counter = 0;
 864     _verify_full_passes = 0;
 865     for ( int i = 0; i < _verify_window_size; i++ ) {
 866       _verify_window[i] = NULL;
 867     }
 868   }
 869 #endif
 870 
 871 #ifdef ASSERT
 872   Node* prev = NULL;
 873   uint rep_cnt = 0;
 874 #endif
 875   uint loop_count = 0;
 876 
 877   // Pull from worklist; transform node;
 878   // If node has changed: update edge info and put uses on worklist.
 879   while( _worklist.size() ) {
 880     if (C->check_node_count(NodeLimitFudgeFactor * 2,
 881                             "out of nodes optimizing method")) {
 882       return;
 883     }
 884     Node *n  = _worklist.pop();
 885     if (++loop_count >= K * C->live_nodes()) {
 886       debug_only(n->dump(4);)
 887       assert(false, "infinite loop in PhaseIterGVN::optimize");
 888       C->record_method_not_compilable("infinite loop in PhaseIterGVN::optimize");
 889       return;
 890     }
 891 #ifdef ASSERT
 892     if (n == prev) {
 893       if (++rep_cnt > 3) {
 894         n->dump(4);
 895         assert(false, "loop in Ideal transformation");
 896       }
 897     } else {
 898       rep_cnt = 0;
 899     }
 900     prev = n;
 901 #endif
 902     if (TraceIterativeGVN && Verbose) {
 903       tty->print("  Pop ");
 904       NOT_PRODUCT( n->dump(); )
 905       debug_only(if( (num_processed++ % 100) == 0 ) _worklist.print_set();)
 906     }
 907 
 908     if (n->outcnt() != 0) {
 909 
 910 #ifndef PRODUCT
 911       uint wlsize = _worklist.size();
 912       const Type* oldtype = type_or_null(n);
 913 #endif //PRODUCT
 914 
 915       Node *nn = transform_old(n);
 916 
 917 #ifndef PRODUCT
 918       if (TraceIterativeGVN) {
 919         const Type* newtype = type_or_null(n);
 920         if (nn != n) {
 921           // print old node
 922           tty->print("< ");
 923           if (oldtype != newtype && oldtype != NULL) {
 924             oldtype->dump();
 925           }
 926           do { tty->print("\t"); } while (tty->position() < 16);
 927           tty->print("<");
 928           n->dump();
 929         }
 930         if (oldtype != newtype || nn != n) {
 931           // print new node and/or new type
 932           if (oldtype == NULL) {
 933             tty->print("* ");
 934           } else if (nn != n) {
 935             tty->print("> ");
 936           } else {
 937             tty->print("= ");
 938           }
 939           if (newtype == NULL) {
 940             tty->print("null");
 941           } else {
 942             newtype->dump();
 943           }
 944           do { tty->print("\t"); } while (tty->position() < 16);
 945           nn->dump();
 946         }
 947         if (Verbose && wlsize < _worklist.size()) {
 948           tty->print("  Push {");
 949           while (wlsize != _worklist.size()) {
 950             Node* pushed = _worklist.at(wlsize++);
 951             tty->print(" %d", pushed->_idx);
 952           }
 953           tty->print_cr(" }");
 954         }
 955       }
 956       if( VerifyIterativeGVN && nn != n ) {
 957         verify_step((Node*) NULL);  // ignore n, it might be subsumed
 958       }
 959 #endif
 960     } else if (!n->is_top()) {
 961       remove_dead_node(n);
 962     }
 963   }
 964 
 965 #ifndef PRODUCT
 966   C->verify_graph_edges();
 967   if( VerifyOpto && allow_progress() ) {
 968     // Must turn off allow_progress to enable assert and break recursion
 969     C->root()->verify();
 970     { // Check if any progress was missed using IterGVN
 971       // Def-Use info enables transformations not attempted in wash-pass
 972       // e.g. Region/Phi cleanup, ...
 973       // Null-check elision -- may not have reached fixpoint
 974       //                       do not propagate to dominated nodes
 975       ResourceMark rm;
 976       PhaseIterGVN igvn2(this,"Verify"); // Fresh and clean!
 977       // Fill worklist completely
 978       igvn2.init_worklist(C->root());
 979 
 980       igvn2.set_allow_progress(false);
 981       igvn2.optimize();
 982       igvn2.set_allow_progress(true);
 983     }
 984   }
 985   if ( VerifyIterativeGVN && PrintOpto ) {
 986     if ( _verify_counter == _verify_full_passes )
 987       tty->print_cr("VerifyIterativeGVN: %d transforms and verify passes",
 988                     _verify_full_passes);
 989     else
 990       tty->print_cr("VerifyIterativeGVN: %d transforms, %d full verify passes",
 991                   _verify_counter, _verify_full_passes);
 992   }
 993 #endif
 994 }
 995 
 996 
 997 //------------------register_new_node_with_optimizer---------------------------
 998 // Register a new node with the optimizer.  Update the types array, the def-use
 999 // info.  Put on worklist.
