1 /*
   2  * Copyright 1997-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 #include "incls/_precompiled.incl"
  26 #include "incls/_phaseX.cpp.incl"
  27 
  28 //=============================================================================
  29 #define NODE_HASH_MINIMUM_SIZE    255
  30 //------------------------------NodeHash---------------------------------------
  31 NodeHash::NodeHash(uint est_max_size) :
  32   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
  33   _a(Thread::current()->resource_area()),
  34   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) ), // (Node**)_a->Amalloc(_max * sizeof(Node*)) ),
  35   _inserts(0), _insert_limit( insert_limit() ),
  36   _look_probes(0), _lookup_hits(0), _lookup_misses(0),
  37   _total_insert_probes(0), _total_inserts(0),
  38   _insert_probes(0), _grows(0) {
  39   // _sentinel must be in the current node space
  40   _sentinel = new (Compile::current(), 1) ProjNode(NULL, TypeFunc::Control);
  41   memset(_table,0,sizeof(Node*)*_max);
  42 }
  43 
  44 //------------------------------NodeHash---------------------------------------
  45 NodeHash::NodeHash(Arena *arena, uint est_max_size) :
  46   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
  47   _a(arena),
  48   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) ),
  49   _inserts(0), _insert_limit( insert_limit() ),
  50   _look_probes(0), _lookup_hits(0), _lookup_misses(0),
  51   _delete_probes(0), _delete_hits(0), _delete_misses(0),
  52   _total_insert_probes(0), _total_inserts(0),
  53   _insert_probes(0), _grows(0) {
  54   // _sentinel must be in the current node space
  55   _sentinel = new (Compile::current(), 1) ProjNode(NULL, TypeFunc::Control);
  56   memset(_table,0,sizeof(Node*)*_max);
  57 }
  58 
  59 //------------------------------NodeHash---------------------------------------
  60 NodeHash::NodeHash(NodeHash *nh) {
  61   debug_only(_table = (Node**)badAddress);   // interact correctly w/ operator=
  62   // just copy in all the fields
  63   *this = *nh;
  64   // nh->_sentinel must be in the current node space
  65 }
  66 
  67 //------------------------------hash_find--------------------------------------
  68 // Find in hash table
  69 Node *NodeHash::hash_find( const Node *n ) {
  70   // ((Node*)n)->set_hash( n->hash() );
  71   uint hash = n->hash();
  72   if (hash == Node::NO_HASH) {
  73     debug_only( _lookup_misses++ );
  74     return NULL;
  75   }
  76   uint key = hash & (_max-1);
  77   uint stride = key | 0x01;
  78   debug_only( _look_probes++ );
  79   Node *k = _table[key];        // Get hashed value
  80   if( !k ) {                    // ?Miss?
  81     debug_only( _lookup_misses++ );
  82     return NULL;                // Miss!
  83   }
  84 
  85   int op = n->Opcode();
  86   uint req = n->req();
  87   while( 1 ) {                  // While probing hash table
  88     if( k->req() == req &&      // Same count of inputs
  89         k->Opcode() == op ) {   // Same Opcode
  90       for( uint i=0; i<req; i++ )
  91         if( n->in(i)!=k->in(i)) // Different inputs?
  92           goto collision;       // "goto" is a speed hack...
  93       if( n->cmp(*k) ) {        // Check for any special bits
  94         debug_only( _lookup_hits++ );
  95         return k;               // Hit!
  96       }
  97     }
  98   collision:
  99     debug_only( _look_probes++ );
 100     key = (key + stride/*7*/) & (_max-1); // Stride through table with relative prime
 101     k = _table[key];            // Get hashed value
 102     if( !k ) {                  // ?Miss?
 103       debug_only( _lookup_misses++ );
 104       return NULL;              // Miss!
 105     }
 106   }
 107   ShouldNotReachHere();
 108   return NULL;
 109 }
 110 
 111 //------------------------------hash_find_insert-------------------------------
 112 // Find in hash table, insert if not already present
 113 // Used to preserve unique entries in hash table
 114 Node *NodeHash::hash_find_insert( Node *n ) {
 115   // n->set_hash( );
 116   uint hash = n->hash();
 117   if (hash == Node::NO_HASH) {
 118     debug_only( _lookup_misses++ );
 119     return NULL;
 120   }
 121   uint key = hash & (_max-1);
 122   uint stride = key | 0x01;     // stride must be relatively prime to table siz
 123   uint first_sentinel = 0;      // replace a sentinel if seen.
