1 /*
   2  * Copyright (c) 1997, 2014, 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/idealGraphPrinter.hpp"
  31 #include "opto/loopnode.hpp"
  32 #include "opto/machnode.hpp"
  33 #include "opto/opcodes.hpp"
  34 #include "opto/phaseX.hpp"
  35 #include "opto/regalloc.hpp"
  36 #include "opto/rootnode.hpp"
  37 
  38 //=============================================================================
  39 #define NODE_HASH_MINIMUM_SIZE    255
  40 //------------------------------NodeHash---------------------------------------
  41 NodeHash::NodeHash(uint est_max_size) :
  42   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
  43   _a(Thread::current()->resource_area()),
  44   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) ), // (Node**)_a->Amalloc(_max * sizeof(Node*)) ),
  45   _inserts(0), _insert_limit( insert_limit() )
  46 #ifndef PRODUCT
  47   ,_look_probes(0), _lookup_hits(0), _lookup_misses(0),
  48   _delete_probes(0), _delete_hits(0), _delete_misses(0),
  49   _total_insert_probes(0), _total_inserts(0),
  50   _insert_probes(0), _grows(0)
  51 #endif
  52 {
  53   // _sentinel must be in the current node space
  54   _sentinel = new ProjNode(NULL, TypeFunc::Control);
  55   memset(_table,0,sizeof(Node*)*_max);
  56 }
  57 
  58 //------------------------------NodeHash---------------------------------------
  59 NodeHash::NodeHash(Arena *arena, uint est_max_size) :
  60   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
  61   _a(arena),
  62   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) ),
  63   _inserts(0), _insert_limit( insert_limit() )
  64 #ifndef PRODUCT
  65   ,_look_probes(0), _lookup_hits(0), _lookup_misses(0),
  66   _delete_probes(0), _delete_hits(0), _delete_misses(0),
  67   _total_insert_probes(0), _total_inserts(0),
  68   _insert_probes(0), _grows(0)
  69 #endif
  70 {
  71   // _sentinel must be in the current node space
  72   _sentinel = new ProjNode(NULL, TypeFunc::Control);
  73   memset(_table,0,sizeof(Node*)*_max);
  74 }
  75 
  76 //------------------------------NodeHash---------------------------------------
  77 NodeHash::NodeHash(NodeHash *nh) {
  78   debug_only(_table = (Node**)badAddress);   // interact correctly w/ operator=
  79   // just copy in all the fields
  80   *this = *nh;
  81   // nh->_sentinel must be in the current node space
  82 }
  83 
  84 void NodeHash::replace_with(NodeHash *nh) {
  85   debug_only(_table = (Node**)badAddress);   // interact correctly w/ operator=
  86   // just copy in all the fields
  87   *this = *nh;
  88   // nh->_sentinel must be in the current node space
  89 }
  90 
  91 //------------------------------hash_find--------------------------------------
  92 // Find in hash table
  93 Node *NodeHash::hash_find( const Node *n ) {
  94   // ((Node*)n)->set_hash( n->hash() );
  95   uint hash = n->hash();
  96   if (hash == Node::NO_HASH) {
  97     NOT_PRODUCT( _lookup_misses++ );
  98     return NULL;
  99   }
 100   uint key = hash & (_max-1);
 101   uint stride = key | 0x01;
 102   NOT_PRODUCT( _look_probes++ );
 103   Node *k = _table[key];        // Get hashed value
 104   if( !k ) {                    // ?Miss?
 105     NOT_PRODUCT( _lookup_misses++ );
 106     return NULL;                // Miss!
 107   }
 108 
 109   int op = n->Opcode();
 110   uint req = n->req();
 111   while( 1 ) {                  // While probing hash table
 112     if( k->req() == req &&      // Same count of inputs
 113         k->Opcode() == op ) {   // Same Opcode
 114       for( uint i=0; i<req; i++ )
 115         if( n->in(i)!=k->in(i)) // Different inputs?
 116           goto collision;       // "goto" is a speed hack...
 117       if( n->cmp(*k) ) {        // Check for any special bits
 118         NOT_PRODUCT( _lookup_hits++ );
 119         return k;               // Hit!
 120       }
 121     }
 122   collision:
 123     NOT_PRODUCT( _look_probes++ );
 124     key = (key + stride/*7*/) & (_max-1); // Stride through table with relative prime
 125     k = _table[key];            // Get hashed value
 126     if( !k ) {                  // ?Miss?
 127       NOT_PRODUCT( _lookup_misses++ );
 128       return NULL;              // Miss!
 129     }
 130   }
 131   ShouldNotReachHere();
 132   return NULL;
 133 }
 134 
 135 //------------------------------hash_find_insert-------------------------------
 136 // Find in hash table, insert if not already present
 137 // Used to preserve unique entries in hash table
 138 Node *NodeHash::hash_find_insert( Node *n ) {
 139   // n->set_hash( );
 140   uint hash = n->hash();
 141   if (hash == Node::NO_HASH) {
 142     NOT_PRODUCT( _lookup_misses++ );
 143     return NULL;
 144   }
 145   uint key = hash & (_max-1);
 146   uint stride = key | 0x01;     // stride must be relatively prime to table siz
 147   uint first_sentinel = 0;      // replace a sentinel if seen.
 148   NOT_PRODUCT( _look_probes++ );
 149   Node *k = _table[key];        // Get hashed value
 150   if( !k ) {                    // ?Miss?
 151     NOT_PRODUCT( _lookup_misses++ );
 152     _table[key] = n;            // Insert into table!
 153     debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 154     check_grow();               // Grow table if insert hit limit
 155     return NULL;                // Miss!
 156   }
 157   else if( k == _sentinel ) {
 158     first_sentinel = key;      // Can insert here
 159   }
 160 
 161   int op = n->Opcode();
 162   uint req = n->req();
 163   while( 1 ) {                  // While probing hash table
 164     if( k->req() == req &&      // Same count of inputs
 165         k->Opcode() == op ) {   // Same Opcode
 166       for( uint i=0; i<req; i++ )
 167         if( n->in(i)!=k->in(i)) // Different inputs?
 168           goto collision;       // "goto" is a speed hack...
 169       if( n->cmp(*k) ) {        // Check for any special bits
 170         NOT_PRODUCT( _lookup_hits++ );
 171         return k;               // Hit!
 172       }
 173     }
 174   collision:
 175     NOT_PRODUCT( _look_probes++ );
 176     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
 177     k = _table[key];            // Get hashed value
 178     if( !k ) {                  // ?Miss?
 179       NOT_PRODUCT( _lookup_misses++ );
 180       key = (first_sentinel == 0) ? key : first_sentinel; // ?saw sentinel?
 181       _table[key] = n;          // Insert into table!
 182       debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 183       check_grow();             // Grow table if insert hit limit
 184       return NULL;              // Miss!
 185     }
 186     else if( first_sentinel == 0 && k == _sentinel ) {
 187       first_sentinel = key;    // Can insert here
 188     }
 189 
 190   }
 191   ShouldNotReachHere();
 192   return NULL;
 193 }
 194 
 195 //------------------------------hash_insert------------------------------------
 196 // Insert into hash table
 197 void NodeHash::hash_insert( Node *n ) {
 198   // // "conflict" comments -- print nodes that conflict
 199   // bool conflict = false;
 200   // n->set_hash();
 201   uint hash = n->hash();
 202   if (hash == Node::NO_HASH) {
 203     return;
 204   }
 205   check_grow();
 206   uint key = hash & (_max-1);
 207   uint stride = key | 0x01;
 208 
 209   while( 1 ) {                  // While probing hash table
 210     NOT_PRODUCT( _insert_probes++ );
 211     Node *k = _table[key];      // Get hashed value
 212     if( !k || (k == _sentinel) ) break;       // Found a slot
 213     assert( k != n, "already inserted" );
 214     // if( PrintCompilation && PrintOptoStatistics && Verbose ) { tty->print("  conflict: "); k->dump(); conflict = true; }
 215     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
 216   }
 217   _table[key] = n;              // Insert into table!
 218   debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 219   // if( conflict ) { n->dump(); }
 220 }
 221 
 222 //------------------------------hash_delete------------------------------------
 223 // Replace in hash table with sentinel
 224 bool NodeHash::hash_delete( const Node *n ) {
 225   Node *k;
 226   uint hash = n->hash();
 227   if (hash == Node::NO_HASH) {
 228     NOT_PRODUCT( _delete_misses++ );
 229     return false;
 230   }
 231   uint key = hash & (_max-1);
 232   uint stride = key | 0x01;
 233   debug_only( uint counter = 0; );
 234   for( ; /* (k != NULL) && (k != _sentinel) */; ) {
 235     debug_only( counter++ );
 236     NOT_PRODUCT( _delete_probes++ );
 237     k = _table[key];            // Get hashed value
 238     if( !k ) {                  // Miss?
 239       NOT_PRODUCT( _delete_misses++ );
 240 #ifdef ASSERT
 241       if( VerifyOpto ) {
 242         for( uint i=0; i < _max; i++ )
 243           assert( _table[i] != n, "changed edges with rehashing" );
 244       }
 245 #endif
 246       return false;             // Miss! Not in chain
 247     }
 248     else if( n == k ) {
 249       NOT_PRODUCT( _delete_hits++ );
 250       _table[key] = _sentinel;  // Hit! Label as deleted entry
 251       debug_only(((Node*)n)->exit_hash_lock()); // Unlock the node upon removal from table.