1000 Node* PhaseIterGVN::register_new_node_with_optimizer(Node* n, Node* orig) {
1001   set_type_bottom(n);
1002   _worklist.push(n);
1003   if (orig != NULL)  C->copy_node_notes_to(n, orig);
1004   return n;
1005 }
1006 
1007 //------------------------------transform--------------------------------------
1008 // Non-recursive: idealize Node 'n' with respect to its inputs and its value
1009 Node *PhaseIterGVN::transform( Node *n ) {
1010   if (_delay_transform) {
1011     // Register the node but don't optimize for now
1012     register_new_node_with_optimizer(n);
1013     return n;
1014   }
1015 
1016   // If brand new node, make space in type array, and give it a type.
1017   ensure_type_or_null(n);
1018   if (type_or_null(n) == NULL) {
1019     set_type_bottom(n);
1020   }
1021 
1022   return transform_old(n);
1023 }
1024 
1025 //------------------------------transform_old----------------------------------
1026 Node *PhaseIterGVN::transform_old( Node *n ) {
1027 #ifndef PRODUCT
1028   debug_only(uint loop_count = 0;);
1029   set_transforms();
1030 #endif
1031   // Remove 'n' from hash table in case it gets modified
1032   _table.hash_delete(n);
1033   if( VerifyIterativeGVN ) {
1034    assert( !_table.find_index(n->_idx), "found duplicate entry in table");
1035   }
1036 
1037   // Apply the Ideal call in a loop until it no longer applies
1038   Node *k = n;
1039   DEBUG_ONLY(dead_loop_check(k);)
1040   DEBUG_ONLY(bool is_new = (k->outcnt() == 0);)
1041   Node *i = k->Ideal(this, /*can_reshape=*/true);
1042   assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes");
1043 #ifndef PRODUCT
1044   if( VerifyIterativeGVN )
1045     verify_step(k);
1046   if( i && VerifyOpto ) {
1047     if( !allow_progress() ) {
1048       if (i->is_Add() && i->outcnt() == 1) {
1049         // Switched input to left side because this is the only use
1050       } else if( i->is_If() && (i->in(0) == NULL) ) {
1051         // This IF is dead because it is dominated by an equivalent IF When
1052         // dominating if changed, info is not propagated sparsely to 'this'
1053         // Propagating this info further will spuriously identify other
1054         // progress.
1055         return i;
1056       } else
1057         set_progress();
1058     } else
1059       set_progress();
1060   }
1061 #endif
1062 
1063   while( i ) {
1064 #ifndef PRODUCT
1065     debug_only( if( loop_count >= K ) i->dump(4); )
1066     assert(loop_count < K, "infinite loop in PhaseIterGVN::transform");
1067     debug_only( loop_count++; )
1068 #endif
1069     assert((i->_idx >= k->_idx) || i->is_top(), "Idealize should return new nodes, use Identity to return old nodes");
1070     // Made a change; put users of original Node on worklist
1071     add_users_to_worklist( k );
1072     // Replacing root of transform tree?
1073     if( k != i ) {
1074       // Make users of old Node now use new.
1075       subsume_node( k, i );
1076       k = i;
1077     }
1078     DEBUG_ONLY(dead_loop_check(k);)
1079     // Try idealizing again
1080     DEBUG_ONLY(is_new = (k->outcnt() == 0);)
1081     i = k->Ideal(this, /*can_reshape=*/true);
1082     assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes");
1083 #ifndef PRODUCT
1084     if( VerifyIterativeGVN )
1085       verify_step(k);
1086     if( i && VerifyOpto ) set_progress();
1087 #endif
1088   }
1089 
1090   // If brand new node, make space in type array.
1091   ensure_type_or_null(k);
1092 
1093   // See what kind of values 'k' takes on at runtime
1094   const Type *t = k->Value(this);
1095   assert(t != NULL, "value sanity");
1096 
1097   // Since I just called 'Value' to compute the set of run-time values
1098   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
1099   // cache Value.  Later requests for the local phase->type of this Node can
1100   // use the cached Value instead of suffering with 'bottom_type'.
1101   if (t != type_or_null(k)) {
1102     NOT_PRODUCT( set_progress(); )
1103     NOT_PRODUCT( inc_new_values();)
1104     set_type(k, t);
1105     // If k is a TypeNode, capture any more-precise type permanently into Node
1106     k->raise_bottom_type(t);
1107     // Move users of node to worklist
1108     add_users_to_worklist( k );
1109   }
1110 
1111   // If 'k' computes a constant, replace it with a constant
1112   if( t->singleton() && !k->is_Con() ) {
1113     NOT_PRODUCT( set_progress(); )
1114     Node *con = makecon(t);     // Make a constant
1115     add_users_to_worklist( k );
1116     subsume_node( k, con );     // Everybody using k now uses con
1117     return con;
1118   }
1119 
1120   // Now check for Identities
1121   i = k->Identity(this);        // Look for a nearby replacement
1122   if( i != k ) {                // Found? Return replacement!