 124   debug_only( _look_probes++ );
 125   Node *k = _table[key];        // Get hashed value
 126   if( !k ) {                    // ?Miss?
 127     debug_only( _lookup_misses++ );
 128     _table[key] = n;            // Insert into table!
 129     debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 130     check_grow();               // Grow table if insert hit limit
 131     return NULL;                // Miss!
 132   }
 133   else if( k == _sentinel ) {
 134     first_sentinel = key;      // Can insert here
 135   }
 136 
 137   int op = n->Opcode();
 138   uint req = n->req();
 139   while( 1 ) {                  // While probing hash table
 140     if( k->req() == req &&      // Same count of inputs
 141         k->Opcode() == op ) {   // Same Opcode
 142       for( uint i=0; i<req; i++ )
 143         if( n->in(i)!=k->in(i)) // Different inputs?
 144           goto collision;       // "goto" is a speed hack...
 145       if( n->cmp(*k) ) {        // Check for any special bits
 146         debug_only( _lookup_hits++ );
 147         return k;               // Hit!
 148       }
 149     }
 150   collision:
 151     debug_only( _look_probes++ );
 152     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
 153     k = _table[key];            // Get hashed value
 154     if( !k ) {                  // ?Miss?
 155       debug_only( _lookup_misses++ );
 156       key = (first_sentinel == 0) ? key : first_sentinel; // ?saw sentinel?
 157       _table[key] = n;          // Insert into table!
 158       debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 159       check_grow();             // Grow table if insert hit limit
 160       return NULL;              // Miss!
 161     }
 162     else if( first_sentinel == 0 && k == _sentinel ) {
 163       first_sentinel = key;    // Can insert here
 164     }
 165 
 166   }
 167   ShouldNotReachHere();
 168   return NULL;
 169 }
 170 
 171 //------------------------------hash_insert------------------------------------
 172 // Insert into hash table
 173 void NodeHash::hash_insert( Node *n ) {
 174   // // "conflict" comments -- print nodes that conflict
 175   // bool conflict = false;
 176   // n->set_hash();
 177   uint hash = n->hash();
 178   if (hash == Node::NO_HASH) {
 179     return;
 180   }
 181   check_grow();
 182   uint key = hash & (_max-1);
 183   uint stride = key | 0x01;
 184 
 185   while( 1 ) {                  // While probing hash table
 186     debug_only( _insert_probes++ );
 187     Node *k = _table[key];      // Get hashed value
 188     if( !k || (k == _sentinel) ) break;       // Found a slot
 189     assert( k != n, "already inserted" );
 190     // if( PrintCompilation && PrintOptoStatistics && Verbose ) { tty->print("  conflict: "); k->dump(); conflict = true; }
 191     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
 192   }
 193   _table[key] = n;              // Insert into table!
 194   debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 195   // if( conflict ) { n->dump(); }
 196 }
 197 
 198 //------------------------------hash_delete------------------------------------
 199 // Replace in hash table with sentinel
 200 bool NodeHash::hash_delete( const Node *n ) {
 201   Node *k;
 202   uint hash = n->hash();
 203   if (hash == Node::NO_HASH) {
 204     debug_only( _delete_misses++ );
 205     return false;
 206   }
 207   uint key = hash & (_max-1);
 208   uint stride = key | 0x01;
 209   debug_only( uint counter = 0; );
 210   for( ; /* (k != NULL) && (k != _sentinel) */; ) {
 211     debug_only( counter++ );
 212     debug_only( _delete_probes++ );
 213     k = _table[key];            // Get hashed value
 214     if( !k ) {                  // Miss?
 215       debug_only( _delete_misses++ );
 216 #ifdef ASSERT
 217       if( VerifyOpto ) {
 218         for( uint i=0; i < _max; i++ )
 219           assert( _table[i] != n, "changed edges with rehashing" );
 220       }
 221 #endif
 222       return false;             // Miss! Not in chain
 223     }
 224     else if( n == k ) {
 225       debug_only( _delete_hits++ );
 226       _table[key] = _sentinel;  // Hit! Label as deleted entry
 227       debug_only(((Node*)n)->exit_hash_lock()); // Unlock the node upon removal from table.