 252       return true;
 253     }
 254     else {
 255       // collision: move through table with prime offset
 256       key = (key + stride/*7*/) & (_max-1);
 257       assert( counter <= _insert_limit, "Cycle in hash-table");
 258     }
 259   }
 260   ShouldNotReachHere();
 261   return false;
 262 }
 263 
 264 //------------------------------round_up---------------------------------------
 265 // Round up to nearest power of 2
 266 uint NodeHash::round_up( uint x ) {
 267   x += (x>>2);                  // Add 25% slop
 268   if( x <16 ) return 16;        // Small stuff
 269   uint i=16;
 270   while( i < x ) i <<= 1;       // Double to fit
 271   return i;                     // Return hash table size
 272 }
 273 
 274 //------------------------------grow-------------------------------------------
 275 // Grow _table to next power of 2 and insert old entries
 276 void  NodeHash::grow() {
 277   // Record old state
 278   uint   old_max   = _max;
 279   Node **old_table = _table;
 280   // Construct new table with twice the space
 281 #ifndef PRODUCT
 282   _grows++;
 283   _total_inserts       += _inserts;
 284   _total_insert_probes += _insert_probes;
 285   _insert_probes   = 0;
 286 #endif
 287   _inserts         = 0;
 288   _max     = _max << 1;
 289   _table   = NEW_ARENA_ARRAY( _a , Node* , _max ); // (Node**)_a->Amalloc( _max * sizeof(Node*) );
 290   memset(_table,0,sizeof(Node*)*_max);
 291   _insert_limit = insert_limit();
 292   // Insert old entries into the new table
 293   for( uint i = 0; i < old_max; i++ ) {
 294     Node *m = *old_table++;
 295     if( !m || m == _sentinel ) continue;
 296     debug_only(m->exit_hash_lock()); // Unlock the node upon removal from old table.
 297     hash_insert(m);
 298   }
 299 }
 300 
 301 //------------------------------clear------------------------------------------
 302 // Clear all entries in _table to NULL but keep storage
 303 void  NodeHash::clear() {
 304 #ifdef ASSERT
 305   // Unlock all nodes upon removal from table.
 306   for (uint i = 0; i < _max; i++) {
 307     Node* n = _table[i];
 308     if (!n || n == _sentinel)  continue;
 309     n->exit_hash_lock();
 310   }
 311 #endif
 312 
 313   memset( _table, 0, _max * sizeof(Node*) );
 314 }
 315 
 316 //-----------------------remove_useless_nodes----------------------------------
 317 // Remove useless nodes from value table,
 318 // implementation does not depend on hash function
 319 void NodeHash::remove_useless_nodes(VectorSet &useful) {
 320 
 321   // Dead nodes in the hash table inherited from GVN should not replace
 322   // existing nodes, remove dead nodes.
 323   uint max = size();
 324   Node *sentinel_node = sentinel();
 325   for( uint i = 0; i < max; ++i ) {
 326     Node *n = at(i);
 327     if(n != NULL && n != sentinel_node && !useful.test(n->_idx)) {
 328       debug_only(n->exit_hash_lock()); // Unlock the node when removed
 329       _table[i] = sentinel_node;       // Replace with placeholder
 330     }
 331   }
 332 }
 333 
 334 
 335 void NodeHash::check_no_speculative_types() {
 336 #ifdef ASSERT
 337   uint max = size();
 338   Node *sentinel_node = sentinel();
 339   for (uint i = 0; i < max; ++i) {
 340     Node *n = at(i);
 341     if(n != NULL && n != sentinel_node && n->is_Type() && n->outcnt() > 0) {
 342       TypeNode* tn = n->as_Type();
 343       const Type* t = tn->type();
 344       const Type* t_no_spec = t->remove_speculative();
 345       assert(t == t_no_spec, "dead node in hash table or missed node during speculative cleanup");
 346     }
 347   }
 348 #endif
 349 }
 350 
 351 #ifndef PRODUCT
 352 //------------------------------dump-------------------------------------------
 353 // Dump statistics for the hash table
 354 void NodeHash::dump() {
 355   _total_inserts       += _inserts;
 356   _total_insert_probes += _insert_probes;
 357   if (PrintCompilation && PrintOptoStatistics && Verbose && (_inserts > 0)) {
 358     if (WizardMode) {
 359       for (uint i=0; i<_max; i++) {
 360         if (_table[i])
 361           tty->print("%d/%d/%d ",i,_table[i]->hash()&(_max-1),_table[i]->_idx);
 362       }
 363     }
 364     tty->print("\nGVN Hash stats:  %d grows to %d max_size\n", _grows, _max);
 365     tty->print("  %d/%d (%8.1f%% full)\n", _inserts, _max, (double)_inserts/_max*100.0);
 366     tty->print("  %dp/(%dh+%dm) (%8.2f probes/lookup)\n", _look_probes, _lookup_hits, _lookup_misses, (double)_look_probes/(_lookup_hits+_lookup_misses));
 367     tty->print("  %dp/%di (%8.2f probes/insert)\n", _total_insert_probes, _total_inserts, (double)_total_insert_probes/_total_inserts);
 368     // sentinels increase lookup cost, but not insert cost
 369     assert((_lookup_misses+_lookup_hits)*4+100 >= _look_probes, "bad hash function");
 370     assert( _inserts+(_inserts>>3) < _max, "table too full" );
 371     assert( _inserts*3+100 >= _insert_probes, "bad hash function" );
 372   }
 373 }
 374 
 375 Node *NodeHash::find_index(uint idx) { // For debugging
 376   // Find an entry by its index value
 377   for( uint i = 0; i < _max; i++ ) {
 378     Node *m = _table[i];
 379     if( !m || m == _sentinel ) continue;
 380     if( m->_idx == (uint)idx ) return m;
 381   }
 382   return NULL;
 383 }
 384 #endif
 385 
 386 #ifdef ASSERT
 387 NodeHash::~NodeHash() {
 388   // Unlock all nodes upon destruction of table.
 389   if (_table != (Node**)badAddress)  clear();
 390 }
 391 
 392 void NodeHash::operator=(const NodeHash& nh) {
 393   // Unlock all nodes upon replacement of table.
 394   if (&nh == this)  return;
 395   if (_table != (Node**)badAddress)  clear();
 396   memcpy(this, &nh, sizeof(*this));
 397   // Do not increment hash_lock counts again.
 398   // Instead, be sure we never again use the source table.
 399   ((NodeHash*)&nh)->_table = (Node**)badAddress;
 400 }
 401 
 402 
 403 #endif
 404 
 405 
 406 //=============================================================================
 407 //------------------------------PhaseRemoveUseless-----------------------------
 408 // 1) Use a breadthfirst walk to collect useful nodes reachable from root.
 409 PhaseRemoveUseless::PhaseRemoveUseless( PhaseGVN *gvn, Unique_Node_List *worklist ) : Phase(Remove_Useless),
 410   _useful(Thread::current()->resource_area()) {
 411 
 412   // Implementation requires 'UseLoopSafepoints == true' and an edge from root
 413   // to each SafePointNode at a backward branch.  Inserted in add_safepoint().
 414   if( !UseLoopSafepoints || !OptoRemoveUseless ) return;
 415 
 416   // Identify nodes that are reachable from below, useful.
 417   C->identify_useful_nodes(_useful);
 418   // Update dead node list
 419   C->update_dead_node_list(_useful);
 420 
 421   // Remove all useless nodes from PhaseValues' recorded types
 422   // Must be done before disconnecting nodes to preserve hash-table-invariant
 423   gvn->remove_useless_nodes(_useful.member_set());
 424 
 425   // Remove all useless nodes from future worklist
 426   worklist->remove_useless_nodes(_useful.member_set());
 427 
 428   // Disconnect 'useless' nodes that are adjacent to useful nodes
 429   C->remove_useless_nodes(_useful);
 430 
 431   // Remove edges from "root" to each SafePoint at a backward branch.
 432   // They were inserted during parsing (see add_safepoint()) to make infinite
 433   // loops without calls or exceptions visible to root, i.e., useful.
 434   Node *root = C->root();
 435   if( root != NULL ) {
 436     for( uint i = root->req(); i < root->len(); ++i ) {
 437       Node *n = root->in(i);
 438       if( n != NULL && n->is_SafePoint() ) {
 439         root->rm_prec(i);
 440         --i;
 441       }
 442     }
 443   }
 444 }
 445 
 446 
 447 //=============================================================================
 448 //------------------------------PhaseTransform---------------------------------
 449 PhaseTransform::PhaseTransform( PhaseNumber pnum ) : Phase(pnum),
 450   _arena(Thread::current()->resource_area()),
 451   _nodes(_arena),
 452   _types(_arena)
 453 {
 454   init_con_caches();
 455 #ifndef PRODUCT
 456   clear_progress();
 457   clear_transforms();
 458   set_allow_progress(true);
 459 #endif
 460   // Force allocation for currently existing nodes
 461   _types.map(C->unique(), NULL);
 462 }
 463 
 464 //------------------------------PhaseTransform---------------------------------
 465 PhaseTransform::PhaseTransform( Arena *arena, PhaseNumber pnum ) : Phase(pnum),
 466   _arena(arena),
 467   _nodes(arena),
 468   _types(arena)
 469 {
 470   init_con_caches();
 471 #ifndef PRODUCT
 472   clear_progress();
 473   clear_transforms();
 474   set_allow_progress(true);
 475 #endif
 476   // Force allocation for currently existing nodes
 477   _types.map(C->unique(), NULL);
 478 }
 479 
 480 //------------------------------PhaseTransform---------------------------------
 481 // Initialize with previously generated type information
 482 PhaseTransform::PhaseTransform( PhaseTransform *pt, PhaseNumber pnum ) : Phase(pnum),
 483   _arena(pt->_arena),
 484   _nodes(pt->_nodes),
 485   _types(pt->_types)
 486 {
 487   init_con_caches();
 488 #ifndef PRODUCT
 489   clear_progress();
 490   clear_transforms();
 491   set_allow_progress(true);
 492 #endif
 493 }
 494 
 495 void PhaseTransform::init_con_caches() {
 496   memset(_icons,0,sizeof(_icons));
 497   memset(_lcons,0,sizeof(_lcons));
 498   memset(_zcons,0,sizeof(_zcons));
 499 }
 500 
 501 
 502 //--------------------------------find_int_type--------------------------------
 503 const TypeInt* PhaseTransform::find_int_type(Node* n) {
 504   if (n == NULL)  return NULL;
 505   // Call type_or_null(n) to determine node's type since we might be in
 506   // parse phase and call n->Value() may return wrong type.