1123     NOT_PRODUCT( set_progress(); )
1124     add_users_to_worklist( k );
1125     subsume_node( k, i );       // Everybody using k now uses i
1126     return i;
1127   }
1128 
1129   // Global Value Numbering
1130   i = hash_find_insert(k);      // Check for pre-existing node
1131   if( i && (i != k) ) {
1132     // Return the pre-existing node if it isn't dead
1133     NOT_PRODUCT( set_progress(); )
1134     add_users_to_worklist( k );
1135     subsume_node( k, i );       // Everybody using k now uses i
1136     return i;
1137   }
1138 
1139   // Return Idealized original
1140   return k;
1141 }
1142 
1143 //---------------------------------saturate------------------------------------
1144 const Type* PhaseIterGVN::saturate(const Type* new_type, const Type* old_type,
1145                                    const Type* limit_type) const {
1146   return new_type->narrow(old_type);
1147 }
1148 
1149 //------------------------------remove_globally_dead_node----------------------
1150 // Kill a globally dead Node.  All uses are also globally dead and are
1151 // aggressively trimmed.
1152 void PhaseIterGVN::remove_globally_dead_node( Node *dead ) {
1153   enum DeleteProgress {
1154     PROCESS_INPUTS,
1155     PROCESS_OUTPUTS
1156   };
1157   assert(_stack.is_empty(), "not empty");
1158   _stack.push(dead, PROCESS_INPUTS);
1159 
1160   while (_stack.is_nonempty()) {
1161     dead = _stack.node();
1162     uint progress_state = _stack.index();
1163     assert(dead != C->root(), "killing root, eh?");
1164     assert(!dead->is_top(), "add check for top when pushing");
1165     NOT_PRODUCT( set_progress(); )
1166     if (progress_state == PROCESS_INPUTS) {
1167       // After following inputs, continue to outputs
1168       _stack.set_index(PROCESS_OUTPUTS);
1169       if (!dead->is_Con()) { // Don't kill cons but uses
1170         bool recurse = false;
1171         // Remove from hash table
1172         _table.hash_delete( dead );
1173         // Smash all inputs to 'dead', isolating him completely
1174         for (uint i = 0; i < dead->req(); i++) {
1175           Node *in = dead->in(i);
1176           if (in != NULL && in != C->top()) {  // Points to something?
1177             int nrep = dead->replace_edge(in, NULL);  // Kill edges
1178             assert((nrep > 0), "sanity");
1179             if (in->outcnt() == 0) { // Made input go dead?
1180               _stack.push(in, PROCESS_INPUTS); // Recursively remove
1181               recurse = true;
1182             } else if (in->outcnt() == 1 &&
1183                        in->has_special_unique_user()) {
1184               _worklist.push(in->unique_out());
1185             } else if (in->outcnt() <= 2 && dead->is_Phi()) {
1186               if (in->Opcode() == Op_Region) {
1187                 _worklist.push(in);
1188               } else if (in->is_Store()) {
1189                 DUIterator_Fast imax, i = in->fast_outs(imax);
1190                 _worklist.push(in->fast_out(i));
1191                 i++;
1192                 if (in->outcnt() == 2) {
1193                   _worklist.push(in->fast_out(i));
1194                   i++;
1195                 }
1196                 assert(!(i < imax), "sanity");
1197               }
1198             }
1199             if (ReduceFieldZeroing && dead->is_Load() && i == MemNode::Memory &&
1200                 in->is_Proj() && in->in(0) != NULL && in->in(0)->is_Initialize()) {
1201               // A Load that directly follows an InitializeNode is
1202               // going away. The Stores that follow are candidates
1203               // again to be captured by the InitializeNode.
1204               for (DUIterator_Fast jmax, j = in->fast_outs(jmax); j < jmax; j++) {
1205                 Node *n = in->fast_out(j);
1206                 if (n->is_Store()) {
1207                   _worklist.push(n);
1208                 }
1209               }
1210             }
1211           } // if (in != NULL && in != C->top())
1212         } // for (uint i = 0; i < dead->req(); i++)
1213         if (recurse) {
1214           continue;
1215         }
1216       } // if (!dead->is_Con())
1217     } // if (progress_state == PROCESS_INPUTS)
1218 
1219     // Aggressively kill globally dead uses
1220     // (Rather than pushing all the outs at once, we push one at a time,
1221     // plus the parent to resume later, because of the indefinite number
1222     // of edge deletions per loop trip.)