 228       return true;
 229     }
 230     else {
 231       // collision: move through table with prime offset
 232       key = (key + stride/*7*/) & (_max-1);
 233       assert( counter <= _insert_limit, "Cycle in hash-table");
 234     }
 235   }
 236   ShouldNotReachHere();
 237   return false;
 238 }
 239 
 240 //------------------------------round_up---------------------------------------
 241 // Round up to nearest power of 2
 242 uint NodeHash::round_up( uint x ) {
 243   x += (x>>2);                  // Add 25% slop
 244   if( x <16 ) return 16;        // Small stuff
 245   uint i=16;
 246   while( i < x ) i <<= 1;       // Double to fit
 247   return i;                     // Return hash table size
 248 }
 249 
 250 //------------------------------grow-------------------------------------------
 251 // Grow _table to next power of 2 and insert old entries
 252 void  NodeHash::grow() {
 253   // Record old state
 254   uint   old_max   = _max;
 255   Node **old_table = _table;
 256   // Construct new table with twice the space
 257   _grows++;
 258   _total_inserts       += _inserts;
 259   _total_insert_probes += _insert_probes;
 260   _inserts         = 0;
 261   _insert_probes   = 0;
 262   _max     = _max << 1;
 263   _table   = NEW_ARENA_ARRAY( _a , Node* , _max ); // (Node**)_a->Amalloc( _max * sizeof(Node*) );
 264   memset(_table,0,sizeof(Node*)*_max);
 265   _insert_limit = insert_limit();
 266   // Insert old entries into the new table
 267   for( uint i = 0; i < old_max; i++ ) {
 268     Node *m = *old_table++;
 269     if( !m || m == _sentinel ) continue;
 270     debug_only(m->exit_hash_lock()); // Unlock the node upon removal from old table.
 271     hash_insert(m);
 272   }
 273 }
 274 
 275 //------------------------------clear------------------------------------------
 276 // Clear all entries in _table to NULL but keep storage
 277 void  NodeHash::clear() {
 278 #ifdef ASSERT
 279   // Unlock all nodes upon removal from table.
 280   for (uint i = 0; i < _max; i++) {
 281     Node* n = _table[i];
 282     if (!n || n == _sentinel)  continue;
 283     n->exit_hash_lock();
 284   }
 285 #endif
 286 
 287   memset( _table, 0, _max * sizeof(Node*) );
 288 }
 289 
 290 //-----------------------remove_useless_nodes----------------------------------
 291 // Remove useless nodes from value table,
 292 // implementation does not depend on hash function
 293 void NodeHash::remove_useless_nodes(VectorSet &useful) {
 294 
 295   // Dead nodes in the hash table inherited from GVN should not replace
 296   // existing nodes, remove dead nodes.
 297   uint max = size();
 298   Node *sentinel_node = sentinel();
 299   for( uint i = 0; i < max; ++i ) {
 300     Node *n = at(i);
 301     if(n != NULL && n != sentinel_node && !useful.test(n->_idx)) {
 302       debug_only(n->exit_hash_lock()); // Unlock the node when removed
 303       _table[i] = sentinel_node;       // Replace with placeholder
 304     }
 305   }
 306 }
 307 
 308 #ifndef PRODUCT
 309 //------------------------------dump-------------------------------------------
 310 // Dump statistics for the hash table
 311 void NodeHash::dump() {
 312   _total_inserts       += _inserts;
 313   _total_insert_probes += _insert_probes;
 314   if( PrintCompilation && PrintOptoStatistics && Verbose && (_inserts > 0) ) { // PrintOptoGVN
 315     if( PrintCompilation2 ) {
 316       for( uint i=0; i<_max; i++ )
 317       if( _table[i] )
 318         tty->print("%d/%d/%d ",i,_table[i]->hash()&(_max-1),_table[i]->_idx);
 319     }
 320     tty->print("\nGVN Hash stats:  %d grows to %d max_size\n", _grows, _max);
 321     tty->print("  %d/%d (%8.1f%% full)\n", _inserts, _max, (double)_inserts/_max*100.0);
 322     tty->print("  %dp/(%dh+%dm) (%8.2f probes/lookup)\n", _look_probes, _lookup_hits, _lookup_misses, (double)_look_probes/(_lookup_hits+_lookup_misses));
 323     tty->print("  %dp/%di (%8.2f probes/insert)\n", _total_insert_probes, _total_inserts, (double)_total_insert_probes/_total_inserts);
 324     // sentinels increase lookup cost, but not insert cost
 325     assert((_lookup_misses+_lookup_hits)*4+100 >= _look_probes, "bad hash function");
 326     assert( _inserts+(_inserts>>3) < _max, "table too full" );
 327     assert( _inserts*3+100 >= _insert_probes, "bad hash function" );
 328   }
 329 }
 330 
 331 Node *NodeHash::find_index(uint idx) { // For debugging
 332   // Find an entry by its index value
 333   for( uint i = 0; i < _max; i++ ) {
 334     Node *m = _table[i];
 335     if( !m || m == _sentinel ) continue;
 336     if( m->_idx == (uint)idx ) return m;
 337   }
 338   return NULL;
 339 }
 340 #endif
 341 
 342 #ifdef ASSERT
 343 NodeHash::~NodeHash() {
 344   // Unlock all nodes upon destruction of table.