 507   // (For example, a phi node at the beginning of loop parsing is not ready.)
 508   const Type* t = type_or_null(n);
 509   if (t == NULL)  return NULL;
 510   return t->isa_int();
 511 }
 512 
 513 
 514 //-------------------------------find_long_type--------------------------------
 515 const TypeLong* PhaseTransform::find_long_type(Node* n) {
 516   if (n == NULL)  return NULL;
 517   // (See comment above on type_or_null.)
 518   const Type* t = type_or_null(n);
 519   if (t == NULL)  return NULL;
 520   return t->isa_long();
 521 }
 522 
 523 
 524 #ifndef PRODUCT
 525 void PhaseTransform::dump_old2new_map() const {
 526   _nodes.dump();
 527 }
 528 
 529 void PhaseTransform::dump_new( uint nidx ) const {
 530   for( uint i=0; i<_nodes.Size(); i++ )
 531     if( _nodes[i] && _nodes[i]->_idx == nidx ) {
 532       _nodes[i]->dump();
 533       tty->cr();
 534       tty->print_cr("Old index= %d",i);
 535       return;
 536     }
 537   tty->print_cr("Node %d not found in the new indices", nidx);
 538 }
 539 
 540 //------------------------------dump_types-------------------------------------
 541 void PhaseTransform::dump_types( ) const {
 542   _types.dump();
 543 }
 544 
 545 //------------------------------dump_nodes_and_types---------------------------
 546 void PhaseTransform::dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl) {
 547   VectorSet visited(Thread::current()->resource_area());
 548   dump_nodes_and_types_recur( root, depth, only_ctrl, visited );
 549 }
 550 
 551 //------------------------------dump_nodes_and_types_recur---------------------
 552 void PhaseTransform::dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited) {
 553   if( !n ) return;
 554   if( depth == 0 ) return;
 555   if( visited.test_set(n->_idx) ) return;
 556   for( uint i=0; i<n->len(); i++ ) {
 557     if( only_ctrl && !(n->is_Region()) && i != TypeFunc::Control ) continue;
 558     dump_nodes_and_types_recur( n->in(i), depth-1, only_ctrl, visited );
 559   }
 560   n->dump();
 561   if (type_or_null(n) != NULL) {
 562     tty->print("      "); type(n)->dump(); tty->cr();
 563   }
 564 }
 565 
 566 #endif
 567 
 568 
 569 //=============================================================================
 570 //------------------------------PhaseValues------------------------------------
 571 // Set minimum table size to "255"
 572 PhaseValues::PhaseValues( Arena *arena, uint est_max_size ) : PhaseTransform(arena, GVN), _table(arena, est_max_size) {
 573   NOT_PRODUCT( clear_new_values(); )
 574 }
 575 
 576 //------------------------------PhaseValues------------------------------------
 577 // Set minimum table size to "255"
 578 PhaseValues::PhaseValues( PhaseValues *ptv ) : PhaseTransform( ptv, GVN ),
 579   _table(&ptv->_table) {
 580   NOT_PRODUCT( clear_new_values(); )
 581 }
 582 
 583 //------------------------------PhaseValues------------------------------------
 584 // Used by +VerifyOpto.  Clear out hash table but copy _types array.
 585 PhaseValues::PhaseValues( PhaseValues *ptv, const char *dummy ) : PhaseTransform( ptv, GVN ),
 586   _table(ptv->arena(),ptv->_table.size()) {
 587   NOT_PRODUCT( clear_new_values(); )
 588 }
 589 
 590 //------------------------------~PhaseValues-----------------------------------
 591 #ifndef PRODUCT
 592 PhaseValues::~PhaseValues() {
 593   _table.dump();
 594 
 595   // Statistics for value progress and efficiency
 596   if( PrintCompilation && Verbose && WizardMode ) {
 597     tty->print("\n%sValues: %d nodes ---> %d/%d (%d)",
 598       is_IterGVN() ? "Iter" : "    ", C->unique(), made_progress(), made_transforms(), made_new_values());
 599     if( made_transforms() != 0 ) {
 600       tty->print_cr("  ratio %f", made_progress()/(float)made_transforms() );
 601     } else {
 602       tty->cr();
 603     }
 604   }
 605 }
 606 #endif
 607 
 608 //------------------------------makecon----------------------------------------
 609 ConNode* PhaseTransform::makecon(const Type *t) {
 610   assert(t->singleton(), "must be a constant");
 611   assert(!t->empty() || t == Type::TOP, "must not be vacuous range");
 612   switch (t->base()) {  // fast paths
 613   case Type::Half:
 614   case Type::Top:  return (ConNode*) C->top();
 615   case Type::Int:  return intcon( t->is_int()->get_con() );
 616   case Type::Long: return longcon( t->is_long()->get_con() );
 617   }
 618   if (t->is_zero_type())
 619     return zerocon(t->basic_type());
 620   return uncached_makecon(t);
 621 }
 622 
 623 //--------------------------uncached_makecon-----------------------------------
 624 // Make an idealized constant - one of ConINode, ConPNode, etc.
 625 ConNode* PhaseValues::uncached_makecon(const Type *t) {
 626   assert(t->singleton(), "must be a constant");
 627   ConNode* x = ConNode::make(t);
 628   ConNode* k = (ConNode*)hash_find_insert(x); // Value numbering
 629   if (k == NULL) {
 630     set_type(x, t);             // Missed, provide type mapping
 631     GrowableArray<Node_Notes*>* nna = C->node_note_array();
 632     if (nna != NULL) {
 633       Node_Notes* loc = C->locate_node_notes(nna, x->_idx, true);
 634       loc->clear(); // do not put debug info on constants
 635     }
 636   } else {
 637     x->destruct();              // Hit, destroy duplicate constant
 638     x = k;                      // use existing constant
 639   }
 640   return x;
 641 }
 642 
 643 //------------------------------intcon-----------------------------------------
 644 // Fast integer constant.  Same as "transform(new ConINode(TypeInt::make(i)))"
 645 ConINode* PhaseTransform::intcon(int i) {
 646   // Small integer?  Check cache! Check that cached node is not dead
 647   if (i >= _icon_min && i <= _icon_max) {
 648     ConINode* icon = _icons[i-_icon_min];
 649     if (icon != NULL && icon->in(TypeFunc::Control) != NULL)
 650       return icon;
 651   }
 652   ConINode* icon = (ConINode*) uncached_makecon(TypeInt::make(i));
 653   assert(icon->is_Con(), "");
 654   if (i >= _icon_min && i <= _icon_max)
 655     _icons[i-_icon_min] = icon;   // Cache small integers
 656   return icon;
 657 }
 658 
 659 //------------------------------longcon----------------------------------------
 660 // Fast long constant.
 661 ConLNode* PhaseTransform::longcon(jlong l) {
 662   // Small integer?  Check cache! Check that cached node is not dead
 663   if (l >= _lcon_min && l <= _lcon_max) {
 664     ConLNode* lcon = _lcons[l-_lcon_min];
 665     if (lcon != NULL && lcon->in(TypeFunc::Control) != NULL)
 666       return lcon;
 667   }
 668   ConLNode* lcon = (ConLNode*) uncached_makecon(TypeLong::make(l));
 669   assert(lcon->is_Con(), "");
 670   if (l >= _lcon_min && l <= _lcon_max)
 671     _lcons[l-_lcon_min] = lcon;      // Cache small integers
 672   return lcon;
 673 }
 674 
 675 //------------------------------zerocon-----------------------------------------
 676 // Fast zero or null constant. Same as "transform(ConNode::make(Type::get_zero_type(bt)))"
 677 ConNode* PhaseTransform::zerocon(BasicType bt) {
 678   assert((uint)bt <= _zcon_max, "domain check");
 679   ConNode* zcon = _zcons[bt];
 680   if (zcon != NULL && zcon->in(TypeFunc::Control) != NULL)
 681     return zcon;
 682   zcon = (ConNode*) uncached_makecon(Type::get_zero_type(bt));
 683   _zcons[bt] = zcon;
 684   return zcon;
 685 }
 686 
 687 
 688 
 689 //=============================================================================
 690 //------------------------------transform--------------------------------------
 691 // Return a node which computes the same function as this node, but in a
 692 // faster or cheaper fashion.
 693 Node *PhaseGVN::transform( Node *n ) {
 694   return transform_no_reclaim(n);
 695 }
 696 
 697 //------------------------------transform--------------------------------------
 698 // Return a node which computes the same function as this node, but
 699 // in a faster or cheaper fashion.