1223     if (dead->outcnt() > 0) {
1224       // Recursively remove output edges
1225       _stack.push(dead->raw_out(0), PROCESS_INPUTS);
1226     } else {
1227       // Finished disconnecting all input and output edges.
1228       _stack.pop();
1229       // Remove dead node from iterative worklist
1230       _worklist.remove(dead);
1231       // Constant node that has no out-edges and has only one in-edge from
1232       // root is usually dead. However, sometimes reshaping walk makes
1233       // it reachable by adding use edges. So, we will NOT count Con nodes
1234       // as dead to be conservative about the dead node count at any
1235       // given time.
1236       if (!dead->is_Con()) {
1237         C->record_dead_node(dead->_idx);
1238       }
1239       if (dead->is_macro()) {
1240         C->remove_macro_node(dead);
1241       }
1242       if (dead->is_expensive()) {
1243         C->remove_expensive_node(dead);
1244       }
1245     }
1246   } // while (_stack.is_nonempty())
1247 }
1248 
1249 //------------------------------subsume_node-----------------------------------
1250 // Remove users from node 'old' and add them to node 'nn'.
1251 void PhaseIterGVN::subsume_node( Node *old, Node *nn ) {
1252   assert( old != hash_find(old), "should already been removed" );
1253   assert( old != C->top(), "cannot subsume top node");
1254   // Copy debug or profile information to the new version:
1255   C->copy_node_notes_to(nn, old);
1256   // Move users of node 'old' to node 'nn'
1257   for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) {
1258     Node* use = old->last_out(i);  // for each use...
1259     // use might need re-hashing (but it won't if it's a new node)
1260     bool is_in_table = _table.hash_delete( use );
1261     // Update use-def info as well
1262     // We remove all occurrences of old within use->in,
1263     // so as to avoid rehashing any node more than once.
1264     // The hash table probe swamps any outer loop overhead.
1265     uint num_edges = 0;
1266     for (uint jmax = use->len(), j = 0; j < jmax; j++) {
1267       if (use->in(j) == old) {
1268         use->set_req(j, nn);
1269         ++num_edges;
1270       }
1271     }
1272     // Insert into GVN hash table if unique
1273     // If a duplicate, 'use' will be cleaned up when pulled off worklist
1274     if( is_in_table ) {
1275       hash_find_insert(use);
1276     }
1277     i -= num_edges;    // we deleted 1 or more copies of this edge
1278   }
1279 
1280   // Smash all inputs to 'old', isolating him completely
1281   Node *temp = new (C) Node(1);
1282   temp->init_req(0,nn);     // Add a use to nn to prevent him from dying
1283   remove_dead_node( old );
1284   temp->del_req(0);         // Yank bogus edge
1285 #ifndef PRODUCT
1286   if( VerifyIterativeGVN ) {
1287     for ( int i = 0; i < _verify_window_size; i++ ) {
1288       if ( _verify_window[i] == old )
1289         _verify_window[i] = nn;
1290     }
1291   }
1292 #endif
1293   _worklist.remove(temp);   // this can be necessary
1294   temp->destruct();         // reuse the _idx of this little guy
1295 }
1296 
1297 //------------------------------add_users_to_worklist--------------------------
1298 void PhaseIterGVN::add_users_to_worklist0( Node *n ) {
1299   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1300     _worklist.push(n->fast_out(i));  // Push on worklist
1301   }
1302 }
1303 
1304 void PhaseIterGVN::add_users_to_worklist( Node *n ) {
1305   add_users_to_worklist0(n);
1306 
1307   // Move users of node to worklist
1308   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1309     Node* use = n->fast_out(i); // Get use
1310 
1311     if( use->is_Multi() ||      // Multi-definer?  Push projs on worklist
1312         use->is_Store() )       // Enable store/load same address
1313       add_users_to_worklist0(use);
1314 
1315     // If we changed the receiver type to a call, we need to revisit
1316     // the Catch following the call.  It's looking for a non-NULL
1317     // receiver to know when to enable the regular fall-through path
1318     // in addition to the NullPtrException path.