 700 Node *PhaseGVN::transform_no_reclaim( Node *n ) {
 701   NOT_PRODUCT( set_transforms(); )
 702 
 703   // Apply the Ideal call in a loop until it no longer applies
 704   Node *k = n;
 705   NOT_PRODUCT( uint loop_count = 0; )
 706   while( 1 ) {
 707     Node *i = k->Ideal(this, /*can_reshape=*/false);
 708     if( !i ) break;
 709     assert( i->_idx >= k->_idx, "Idealize should return new nodes, use Identity to return old nodes" );
 710     k = i;
 711     assert(loop_count++ < K, "infinite loop in PhaseGVN::transform");
 712   }
 713   NOT_PRODUCT( if( loop_count != 0 ) { set_progress(); } )
 714 
 715 
 716   // If brand new node, make space in type array.
 717   ensure_type_or_null(k);
 718 
 719   // Since I just called 'Value' to compute the set of run-time values
 720   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
 721   // cache Value.  Later requests for the local phase->type of this Node can
 722   // use the cached Value instead of suffering with 'bottom_type'.
 723   const Type *t = k->Value(this); // Get runtime Value set
 724   assert(t != NULL, "value sanity");
 725   if (type_or_null(k) != t) {
 726 #ifndef PRODUCT
 727     // Do not count initial visit to node as a transformation
 728     if (type_or_null(k) == NULL) {
 729       inc_new_values();
 730       set_progress();
 731     }
 732 #endif
 733     set_type(k, t);
 734     // If k is a TypeNode, capture any more-precise type permanently into Node
 735     k->raise_bottom_type(t);
 736   }
 737 
 738   if( t->singleton() && !k->is_Con() ) {
 739     NOT_PRODUCT( set_progress(); )
 740     return makecon(t);          // Turn into a constant
 741   }
 742 
 743   // Now check for Identities
 744   Node *i = k->Identity(this);  // Look for a nearby replacement
 745   if( i != k ) {                // Found? Return replacement!
 746     NOT_PRODUCT( set_progress(); )
 747     return i;
 748   }
 749 
 750   // Global Value Numbering
 751   i = hash_find_insert(k);      // Insert if new
 752   if( i && (i != k) ) {
 753     // Return the pre-existing node
 754     NOT_PRODUCT( set_progress(); )
 755     return i;
 756   }
 757 
 758   // Return Idealized original
 759   return k;
 760 }
 761 
 762 #ifdef ASSERT
 763 //------------------------------dead_loop_check--------------------------------
 764 // Check for a simple dead loop when a data node references itself directly
 765 // or through an other data node excluding cons and phis.
 766 void PhaseGVN::dead_loop_check( Node *n ) {
 767   // Phi may reference itself in a loop
 768   if (n != NULL && !n->is_dead_loop_safe() && !n->is_CFG()) {
 769     // Do 2 levels check and only data inputs.
 770     bool no_dead_loop = true;
 771     uint cnt = n->req();
 772     for (uint i = 1; i < cnt && no_dead_loop; i++) {
 773       Node *in = n->in(i);
 774       if (in == n) {
 775         no_dead_loop = false;
 776       } else if (in != NULL && !in->is_dead_loop_safe()) {
 777         uint icnt = in->req();
 778         for (uint j = 1; j < icnt && no_dead_loop; j++) {
 779           if (in->in(j) == n || in->in(j) == in)
 780             no_dead_loop = false;
 781         }
 782       }
 783     }
 784     if (!no_dead_loop) n->dump(3);
 785     assert(no_dead_loop, "dead loop detected");
 786   }
 787 }
 788 #endif
 789 
 790 //=============================================================================
 791 //------------------------------PhaseIterGVN-----------------------------------
 792 // Initialize hash table to fresh and clean for +VerifyOpto
 793 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn, const char *dummy ) : PhaseGVN(igvn,dummy), _worklist( ),
 794                                                                       _stack(C->unique() >> 1),
 795                                                                       _delay_transform(false) {
 796 }
 797 
 798 //------------------------------PhaseIterGVN-----------------------------------
 799 // Initialize with previous PhaseIterGVN info; used by PhaseCCP
 800 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn ) : PhaseGVN(igvn),
 801                                                    _worklist( igvn->_worklist ),
 802                                                    _stack( igvn->_stack ),
 803                                                    _delay_transform(igvn->_delay_transform)
 804 {
 805 }
 806 
 807 //------------------------------PhaseIterGVN-----------------------------------
 808 // Initialize with previous PhaseGVN info from Parser
 809 PhaseIterGVN::PhaseIterGVN( PhaseGVN *gvn ) : PhaseGVN(gvn),
 810                                               _worklist(*C->for_igvn()),
 811                                               _stack(C->unique() >> 1),
 812                                               _delay_transform(false)
 813 {
 814   uint max;
 815 
 816   // Dead nodes in the hash table inherited from GVN were not treated as
 817   // roots during def-use info creation; hence they represent an invisible
 818   // use.  Clear them out.
 819   max = _table.size();
 820   for( uint i = 0; i < max; ++i ) {
 821     Node *n = _table.at(i);
 822     if(n != NULL && n != _table.sentinel() && n->outcnt() == 0) {
 823       if( n->is_top() ) continue;
 824       assert( false, "Parse::remove_useless_nodes missed this node");
 825       hash_delete(n);
 826     }
 827   }
 828 
 829   // Any Phis or Regions on the worklist probably had uses that could not
 830   // make more progress because the uses were made while the Phis and Regions
 831   // were in half-built states.  Put all uses of Phis and Regions on worklist.
 832   max = _worklist.size();
 833   for( uint j = 0; j < max; j++ ) {
 834     Node *n = _worklist.at(j);
 835     uint uop = n->Opcode();
 836     if( uop == Op_Phi || uop == Op_Region ||
 837         n->is_Type() ||
 838         n->is_Mem() )
 839       add_users_to_worklist(n);
 840   }
 841 }
 842 
 843 /**
 844  * Initialize worklist for each node.
 845  */
 846 void PhaseIterGVN::init_worklist(Node* first) {
 847   Unique_Node_List to_process;
 848   to_process.push(first);
 849 
 850   while (to_process.size() > 0) {
 851     Node* n = to_process.pop();
 852     if (!_worklist.member(n)) {
 853       _worklist.push(n);
 854 
 855       uint cnt = n->req();
 856       for(uint i = 0; i < cnt; i++) {
 857         Node* m = n->in(i);
 858         if (m != NULL) {
 859           to_process.push(m);
 860         }
 861       }
 862     }
 863   }
 864 }
 865 
 866 #ifndef PRODUCT
 867 void PhaseIterGVN::verify_step(Node* n) {
 868   if (VerifyIterativeGVN) {
 869     _verify_window[_verify_counter % _verify_window_size] = n;
 870     ++_verify_counter;
 871     ResourceMark rm;
 872     ResourceArea* area = Thread::current()->resource_area();
 873     VectorSet old_space(area), new_space(area);
 874     if (C->unique() < 1000 ||
 875         0 == _verify_counter % (C->unique() < 10000 ? 10 : 100)) {
 876       ++_verify_full_passes;
 877       Node::verify_recur(C->root(), -1, old_space, new_space);
 878     }
 879     const int verify_depth = 4;
 880     for ( int i = 0; i < _verify_window_size; i++ ) {
 881       Node* n = _verify_window[i];
 882       if ( n == NULL )  continue;
 883       if( n->in(0) == NodeSentinel ) {  // xform_idom
 884         _verify_window[i] = n->in(1);
 885         --i; continue;
 886       }
 887       // Typical fanout is 1-2, so this call visits about 6 nodes.
 888       Node::verify_recur(n, verify_depth, old_space, new_space);
 889     }
 890   }
 891 }
 892 
 893 void PhaseIterGVN::trace_PhaseIterGVN(Node* n, Node* nn, const Type* oldtype) {
 894   if (TraceIterativeGVN) {
 895     uint wlsize = _worklist.size();
 896     const Type* newtype = type_or_null(n);
 897     if (nn != n) {
 898       // print old node
 899       tty->print("< ");
 900       if (oldtype != newtype && oldtype != NULL) {
 901         oldtype->dump();
 902       }
 903       do { tty->print("\t"); } while (tty->position() < 16);
 904       tty->print("<");
 905       n->dump();
 906     }
 907     if (oldtype != newtype || nn != n) {
 908       // print new node and/or new type
 909       if (oldtype == NULL) {
 910         tty->print("* ");
 911       } else if (nn != n) {
 912         tty->print("> ");
 913       } else {
 914         tty->print("= ");
 915       }
 916       if (newtype == NULL) {
 917         tty->print("null");
 918       } else {
 919         newtype->dump();
 920       }
 921       do { tty->print("\t"); } while (tty->position() < 16);
 922       nn->dump();
 923     }
 924     if (Verbose && wlsize < _worklist.size()) {
 925       tty->print("  Push {");
 926       while (wlsize != _worklist.size()) {
 927         Node* pushed = _worklist.at(wlsize++);
 928         tty->print(" %d", pushed->_idx);
 929       }
 930       tty->print_cr(" }");
 931     }
 932     if (nn != n) {
 933       // ignore n, it might be subsumed
 934       verify_step((Node*) NULL);
 935     }
 936   }
 937 }
 938 
 939 void PhaseIterGVN::init_verifyPhaseIterGVN() {
 940   _verify_counter = 0;
 941   _verify_full_passes = 0;
 942   for (int i = 0; i < _verify_window_size; i++) {
 943     _verify_window[i] = NULL;
 944   }
 945 #ifdef ASSERT
 946   // Verify that all modified nodes are on _worklist
 947   Unique_Node_List* modified_list = C->modified_nodes();
 948   while (modified_list != NULL && modified_list->size()) {
 949     Node* n = modified_list->pop();
 950     if (n->outcnt() != 0 && !n->is_Con() && !_worklist.member(n)) {
 951       n->dump();
 952       assert(false, "modified node is not on IGVN._worklist");
 953     }
 954   }
 955 #endif
 956 }
 957 
 958 void PhaseIterGVN::verify_PhaseIterGVN() {
 959 #ifdef ASSERT
 960   // Verify nodes with changed inputs.
 961   Unique_Node_List* modified_list = C->modified_nodes();
 962   while (modified_list != NULL && modified_list->size()) {
 963     Node* n = modified_list->pop();
 964     if (n->outcnt() != 0 && !n->is_Con()) { // skip dead and Con nodes
 965       n->dump();
 966       assert(false, "modified node was not processed by IGVN.transform_old()");
 967     }
 968   }
 969 #endif
 970 
 971   C->verify_graph_edges();
 972   if( VerifyOpto && allow_progress() ) {
 973     // Must turn off allow_progress to enable assert and break recursion
 974     C->root()->verify();
 975     { // Check if any progress was missed using IterGVN
 976       // Def-Use info enables transformations not attempted in wash-pass
 977       // e.g. Region/Phi cleanup, ...
 978       // Null-check elision -- may not have reached fixpoint
 979       //                       do not propagate to dominated nodes
 980       ResourceMark rm;
 981       PhaseIterGVN igvn2(this,"Verify"); // Fresh and clean!
 982       // Fill worklist completely
 983       igvn2.init_worklist(C->root());
 984 
 985       igvn2.set_allow_progress(false);
 986       igvn2.optimize();
 987       igvn2.set_allow_progress(true);
 988     }
 989   }
 990   if (VerifyIterativeGVN && PrintOpto) {
 991     if (_verify_counter == _verify_full_passes) {
 992       tty->print_cr("VerifyIterativeGVN: %d transforms and verify passes",
 993                     (int) _verify_full_passes);
 994     } else {
 995       tty->print_cr("VerifyIterativeGVN: %d transforms, %d full verify passes",
 996                   (int) _verify_counter, (int) _verify_full_passes);
 997     }
 998   }
 999 
1000 #ifdef ASSERT
1001   while (modified_list->size()) {
1002     Node* n = modified_list->pop();
1003     n->dump();
1004     assert(false, "VerifyIterativeGVN: new modified node was added");
1005   }
1006 #endif
1007 }
1008 #endif /* PRODUCT */
1009 
1010 #ifdef ASSERT
1011 /**
1012  * Dumps information that can help to debug the problem. A debug
1013  * build fails with an assert.
1014  */
1015 void PhaseIterGVN::dump_infinite_loop_info(Node* n) {
1016   n->dump(4);
1017   _worklist.dump();
1018   assert(false, "infinite loop in PhaseIterGVN::optimize");
1019 }
1020 
1021 /**
1022  * Prints out information about IGVN if the 'verbose' option is used.
1023  */
1024 void PhaseIterGVN::trace_PhaseIterGVN_verbose(Node* n, int num_processed) {
1025   if (TraceIterativeGVN && Verbose) {
1026     tty->print("  Pop ");
1027     n->dump();
1028     if ((num_processed % 100) == 0) {
1029       _worklist.print_set();
1030     }
1031   }
1032 }
1033 #endif /* ASSERT */
1034 
1035 void PhaseIterGVN::optimize() {
1036   DEBUG_ONLY(uint num_processed  = 0;)
1037   NOT_PRODUCT(init_verifyPhaseIterGVN();)
1038 
1039   uint loop_count = 0;
1040   // Pull from worklist and transform the node. If the node has changed,
1041   // update edge info and put uses on worklist.
1042   while(_worklist.size()) {
1043     if (C->check_node_count(NodeLimitFudgeFactor * 2, "Out of nodes")) {
1044       return;
1045     }
1046     Node* n  = _worklist.pop();
1047     if (++loop_count >= K * C->live_nodes()) {
1048       DEBUG_ONLY(dump_infinite_loop_info(n);)
1049       C->record_method_not_compilable("infinite loop in PhaseIterGVN::optimize");
1050       return;
1051     }
1052     DEBUG_ONLY(trace_PhaseIterGVN_verbose(n, num_processed++);)
1053     if (n->outcnt() != 0) {
1054       NOT_PRODUCT(const Type* oldtype = type_or_null(n));
1055       // Do the transformation
1056       Node* nn = transform_old(n);
1057       NOT_PRODUCT(trace_PhaseIterGVN(n, nn, oldtype);)
1058     } else if (!n->is_top()) {
1059       remove_dead_node(n);
1060     }
1061   }
1062   NOT_PRODUCT(verify_PhaseIterGVN();)
1063 }
1064 
1065 
1066 /**
1067  * Register a new node with the optimizer.  Update the types array, the def-use
1068  * info.  Put on worklist.
1069  */
1070 Node* PhaseIterGVN::register_new_node_with_optimizer(Node* n, Node* orig) {
1071   set_type_bottom(n);
1072   _worklist.push(n);
1073   if (orig != NULL)  C->copy_node_notes_to(n, orig);
1074   return n;
1075 }
1076 
1077 //------------------------------transform--------------------------------------
1078 // Non-recursive: idealize Node 'n' with respect to its inputs and its value
1079 Node *PhaseIterGVN::transform( Node *n ) {
1080   if (_delay_transform) {
1081     // Register the node but don't optimize for now
1082     register_new_node_with_optimizer(n);
1083     return n;
1084   }
1085 
1086   // If brand new node, make space in type array, and give it a type.
1087   ensure_type_or_null(n);
1088   if (type_or_null(n) == NULL) {
1089     set_type_bottom(n);
1090   }
1091 
1092   return transform_old(n);
1093 }
1094 
1095 Node *PhaseIterGVN::transform_old(Node* n) {
1096   DEBUG_ONLY(uint loop_count = 0;);
1097   NOT_PRODUCT(set_transforms());
1098 
1099   // Remove 'n' from hash table in case it gets modified
1100   _table.hash_delete(n);
1101   if (VerifyIterativeGVN) {
1102    assert(!_table.find_index(n->_idx), "found duplicate entry in table");
1103   }
1104 
1105   // Apply the Ideal call in a loop until it no longer applies
1106   Node* k = n;
1107   DEBUG_ONLY(dead_loop_check(k);)
1108   DEBUG_ONLY(bool is_new = (k->outcnt() == 0);)
1109   C->remove_modified_node(k);
1110   Node* i = k->Ideal(this, /*can_reshape=*/true);
1111   assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes");
1112 #ifndef PRODUCT
1113   verify_step(k);
1114   if (i && VerifyOpto ) {
1115     if (!allow_progress()) {
1116       if (i->is_Add() && (i->outcnt() == 1)) {
1117         // Switched input to left side because this is the only use
1118       } else if (i->is_If() && (i->in(0) == NULL)) {
1119         // This IF is dead because it is dominated by an equivalent IF When
1120         // dominating if changed, info is not propagated sparsely to 'this'
1121         // Propagating this info further will spuriously identify other
1122         // progress.
1123         return i;
1124       } else
1125         set_progress();
1126     } else {
1127       set_progress();
1128     }
1129   }
1130 #endif
1131 
1132   while (i != NULL) {
1133 #ifdef ASSERT
1134     if (loop_count >= K) {
1135       dump_infinite_loop_info(i);
1136     }
1137     loop_count++;
1138 #endif
1139     assert((i->_idx >= k->_idx) || i->is_top(), "Idealize should return new nodes, use Identity to return old nodes");
1140     // Made a change; put users of original Node on worklist
1141     add_users_to_worklist(k);
1142     // Replacing root of transform tree?
1143     if (k != i) {
1144       // Make users of old Node now use new.
1145       subsume_node(k, i);
1146       k = i;
1147     }
1148     DEBUG_ONLY(dead_loop_check(k);)
1149     // Try idealizing again
1150     DEBUG_ONLY(is_new = (k->outcnt() == 0);)
1151     C->remove_modified_node(k);
1152     i = k->Ideal(this, /*can_reshape=*/true);
1153     assert(i != k || is_new || (i->outcnt() > 0), "don't return dead nodes");
1154 #ifndef PRODUCT
1155     verify_step(k);
1156     if (i && VerifyOpto) {
1157       set_progress();
1158     }
1159 #endif
1160   }
1161 
1162   // If brand new node, make space in type array.
1163   ensure_type_or_null(k);
1164 
1165   // See what kind of values 'k' takes on at runtime
1166   const Type* t = k->Value(this);
1167   assert(t != NULL, "value sanity");
1168 
1169   // Since I just called 'Value' to compute the set of run-time values
1170   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
1171   // cache Value.  Later requests for the local phase->type of this Node can
1172   // use the cached Value instead of suffering with 'bottom_type'.
1173   if (type_or_null(k) != t) {
1174 #ifndef PRODUCT
1175     inc_new_values();
1176     set_progress();
1177 #endif
1178     set_type(k, t);
1179     // If k is a TypeNode, capture any more-precise type permanently into Node
1180     k->raise_bottom_type(t);
1181     // Move users of node to worklist
1182     add_users_to_worklist(k);
1183   }
1184   // If 'k' computes a constant, replace it with a constant
1185   if (t->singleton() && !k->is_Con()) {
1186     NOT_PRODUCT(set_progress();)
1187     Node* con = makecon(t);     // Make a constant
1188     add_users_to_worklist(k);
1189     subsume_node(k, con);       // Everybody using k now uses con
1190     return con;
1191   }
1192 
1193   // Now check for Identities
1194   i = k->Identity(this);      // Look for a nearby replacement
1195   if (i != k) {                // Found? Return replacement!