1319     if (use->is_CallDynamicJava() && n == use->in(TypeFunc::Parms)) {
1320       Node* p = use->as_CallDynamicJava()->proj_out(TypeFunc::Control);
1321       if (p != NULL) {
1322         add_users_to_worklist0(p);
1323       }
1324     }
1325 
1326     if( use->is_Cmp() ) {       // Enable CMP/BOOL optimization
1327       add_users_to_worklist(use); // Put Bool on worklist
1328       // Look for the 'is_x2logic' pattern: "x ? : 0 : 1" and put the
1329       // phi merging either 0 or 1 onto the worklist
1330       if (use->outcnt() > 0) {
1331         Node* bol = use->raw_out(0);
1332         if (bol->outcnt() > 0) {
1333           Node* iff = bol->raw_out(0);
1334           if (iff->outcnt() == 2) {
1335             Node* ifproj0 = iff->raw_out(0);
1336             Node* ifproj1 = iff->raw_out(1);
1337             if (ifproj0->outcnt() > 0 && ifproj1->outcnt() > 0) {
1338               Node* region0 = ifproj0->raw_out(0);
1339               Node* region1 = ifproj1->raw_out(0);
1340               if( region0 == region1 )
1341                 add_users_to_worklist0(region0);
1342             }
1343           }
1344         }
1345       }
1346     }
1347 
1348     uint use_op = use->Opcode();
1349     // If changed Cast input, check Phi users for simple cycles
1350     if( use->is_ConstraintCast() || use->is_CheckCastPP() ) {
1351       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1352         Node* u = use->fast_out(i2);
1353         if (u->is_Phi())
1354           _worklist.push(u);
1355       }
1356     }
1357     // If changed LShift inputs, check RShift users for useless sign-ext
1358     if( use_op == Op_LShiftI ) {
1359       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1360         Node* u = use->fast_out(i2);
1361         if (u->Opcode() == Op_RShiftI)
1362           _worklist.push(u);
1363       }
1364     }
1365     // If changed AddP inputs, check Stores for loop invariant
1366     if( use_op == Op_AddP ) {
1367       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1368         Node* u = use->fast_out(i2);
1369         if (u->is_Mem())
1370           _worklist.push(u);
1371       }
1372     }
1373     // If changed initialization activity, check dependent Stores
1374     if (use_op == Op_Allocate || use_op == Op_AllocateArray) {
1375       InitializeNode* init = use->as_Allocate()->initialization();
1376       if (init != NULL) {
1377         Node* imem = init->proj_out(TypeFunc::Memory);
1378         if (imem != NULL)  add_users_to_worklist0(imem);
1379       }
1380     }
1381     if (use_op == Op_Initialize) {
1382       Node* imem = use->as_Initialize()->proj_out(TypeFunc::Memory);
1383       if (imem != NULL)  add_users_to_worklist0(imem);
1384     }
1385   }
1386 }
1387 
1388 // Remove the speculative part of all types that we know of
1389 void PhaseIterGVN::remove_speculative_types()  {
1390   assert(UseTypeSpeculation, "speculation is off");
1391   for (int i = 0; i < _types.Size(); i++)  {
1392     const Type* t = _types.fast_lookup(i);
1393     if (t != NULL && t->isa_oopptr()) {
1394       const TypeOopPtr* to = t->is_oopptr();
1395       _types.map(i, to->remove_speculative());
1396     }
1397   }
1398 }
1399 
1400 //=============================================================================
1401 #ifndef PRODUCT
1402 uint PhaseCCP::_total_invokes   = 0;
1403 uint PhaseCCP::_total_constants = 0;
1404 #endif
1405 //------------------------------PhaseCCP---------------------------------------
1406 // Conditional Constant Propagation, ala Wegman & Zadeck
1407 PhaseCCP::PhaseCCP( PhaseIterGVN *igvn ) : PhaseIterGVN(igvn) {
1408   NOT_PRODUCT( clear_constants(); )
1409   assert( _worklist.size() == 0, "" );
1410   // Clear out _nodes from IterGVN.  Must be clear to transform call.
1411   _nodes.clear();               // Clear out from IterGVN
1412   analyze();
1413 }
1414 
1415 #ifndef PRODUCT
1416 //------------------------------~PhaseCCP--------------------------------------
1417 PhaseCCP::~PhaseCCP() {
1418   inc_invokes();
1419   _total_constants += count_constants();
1420 }
1421 #endif
1422 
1423 
1424 #ifdef ASSERT
1425 static bool ccp_type_widens(const Type* t, const Type* t0) {
1426   assert(t->meet(t0) == t, "Not monotonic");
1427   switch (t->base() == t0->base() ? t->base() : Type::Top) {
1428   case Type::Int:
1429     assert(t0->isa_int()->_widen <= t->isa_int()->_widen, "widen increases");
1430     break;
1431   case Type::Long:
1432     assert(t0->isa_long()->_widen <= t->isa_long()->_widen, "widen increases");
1433     break;
1434   }
1435   return true;
1436 }
1437 #endif //ASSERT
1438 
1439 //------------------------------analyze----------------------------------------
1440 void PhaseCCP::analyze() {
1441   // Initialize all types to TOP, optimistic analysis
1442   for (int i = C->unique() - 1; i >= 0; i--)  {
1443     _types.map(i,Type::TOP);
1444   }
1445 
1446   // Push root onto worklist
1447   Unique_Node_List worklist;
1448   worklist.push(C->root());
1449 
1450   // Pull from worklist; compute new value; push changes out.
1451   // This loop is the meat of CCP.