1196     NOT_PRODUCT(set_progress();)
1197     add_users_to_worklist(k);
1198     subsume_node(k, i);       // Everybody using k now uses i
1199     return i;
1200   }
1201 
1202   // Global Value Numbering
1203   i = hash_find_insert(k);      // Check for pre-existing node
1204   if (i && (i != k)) {
1205     // Return the pre-existing node if it isn't dead
1206     NOT_PRODUCT(set_progress();)
1207     add_users_to_worklist(k);
1208     subsume_node(k, i);       // Everybody using k now uses i
1209     return i;
1210   }
1211 
1212   // Return Idealized original
1213   return k;
1214 }
1215 
1216 //---------------------------------saturate------------------------------------
1217 const Type* PhaseIterGVN::saturate(const Type* new_type, const Type* old_type,
1218                                    const Type* limit_type) const {
1219   return new_type->narrow(old_type);
1220 }
1221 
1222 //------------------------------remove_globally_dead_node----------------------
1223 // Kill a globally dead Node.  All uses are also globally dead and are
1224 // aggressively trimmed.
1225 void PhaseIterGVN::remove_globally_dead_node( Node *dead ) {
1226   enum DeleteProgress {
1227     PROCESS_INPUTS,
1228     PROCESS_OUTPUTS
1229   };
1230   assert(_stack.is_empty(), "not empty");
1231   _stack.push(dead, PROCESS_INPUTS);
1232 
1233   while (_stack.is_nonempty()) {
1234     dead = _stack.node();
1235     uint progress_state = _stack.index();
1236     assert(dead != C->root(), "killing root, eh?");
1237     assert(!dead->is_top(), "add check for top when pushing");
1238     NOT_PRODUCT( set_progress(); )
1239     if (progress_state == PROCESS_INPUTS) {
1240       // After following inputs, continue to outputs
1241       _stack.set_index(PROCESS_OUTPUTS);
1242       if (!dead->is_Con()) { // Don't kill cons but uses
1243         bool recurse = false;
1244         // Remove from hash table
1245         _table.hash_delete( dead );
1246         // Smash all inputs to 'dead', isolating him completely
1247         for (uint i = 0; i < dead->req(); i++) {
1248           Node *in = dead->in(i);
1249           if (in != NULL && in != C->top()) {  // Points to something?
1250             int nrep = dead->replace_edge(in, NULL);  // Kill edges
1251             assert((nrep > 0), "sanity");
1252             if (in->outcnt() == 0) { // Made input go dead?
1253               _stack.push(in, PROCESS_INPUTS); // Recursively remove
1254               recurse = true;
1255             } else if (in->outcnt() == 1 &&
1256                        in->has_special_unique_user()) {
1257               _worklist.push(in->unique_out());
1258             } else if (in->outcnt() <= 2 && dead->is_Phi()) {
1259               if (in->Opcode() == Op_Region) {
1260                 _worklist.push(in);
1261               } else if (in->is_Store()) {
1262                 DUIterator_Fast imax, i = in->fast_outs(imax);
1263                 _worklist.push(in->fast_out(i));
1264                 i++;
1265                 if (in->outcnt() == 2) {
1266                   _worklist.push(in->fast_out(i));
1267                   i++;
1268                 }
1269                 assert(!(i < imax), "sanity");
1270               }
1271             }
1272             if (ReduceFieldZeroing && dead->is_Load() && i == MemNode::Memory &&
1273                 in->is_Proj() && in->in(0) != NULL && in->in(0)->is_Initialize()) {
1274               // A Load that directly follows an InitializeNode is
1275               // going away. The Stores that follow are candidates
1276               // again to be captured by the InitializeNode.
1277               for (DUIterator_Fast jmax, j = in->fast_outs(jmax); j < jmax; j++) {
1278                 Node *n = in->fast_out(j);
1279                 if (n->is_Store()) {
1280                   _worklist.push(n);
1281                 }
1282               }
1283             }
1284           } // if (in != NULL && in != C->top())
1285         } // for (uint i = 0; i < dead->req(); i++)
1286         if (recurse) {
1287           continue;
1288         }
1289       } // if (!dead->is_Con())
1290     } // if (progress_state == PROCESS_INPUTS)
1291 
1292     // Aggressively kill globally dead uses
1293     // (Rather than pushing all the outs at once, we push one at a time,
1294     // plus the parent to resume later, because of the indefinite number
1295     // of edge deletions per loop trip.)
1296     if (dead->outcnt() > 0) {
1297       // Recursively remove output edges
1298       _stack.push(dead->raw_out(0), PROCESS_INPUTS);
1299     } else {
1300       // Finished disconnecting all input and output edges.
1301       _stack.pop();
1302       // Remove dead node from iterative worklist
1303       _worklist.remove(dead);
1304       C->remove_modified_node(dead);
1305       // Constant node that has no out-edges and has only one in-edge from
1306       // root is usually dead. However, sometimes reshaping walk makes
1307       // it reachable by adding use edges. So, we will NOT count Con nodes
1308       // as dead to be conservative about the dead node count at any
1309       // given time.
1310       if (!dead->is_Con()) {
1311         C->record_dead_node(dead->_idx);
1312       }
1313       if (dead->is_macro()) {
1314         C->remove_macro_node(dead);
1315       }
1316       if (dead->is_expensive()) {
1317         C->remove_expensive_node(dead);
1318       }
1319     }
1320   } // while (_stack.is_nonempty())
1321 }
1322 
1323 //------------------------------subsume_node-----------------------------------
1324 // Remove users from node 'old' and add them to node 'nn'.
1325 void PhaseIterGVN::subsume_node( Node *old, Node *nn ) {
1326   assert( old != hash_find(old), "should already been removed" );
1327   assert( old != C->top(), "cannot subsume top node");
1328   // Copy debug or profile information to the new version:
1329   C->copy_node_notes_to(nn, old);
1330   // Move users of node 'old' to node 'nn'
1331   for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) {
1332     Node* use = old->last_out(i);  // for each use...
1333     // use might need re-hashing (but it won't if it's a new node)
1334     rehash_node_delayed(use);
1335     // Update use-def info as well
1336     // We remove all occurrences of old within use->in,
1337     // so as to avoid rehashing any node more than once.
1338     // The hash table probe swamps any outer loop overhead.
1339     uint num_edges = 0;
1340     for (uint jmax = use->len(), j = 0; j < jmax; j++) {
1341       if (use->in(j) == old) {
1342         use->set_req(j, nn);
1343         ++num_edges;
1344       }
1345     }
1346     i -= num_edges;    // we deleted 1 or more copies of this edge
1347   }
1348 
1349   // Smash all inputs to 'old', isolating him completely
1350   Node *temp = new Node(1);
1351   temp->init_req(0,nn);     // Add a use to nn to prevent him from dying
1352   remove_dead_node( old );
1353   temp->del_req(0);         // Yank bogus edge
1354 #ifndef PRODUCT
1355   if( VerifyIterativeGVN ) {
1356     for ( int i = 0; i < _verify_window_size; i++ ) {
1357       if ( _verify_window[i] == old )
1358         _verify_window[i] = nn;
1359     }
1360   }
1361 #endif
1362   _worklist.remove(temp);   // this can be necessary
1363   temp->destruct();         // reuse the _idx of this little guy
1364 }
1365 
1366 //------------------------------add_users_to_worklist--------------------------
1367 void PhaseIterGVN::add_users_to_worklist0( Node *n ) {
1368   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1369     _worklist.push(n->fast_out(i));  // Push on worklist
1370   }
1371 }
1372 
1373 void PhaseIterGVN::add_users_to_worklist( Node *n ) {
1374   add_users_to_worklist0(n);
1375 
1376   // Move users of node to worklist
1377   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1378     Node* use = n->fast_out(i); // Get use
1379 
1380     if( use->is_Multi() ||      // Multi-definer?  Push projs on worklist
1381         use->is_Store() )       // Enable store/load same address
1382       add_users_to_worklist0(use);
1383 
1384     // If we changed the receiver type to a call, we need to revisit
1385     // the Catch following the call.  It's looking for a non-NULL
1386     // receiver to know when to enable the regular fall-through path
1387     // in addition to the NullPtrException path.
1388     if (use->is_CallDynamicJava() && n == use->in(TypeFunc::Parms)) {
1389       Node* p = use->as_CallDynamicJava()->proj_out(TypeFunc::Control);
1390       if (p != NULL) {
1391         add_users_to_worklist0(p);
1392       }
1393     }
1394 
1395     if( use->is_Cmp() ) {       // Enable CMP/BOOL optimization
1396       add_users_to_worklist(use); // Put Bool on worklist
1397       // Look for the 'is_x2logic' pattern: "x ? : 0 : 1" and put the
1398       // phi merging either 0 or 1 onto the worklist
1399       if (use->outcnt() > 0) {
1400         Node* bol = use->raw_out(0);
1401         if (bol->outcnt() > 0) {
1402           Node* iff = bol->raw_out(0);
1403           if (iff->outcnt() == 2) {
1404             Node* ifproj0 = iff->raw_out(0);
1405             Node* ifproj1 = iff->raw_out(1);
1406             if (ifproj0->outcnt() > 0 && ifproj1->outcnt() > 0) {
1407               Node* region0 = ifproj0->raw_out(0);
1408               Node* region1 = ifproj1->raw_out(0);
1409               if( region0 == region1 )
1410                 add_users_to_worklist0(region0);
1411             }
1412           }
1413         }
1414       }
1415     }
1416 
1417     uint use_op = use->Opcode();
1418     // If changed Cast input, check Phi users for simple cycles
1419     if( use->is_ConstraintCast() || use->is_CheckCastPP() ) {
1420       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1421         Node* u = use->fast_out(i2);
1422         if (u->is_Phi())
1423           _worklist.push(u);
1424       }
1425     }
1426     // If changed LShift inputs, check RShift users for useless sign-ext
1427     if( use_op == Op_LShiftI ) {
1428       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1429         Node* u = use->fast_out(i2);
1430         if (u->Opcode() == Op_RShiftI)
1431           _worklist.push(u);
1432       }
1433     }
1434     // If changed AddI/SubI inputs, check CmpU for range check optimization.