1452   while( worklist.size() ) {
1453     Node *n = worklist.pop();
1454     const Type *t = n->Value(this);
1455     if (t != type(n)) {
1456       assert(ccp_type_widens(t, type(n)), "ccp type must widen");
1457 #ifndef PRODUCT
1458       if( TracePhaseCCP ) {
1459         t->dump();
1460         do { tty->print("\t"); } while (tty->position() < 16);
1461         n->dump();
1462       }
1463 #endif
1464       set_type(n, t);
1465       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1466         Node* m = n->fast_out(i);   // Get user
1467         if( m->is_Region() ) {  // New path to Region?  Must recheck Phis too
1468           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1469             Node* p = m->fast_out(i2); // Propagate changes to uses
1470             if( p->bottom_type() != type(p) ) // If not already bottomed out
1471               worklist.push(p); // Propagate change to user
1472           }
1473         }
1474         // If we changed the receiver type to a call, we need to revisit
1475         // the Catch following the call.  It's looking for a non-NULL
1476         // receiver to know when to enable the regular fall-through path
1477         // in addition to the NullPtrException path
1478         if (m->is_Call()) {
1479           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1480             Node* p = m->fast_out(i2);  // Propagate changes to uses
1481             if (p->is_Proj() && p->as_Proj()->_con == TypeFunc::Control && p->outcnt() == 1)
1482               worklist.push(p->unique_out());
1483           }
1484         }
1485         if( m->bottom_type() != type(m) ) // If not already bottomed out
1486           worklist.push(m);     // Propagate change to user
1487       }
1488     }
1489   }
1490 }
1491 
1492 //------------------------------do_transform-----------------------------------
1493 // Top level driver for the recursive transformer
1494 void PhaseCCP::do_transform() {
1495   // Correct leaves of new-space Nodes; they point to old-space.
1496   C->set_root( transform(C->root())->as_Root() );
1497   assert( C->top(),  "missing TOP node" );
1498   assert( C->root(), "missing root" );
1499 }
1500 
1501 //------------------------------transform--------------------------------------
1502 // Given a Node in old-space, clone him into new-space.
1503 // Convert any of his old-space children into new-space children.
1504 Node *PhaseCCP::transform( Node *n ) {
1505   Node *new_node = _nodes[n->_idx]; // Check for transformed node
1506   if( new_node != NULL )
1507     return new_node;                // Been there, done that, return old answer
1508   new_node = transform_once(n);     // Check for constant
1509   _nodes.map( n->_idx, new_node );  // Flag as having been cloned
1510 
1511   // Allocate stack of size _nodes.Size()/2 to avoid frequent realloc
1512   GrowableArray <Node *> trstack(C->unique() >> 1);
1513 
1514   trstack.push(new_node);           // Process children of cloned node
1515   while ( trstack.is_nonempty() ) {
1516     Node *clone = trstack.pop();
1517     uint cnt = clone->req();
1518     for( uint i = 0; i < cnt; i++ ) {          // For all inputs do
1519       Node *input = clone->in(i);
1520       if( input != NULL ) {                    // Ignore NULLs
1521         Node *new_input = _nodes[input->_idx]; // Check for cloned input node
1522         if( new_input == NULL ) {
1523           new_input = transform_once(input);   // Check for constant
1524           _nodes.map( input->_idx, new_input );// Flag as having been cloned
1525           trstack.push(new_input);
1526         }
1527         assert( new_input == clone->in(i), "insanity check");
1528       }
1529     }
1530   }
1531   return new_node;
1532 }
1533 
1534 
1535 //------------------------------transform_once---------------------------------
1536 // For PhaseCCP, transformation is IDENTITY unless Node computed a constant.
1537 Node *PhaseCCP::transform_once( Node *n ) {
1538   const Type *t = type(n);
1539   // Constant?  Use constant Node instead
1540   if( t->singleton() ) {
1541     Node *nn = n;               // Default is to return the original constant
1542     if( t == Type::TOP ) {
1543       // cache my top node on the Compile instance
1544       if( C->cached_top_node() == NULL || C->cached_top_node()->in(0) == NULL ) {
1545         C->set_cached_top_node( ConNode::make(C, Type::TOP) );
1546         set_type(C->top(), Type::TOP);
1547       }
1548       nn = C->top();
1549     }
1550     if( !n->is_Con() ) {
1551       if( t != Type::TOP ) {
1552         nn = makecon(t);        // ConNode::make(t);
1553         NOT_PRODUCT( inc_constants(); )
1554       } else if( n->is_Region() ) { // Unreachable region
1555         // Note: nn == C->top()
1556         n->set_req(0, NULL);        // Cut selfreference
1557         // Eagerly remove dead phis to avoid phis copies creation.