1435     if (use_op == Op_AddI || use_op == Op_SubI) {
1436       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1437         Node* u = use->fast_out(i2);
1438         if (u->is_Cmp() && (u->Opcode() == Op_CmpU)) {
1439           _worklist.push(u);
1440         }
1441       }
1442     }
1443     // If changed AddP inputs, check Stores for loop invariant
1444     if( use_op == Op_AddP ) {
1445       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1446         Node* u = use->fast_out(i2);
1447         if (u->is_Mem())
1448           _worklist.push(u);
1449       }
1450     }
1451     // If changed initialization activity, check dependent Stores
1452     if (use_op == Op_Allocate || use_op == Op_AllocateArray) {
1453       InitializeNode* init = use->as_Allocate()->initialization();
1454       if (init != NULL) {
1455         Node* imem = init->proj_out(TypeFunc::Memory);
1456         if (imem != NULL)  add_users_to_worklist0(imem);
1457       }
1458     }
1459     if (use_op == Op_Initialize) {
1460       Node* imem = use->as_Initialize()->proj_out(TypeFunc::Memory);
1461       if (imem != NULL)  add_users_to_worklist0(imem);
1462     }
1463   }
1464 }
1465 
1466 /**
1467  * Remove the speculative part of all types that we know of
1468  */
1469 void PhaseIterGVN::remove_speculative_types()  {
1470   assert(UseTypeSpeculation, "speculation is off");
1471   for (uint i = 0; i < _types.Size(); i++)  {
1472     const Type* t = _types.fast_lookup(i);
1473     if (t != NULL) {
1474       _types.map(i, t->remove_speculative());
1475     }
1476   }
1477   _table.check_no_speculative_types();
1478 }
1479 
1480 //=============================================================================
1481 #ifndef PRODUCT
1482 uint PhaseCCP::_total_invokes   = 0;
1483 uint PhaseCCP::_total_constants = 0;
1484 #endif
1485 //------------------------------PhaseCCP---------------------------------------
1486 // Conditional Constant Propagation, ala Wegman & Zadeck
1487 PhaseCCP::PhaseCCP( PhaseIterGVN *igvn ) : PhaseIterGVN(igvn) {
1488   NOT_PRODUCT( clear_constants(); )
1489   assert( _worklist.size() == 0, "" );
1490   // Clear out _nodes from IterGVN.  Must be clear to transform call.
1491   _nodes.clear();               // Clear out from IterGVN
1492   analyze();
1493 }
1494 
1495 #ifndef PRODUCT
1496 //------------------------------~PhaseCCP--------------------------------------
1497 PhaseCCP::~PhaseCCP() {
1498   inc_invokes();
1499   _total_constants += count_constants();
1500 }
1501 #endif
1502 
1503 
1504 #ifdef ASSERT
1505 static bool ccp_type_widens(const Type* t, const Type* t0) {
1506   assert(t->meet(t0) == t, "Not monotonic");
1507   switch (t->base() == t0->base() ? t->base() : Type::Top) {
1508   case Type::Int:
1509     assert(t0->isa_int()->_widen <= t->isa_int()->_widen, "widen increases");
1510     break;
1511   case Type::Long:
1512     assert(t0->isa_long()->_widen <= t->isa_long()->_widen, "widen increases");
1513     break;
1514   }
1515   return true;
1516 }
1517 #endif //ASSERT
1518 
1519 //------------------------------analyze----------------------------------------
1520 void PhaseCCP::analyze() {
1521   // Initialize all types to TOP, optimistic analysis
1522   for (int i = C->unique() - 1; i >= 0; i--)  {
1523     _types.map(i,Type::TOP);
1524   }
1525 
1526   // Push root onto worklist
1527   Unique_Node_List worklist;
1528   worklist.push(C->root());
1529 
1530   // Pull from worklist; compute new value; push changes out.
1531   // This loop is the meat of CCP.
1532   while( worklist.size() ) {
1533     Node *n = worklist.pop();
1534     const Type *t = n->Value(this);
1535     if (t != type(n)) {
1536       assert(ccp_type_widens(t, type(n)), "ccp type must widen");
1537 #ifndef PRODUCT
1538       if( TracePhaseCCP ) {
1539         t->dump();
1540         do { tty->print("\t"); } while (tty->position() < 16);
1541         n->dump();
1542       }
1543 #endif
1544       set_type(n, t);
1545       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1546         Node* m = n->fast_out(i);   // Get user
1547         if( m->is_Region() ) {  // New path to Region?  Must recheck Phis too
1548           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1549             Node* p = m->fast_out(i2); // Propagate changes to uses
1550             if( p->bottom_type() != type(p) ) // If not already bottomed out
1551               worklist.push(p); // Propagate change to user
1552           }
1553         }
1554         // If we changed the receiver type to a call, we need to revisit
1555         // the Catch following the call.  It's looking for a non-NULL
1556         // receiver to know when to enable the regular fall-through path
1557         // in addition to the NullPtrException path
1558         if (m->is_Call()) {
1559           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1560             Node* p = m->fast_out(i2);  // Propagate changes to uses
1561             if (p->is_Proj() && p->as_Proj()->_con == TypeFunc::Control && p->outcnt() == 1)
1562               worklist.push(p->unique_out());
1563           }
1564         }
1565         if( m->bottom_type() != type(m) ) // If not already bottomed out
1566           worklist.push(m);     // Propagate change to user
1567       }
1568     }
1569   }
1570 }
1571 
1572 //------------------------------do_transform-----------------------------------
1573 // Top level driver for the recursive transformer
1574 void PhaseCCP::do_transform() {
1575   // Correct leaves of new-space Nodes; they point to old-space.
1576   C->set_root( transform(C->root())->as_Root() );
1577   assert( C->top(),  "missing TOP node" );
1578   assert( C->root(), "missing root" );
1579 
1580   // Eagerly remove castPP nodes here. CastPP nodes might not be
1581   // removed in the subsequent IGVN phase if a node that changes
1582   // in(1) of a castPP is processed prior to the castPP node.
1583   for (uint i = 0; i < _worklist.size(); i++) {
1584     Node* n = _worklist.at(i);
1585 
1586     if (n->is_ConstraintCast()) {
1587       Node* nn = n->Identity(this);
1588       if (nn != n) {
1589         replace_node(n, nn);
1590         --i;
1591       }
1592     }
1593   }
1594 }
1595 
1596 //------------------------------transform--------------------------------------
1597 // Given a Node in old-space, clone him into new-space.
1598 // Convert any of his old-space children into new-space children.
1599 Node *PhaseCCP::transform( Node *n ) {
1600   Node *new_node = _nodes[n->_idx]; // Check for transformed node
1601   if( new_node != NULL )
1602     return new_node;                // Been there, done that, return old answer
1603   new_node = transform_once(n);     // Check for constant
1604   _nodes.map( n->_idx, new_node );  // Flag as having been cloned
1605 
1606   // Allocate stack of size _nodes.Size()/2 to avoid frequent realloc
1607   GrowableArray <Node *> trstack(C->unique() >> 1);
1608 
1609   trstack.push(new_node);           // Process children of cloned node
1610   while ( trstack.is_nonempty() ) {
1611     Node *clone = trstack.pop();
1612     uint cnt = clone->req();
1613     for( uint i = 0; i < cnt; i++ ) {          // For all inputs do
1614       Node *input = clone->in(i);
1615       if( input != NULL ) {                    // Ignore NULLs
1616         Node *new_input = _nodes[input->_idx]; // Check for cloned input node
1617         if( new_input == NULL ) {
1618           new_input = transform_once(input);   // Check for constant
1619           _nodes.map( input->_idx, new_input );// Flag as having been cloned
1620           trstack.push(new_input);
1621         }
1622         assert( new_input == clone->in(i), "insanity check");
1623       }
1624     }
1625   }
1626   return new_node;
1627 }
1628 
1629 
1630 //------------------------------transform_once---------------------------------
1631 // For PhaseCCP, transformation is IDENTITY unless Node computed a constant.
1632 Node *PhaseCCP::transform_once( Node *n ) {
1633   const Type *t = type(n);
1634   // Constant?  Use constant Node instead
1635   if( t->singleton() ) {
1636     Node *nn = n;               // Default is to return the original constant
1637     if( t == Type::TOP ) {
1638       // cache my top node on the Compile instance
1639       if( C->cached_top_node() == NULL || C->cached_top_node()->in(0) == NULL ) {
1640         C->set_cached_top_node(ConNode::make(Type::TOP));
1641         set_type(C->top(), Type::TOP);
1642       }
1643       nn = C->top();
1644     }
1645     if( !n->is_Con() ) {
1646       if( t != Type::TOP ) {
1647         nn = makecon(t);        // ConNode::make(t);
1648         NOT_PRODUCT( inc_constants(); )
1649       } else if( n->is_Region() ) { // Unreachable region
1650         // Note: nn == C->top()
1651         n->set_req(0, NULL);        // Cut selfreference
1652         // Eagerly remove dead phis to avoid phis copies creation.