1558         for (DUIterator i = n->outs(); n->has_out(i); i++) {
1559           Node* m = n->out(i);
1560           if( m->is_Phi() ) {
1561             assert(type(m) == Type::TOP, "Unreachable region should not have live phis.");
1562             replace_node(m, nn);
1563             --i; // deleted this phi; rescan starting with next position
1564           }
1565         }
1566       }
1567       replace_node(n,nn);       // Update DefUse edges for new constant
1568     }
1569     return nn;
1570   }
1571 
1572   // If x is a TypeNode, capture any more-precise type permanently into Node
1573   if (t != n->bottom_type()) {
1574     hash_delete(n);             // changing bottom type may force a rehash
1575     n->raise_bottom_type(t);
1576     _worklist.push(n);          // n re-enters the hash table via the worklist
1577   }
1578 
1579   // Idealize graph using DU info.  Must clone() into new-space.
1580   // DU info is generally used to show profitability, progress or safety
1581   // (but generally not needed for correctness).
1582   Node *nn = n->Ideal_DU_postCCP(this);
1583 
1584   // TEMPORARY fix to ensure that 2nd GVN pass eliminates NULL checks
1585   switch( n->Opcode() ) {
1586   case Op_FastLock:      // Revisit FastLocks for lock coarsening
1587   case Op_If:
1588   case Op_CountedLoopEnd:
1589   case Op_Region:
1590   case Op_Loop:
1591   case Op_CountedLoop:
1592   case Op_Conv2B:
1593   case Op_Opaque1:
1594   case Op_Opaque2:
1595     _worklist.push(n);
1596     break;
1597   default:
1598     break;
1599   }
1600   if( nn ) {
1601     _worklist.push(n);
1602     // Put users of 'n' onto worklist for second igvn transform
1603     add_users_to_worklist(n);
1604     return nn;
1605   }
1606 
1607   return  n;
1608 }
1609 
1610 //---------------------------------saturate------------------------------------
1611 const Type* PhaseCCP::saturate(const Type* new_type, const Type* old_type,
1612                                const Type* limit_type) const {
1613   const Type* wide_type = new_type->widen(old_type, limit_type);
1614   if (wide_type != new_type) {          // did we widen?
1615     // If so, we may have widened beyond the limit type.  Clip it back down.
1616     new_type = wide_type->filter(limit_type);
1617   }
1618   return new_type;
1619 }
1620 
1621 //------------------------------print_statistics-------------------------------
1622 #ifndef PRODUCT
1623 void PhaseCCP::print_statistics() {
1624   tty->print_cr("CCP: %d  constants found: %d", _total_invokes, _total_constants);
1625 }
1626 #endif
1627 
1628 
1629 //=============================================================================
1630 #ifndef PRODUCT
1631 uint PhasePeephole::_total_peepholes = 0;
1632 #endif
1633 //------------------------------PhasePeephole----------------------------------
1634 // Conditional Constant Propagation, ala Wegman & Zadeck
1635 PhasePeephole::PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg )
1636   : PhaseTransform(Peephole), _regalloc(regalloc), _cfg(cfg) {
1637   NOT_PRODUCT( clear_peepholes(); )
1638 }
1639 
1640 #ifndef PRODUCT
1641 //------------------------------~PhasePeephole---------------------------------
1642 PhasePeephole::~PhasePeephole() {
1643   _total_peepholes += count_peepholes();
1644 }
1645 #endif
1646 
1647 //------------------------------transform--------------------------------------
1648 Node *PhasePeephole::transform( Node *n ) {
1649   ShouldNotCallThis();
1650   return NULL;
1651 }
1652 
1653 //------------------------------do_transform-----------------------------------
1654 void PhasePeephole::do_transform() {
1655   bool method_name_not_printed = true;
1656 
1657   // Examine each basic block
1658   for (uint block_number = 1; block_number < _cfg.number_of_blocks(); ++block_number) {
1659     Block* block = _cfg.get_block(block_number);
1660     bool block_not_printed = true;
1661 
1662     // and each instruction within a block
1663     uint end_index = block->number_of_nodes();
1664     // block->end_idx() not valid after PhaseRegAlloc
1665     for( uint instruction_index = 1; instruction_index < end_index; ++instruction_index ) {
1666       Node     *n = block->get_node(instruction_index);
1667       if( n->is_Mach() ) {
1668         MachNode *m = n->as_Mach();
1669         int deleted_count = 0;
1670         // check for peephole opportunities
1671         MachNode *m2 = m->peephole( block, instruction_index, _regalloc, deleted_count, C );
1672         if( m2 != NULL ) {
1673 #ifndef PRODUCT
1674           if( PrintOptoPeephole ) {
1675             // Print method, first time only
1676             if( C->method() && method_name_not_printed ) {
1677               C->method()->print_short_name(); tty->cr();
1678               method_name_not_printed = false;
1679             }
1680             // Print this block
1681             if( Verbose && block_not_printed) {
1682               tty->print_cr("in block");
1683               block->dump();
1684               block_not_printed = false;
1685             }
1686             // Print instructions being deleted
1687             for( int i = (deleted_count - 1); i >= 0; --i ) {
1688               block->get_node(instruction_index-i)->as_Mach()->format(_regalloc); tty->cr();
1689             }
1690             tty->print_cr("replaced with");
1691             // Print new instruction
1692             m2->format(_regalloc);
1693             tty->print("\n\n");
1694           }
1695 #endif
1696           // Remove old nodes from basic block and update instruction_index
1697           // (old nodes still exist and may have edges pointing to them
1698           //  as register allocation info is stored in the allocator using
1699           //  the node index to live range mappings.)