1653         for (DUIterator i = n->outs(); n->has_out(i); i++) {
1654           Node* m = n->out(i);
1655           if( m->is_Phi() ) {
1656             assert(type(m) == Type::TOP, "Unreachable region should not have live phis.");
1657             replace_node(m, nn);
1658             --i; // deleted this phi; rescan starting with next position
1659           }
1660         }
1661       }
1662       replace_node(n,nn);       // Update DefUse edges for new constant
1663     }
1664     return nn;
1665   }
1666 
1667   // If x is a TypeNode, capture any more-precise type permanently into Node
1668   if (t != n->bottom_type()) {
1669     hash_delete(n);             // changing bottom type may force a rehash
1670     n->raise_bottom_type(t);
1671     _worklist.push(n);          // n re-enters the hash table via the worklist
1672   }
1673 
1674   // Idealize graph using DU info.  Must clone() into new-space.
1675   // DU info is generally used to show profitability, progress or safety
1676   // (but generally not needed for correctness).
1677   Node *nn = n->Ideal_DU_postCCP(this);
1678 
1679   // TEMPORARY fix to ensure that 2nd GVN pass eliminates NULL checks
1680   switch( n->Opcode() ) {
1681   case Op_FastLock:      // Revisit FastLocks for lock coarsening
1682   case Op_If:
1683   case Op_CountedLoopEnd:
1684   case Op_Region:
1685   case Op_Loop:
1686   case Op_CountedLoop:
1687   case Op_Conv2B:
1688   case Op_Opaque1:
1689   case Op_Opaque2:
1690     _worklist.push(n);
1691     break;
1692   default:
1693     break;
1694   }
1695   if( nn ) {
1696     _worklist.push(n);
1697     // Put users of 'n' onto worklist for second igvn transform
1698     add_users_to_worklist(n);
1699     return nn;
1700   }
1701 
1702   return  n;
1703 }
1704 
1705 //---------------------------------saturate------------------------------------
1706 const Type* PhaseCCP::saturate(const Type* new_type, const Type* old_type,
1707                                const Type* limit_type) const {
1708   const Type* wide_type = new_type->widen(old_type, limit_type);
1709   if (wide_type != new_type) {          // did we widen?
1710     // If so, we may have widened beyond the limit type.  Clip it back down.
1711     new_type = wide_type->filter(limit_type);
1712   }
1713   return new_type;
1714 }
1715 
1716 //------------------------------print_statistics-------------------------------
1717 #ifndef PRODUCT
1718 void PhaseCCP::print_statistics() {
1719   tty->print_cr("CCP: %d  constants found: %d", _total_invokes, _total_constants);
1720 }
1721 #endif
1722 
1723 
1724 //=============================================================================
1725 #ifndef PRODUCT
1726 uint PhasePeephole::_total_peepholes = 0;
1727 #endif
1728 //------------------------------PhasePeephole----------------------------------
1729 // Conditional Constant Propagation, ala Wegman & Zadeck
1730 PhasePeephole::PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg )
1731   : PhaseTransform(Peephole), _regalloc(regalloc), _cfg(cfg) {
1732   NOT_PRODUCT( clear_peepholes(); )
1733 }
1734 
1735 #ifndef PRODUCT
1736 //------------------------------~PhasePeephole---------------------------------
1737 PhasePeephole::~PhasePeephole() {
1738   _total_peepholes += count_peepholes();
1739 }
1740 #endif
1741 
1742 //------------------------------transform--------------------------------------
1743 Node *PhasePeephole::transform( Node *n ) {
1744   ShouldNotCallThis();
1745   return NULL;
1746 }
1747 
1748 //------------------------------do_transform-----------------------------------
1749 void PhasePeephole::do_transform() {
1750   bool method_name_not_printed = true;
1751 
1752   // Examine each basic block
1753   for (uint block_number = 1; block_number < _cfg.number_of_blocks(); ++block_number) {
1754     Block* block = _cfg.get_block(block_number);
1755     bool block_not_printed = true;
1756 
1757     // and each instruction within a block
1758     uint end_index = block->number_of_nodes();
1759     // block->end_idx() not valid after PhaseRegAlloc
1760     for( uint instruction_index = 1; instruction_index < end_index; ++instruction_index ) {
1761       Node     *n = block->get_node(instruction_index);
1762       if( n->is_Mach() ) {
1763         MachNode *m = n->as_Mach();
1764         int deleted_count = 0;
1765         // check for peephole opportunities
1766         MachNode *m2 = m->peephole(block, instruction_index, _regalloc, deleted_count);
1767         if( m2 != NULL ) {
1768 #ifndef PRODUCT
1769           if( PrintOptoPeephole ) {
1770             // Print method, first time only
1771             if( C->method() && method_name_not_printed ) {
1772               C->method()->print_short_name(); tty->cr();
1773               method_name_not_printed = false;
1774             }
1775             // Print this block
1776             if( Verbose && block_not_printed) {
1777               tty->print_cr("in block");
1778               block->dump();
1779               block_not_printed = false;
1780             }
1781             // Print instructions being deleted
1782             for( int i = (deleted_count - 1); i >= 0; --i ) {
1783               block->get_node(instruction_index-i)->as_Mach()->format(_regalloc); tty->cr();
1784             }
1785             tty->print_cr("replaced with");
1786             // Print new instruction
1787             m2->format(_regalloc);
1788             tty->print("\n\n");
1789           }
1790 #endif
1791           // Remove old nodes from basic block and update instruction_index
1792           // (old nodes still exist and may have edges pointing to them
1793           //  as register allocation info is stored in the allocator using
1794           //  the node index to live range mappings.)
1795           uint safe_instruction_index = (instruction_index - deleted_count);
1796           for( ; (instruction_index > safe_instruction_index); --instruction_index ) {
1797             block->remove_node( instruction_index );
1798           }
1799           // install new node after safe_instruction_index
1800           block->insert_node(m2, safe_instruction_index + 1);
1801           end_index = block->number_of_nodes() - 1; // Recompute new block size
1802           NOT_PRODUCT( inc_peepholes(); )
1803         }
1804       }
1805     }
1806   }
1807 }
1808 
1809 //------------------------------print_statistics-------------------------------
1810 #ifndef PRODUCT
1811 void PhasePeephole::print_statistics() {
1812   tty->print_cr("Peephole: peephole rules applied: %d",  _total_peepholes);
1813 }
1814 #endif
1815 
1816 
1817 //=============================================================================
1818 //------------------------------set_req_X--------------------------------------
1819 void Node::set_req_X( uint i, Node *n, PhaseIterGVN *igvn ) {
1820   assert( is_not_dead(n), "can not use dead node");
1821   assert( igvn->hash_find(this) != this, "Need to remove from hash before changing edges" );
1822   Node *old = in(i);
1823   set_req(i, n);
1824 
1825   // old goes dead?
1826   if( old ) {
1827     switch (old->outcnt()) {
1828     case 0:
1829       // Put into the worklist to kill later. We do not kill it now because the
1830       // recursive kill will delete the current node (this) if dead-loop exists
1831       if (!old->is_top())
1832         igvn->_worklist.push( old );
1833       break;
1834     case 1:
1835       if( old->is_Store() || old->has_special_unique_user() )
1836         igvn->add_users_to_worklist( old );
1837       break;
1838     case 2:
1839       if( old->is_Store() )
1840         igvn->add_users_to_worklist( old );
1841       if( old->Opcode() == Op_Region )
1842         igvn->_worklist.push(old);
1843       break;
1844     case 3:
1845       if( old->Opcode() == Op_Region ) {
1846         igvn->_worklist.push(old);
1847         igvn->add_users_to_worklist( old );
1848       }
1849       break;
1850     default:
1851       break;
1852     }
1853   }
1854 
1855 }
1856 
1857 //-------------------------------replace_by-----------------------------------
1858 // Using def-use info, replace one node for another.  Follow the def-use info
1859 // to all users of the OLD node.  Then make all uses point to the NEW node.
1860 void Node::replace_by(Node *new_node) {
1861   assert(!is_top(), "top node has no DU info");
1862   for (DUIterator_Last imin, i = last_outs(imin); i >= imin; ) {
1863     Node* use = last_out(i);
1864     uint uses_found = 0;
1865     for (uint j = 0; j < use->len(); j++) {
1866       if (use->in(j) == this) {
1867         if (j < use->req())
1868               use->set_req(j, new_node);
1869         else  use->set_prec(j, new_node);
1870         uses_found++;
1871       }
1872     }
1873     i -= uses_found;    // we deleted 1 or more copies of this edge
1874   }
1875 }
1876 
1877 //=============================================================================
1878 //-----------------------------------------------------------------------------
1879 void Type_Array::grow( uint i ) {
1880   if( !_max ) {
1881     _max = 1;
1882     _types = (const Type**)_a->Amalloc( _max * sizeof(Type*) );
1883     _types[0] = NULL;
1884   }
1885   uint old = _max;
1886   while( i >= _max ) _max <<= 1;        // Double to fit
1887   _types = (const Type**)_a->Arealloc( _types, old*sizeof(Type*),_max*sizeof(Type*));
1888   memset( &_types[old], 0, (_max-old)*sizeof(Type*) );
1889 }
1890 
1891 //------------------------------dump-------------------------------------------
1892 #ifndef PRODUCT
1893 void Type_Array::dump() const {
1894   uint max = Size();
1895   for( uint i = 0; i < max; i++ ) {
1896     if( _types[i] != NULL ) {
1897       tty->print("  %d\t== ", i); _types[i]->dump(); tty->cr();
1898     }
1899   }
1900 }
1901 #endif