1700           uint safe_instruction_index = (instruction_index - deleted_count);
1701           for( ; (instruction_index > safe_instruction_index); --instruction_index ) {
1702             block->remove_node( instruction_index );
1703           }
1704           // install new node after safe_instruction_index
1705           block->insert_node(m2, safe_instruction_index + 1);
1706           end_index = block->number_of_nodes() - 1; // Recompute new block size
1707           NOT_PRODUCT( inc_peepholes(); )
1708         }
1709       }
1710     }
1711   }
1712 }
1713 
1714 //------------------------------print_statistics-------------------------------
1715 #ifndef PRODUCT
1716 void PhasePeephole::print_statistics() {
1717   tty->print_cr("Peephole: peephole rules applied: %d",  _total_peepholes);
1718 }
1719 #endif
1720 
1721 
1722 //=============================================================================
1723 //------------------------------set_req_X--------------------------------------
1724 void Node::set_req_X( uint i, Node *n, PhaseIterGVN *igvn ) {
1725   assert( is_not_dead(n), "can not use dead node");
1726   assert( igvn->hash_find(this) != this, "Need to remove from hash before changing edges" );
1727   Node *old = in(i);
1728   set_req(i, n);
1729 
1730   // old goes dead?
1731   if( old ) {
1732     switch (old->outcnt()) {
1733     case 0:
1734       // Put into the worklist to kill later. We do not kill it now because the
1735       // recursive kill will delete the current node (this) if dead-loop exists
1736       if (!old->is_top())
1737         igvn->_worklist.push( old );
1738       break;
1739     case 1:
1740       if( old->is_Store() || old->has_special_unique_user() )
1741         igvn->add_users_to_worklist( old );
1742       break;
1743     case 2:
1744       if( old->is_Store() )
1745         igvn->add_users_to_worklist( old );
1746       if( old->Opcode() == Op_Region )
1747         igvn->_worklist.push(old);
1748       break;
1749     case 3:
1750       if( old->Opcode() == Op_Region ) {
1751         igvn->_worklist.push(old);
1752         igvn->add_users_to_worklist( old );
1753       }
1754       break;
1755     default:
1756       break;
1757     }
1758   }
1759 
1760 }
1761 
1762 //-------------------------------replace_by-----------------------------------
1763 // Using def-use info, replace one node for another.  Follow the def-use info
1764 // to all users of the OLD node.  Then make all uses point to the NEW node.
1765 void Node::replace_by(Node *new_node) {
1766   assert(!is_top(), "top node has no DU info");
1767   for (DUIterator_Last imin, i = last_outs(imin); i >= imin; ) {
1768     Node* use = last_out(i);
1769     uint uses_found = 0;
1770     for (uint j = 0; j < use->len(); j++) {
1771       if (use->in(j) == this) {
1772         if (j < use->req())
1773               use->set_req(j, new_node);
1774         else  use->set_prec(j, new_node);
1775         uses_found++;
1776       }
1777     }
1778     i -= uses_found;    // we deleted 1 or more copies of this edge
1779   }
1780 }
1781 
1782 //=============================================================================
1783 //-----------------------------------------------------------------------------
1784 void Type_Array::grow( uint i ) {
1785   if( !_max ) {
1786     _max = 1;
1787     _types = (const Type**)_a->Amalloc( _max * sizeof(Type*) );
1788     _types[0] = NULL;
1789   }
1790   uint old = _max;
1791   while( i >= _max ) _max <<= 1;        // Double to fit
1792   _types = (const Type**)_a->Arealloc( _types, old*sizeof(Type*),_max*sizeof(Type*));
1793   memset( &_types[old], 0, (_max-old)*sizeof(Type*) );
1794 }
1795 
1796 //------------------------------dump-------------------------------------------
1797 #ifndef PRODUCT
1798 void Type_Array::dump() const {
1799   uint max = Size();
1800   for( uint i = 0; i < max; i++ ) {
1801     if( _types[i] != NULL ) {
1802       tty->print("  %d\t== ", i); _types[i]->dump(); tty->cr();
1803     }
1804   }
1805 }
1806 #endif