 345   if (_table != (Node**)badAddress)  clear();
 346 }
 347 
 348 void NodeHash::operator=(const NodeHash& nh) {
 349   // Unlock all nodes upon replacement of table.
 350   if (&nh == this)  return;
 351   if (_table != (Node**)badAddress)  clear();
 352   memcpy(this, &nh, sizeof(*this));
 353   // Do not increment hash_lock counts again.
 354   // Instead, be sure we never again use the source table.
 355   ((NodeHash*)&nh)->_table = (Node**)badAddress;
 356 }
 357 
 358 
 359 #endif
 360 
 361 
 362 //=============================================================================
 363 //------------------------------PhaseRemoveUseless-----------------------------
 364 // 1) Use a breadthfirst walk to collect useful nodes reachable from root.
 365 PhaseRemoveUseless::PhaseRemoveUseless( PhaseGVN *gvn, Unique_Node_List *worklist ) : Phase(Remove_Useless),
 366   _useful(Thread::current()->resource_area()) {
 367 
 368   // Implementation requires 'UseLoopSafepoints == true' and an edge from root
 369   // to each SafePointNode at a backward branch.  Inserted in add_safepoint().
 370   if( !UseLoopSafepoints || !OptoRemoveUseless ) return;
 371 
 372   // Identify nodes that are reachable from below, useful.
 373   C->identify_useful_nodes(_useful);
 374 
 375   // Remove all useless nodes from PhaseValues' recorded types
 376   // Must be done before disconnecting nodes to preserve hash-table-invariant
 377   gvn->remove_useless_nodes(_useful.member_set());
 378 
 379   // Remove all useless nodes from future worklist
 380   worklist->remove_useless_nodes(_useful.member_set());
 381 
 382   // Disconnect 'useless' nodes that are adjacent to useful nodes
 383   C->remove_useless_nodes(_useful);
 384 
 385   // Remove edges from "root" to each SafePoint at a backward branch.
 386   // They were inserted during parsing (see add_safepoint()) to make infinite
 387   // loops without calls or exceptions visible to root, i.e., useful.
 388   Node *root = C->root();
 389   if( root != NULL ) {
 390     for( uint i = root->req(); i < root->len(); ++i ) {
 391       Node *n = root->in(i);
 392       if( n != NULL && n->is_SafePoint() ) {
 393         root->rm_prec(i);
 394         --i;
 395       }
 396     }
 397   }
 398 }
 399 
 400 
 401 //=============================================================================
 402 //------------------------------PhaseTransform---------------------------------
 403 PhaseTransform::PhaseTransform( PhaseNumber pnum ) : Phase(pnum),
 404   _arena(Thread::current()->resource_area()),
 405   _nodes(_arena),
 406   _types(_arena)
 407 {
 408   init_con_caches();
 409 #ifndef PRODUCT
 410   clear_progress();
 411   clear_transforms();
 412   set_allow_progress(true);
 413 #endif
 414   // Force allocation for currently existing nodes
 415   _types.map(C->unique(), NULL);
 416 }
 417 
 418 //------------------------------PhaseTransform---------------------------------
 419 PhaseTransform::PhaseTransform( Arena *arena, PhaseNumber pnum ) : Phase(pnum),
 420   _arena(arena),
 421   _nodes(arena),
 422   _types(arena)
 423 {
 424   init_con_caches();
 425 #ifndef PRODUCT
 426   clear_progress();
 427   clear_transforms();
 428   set_allow_progress(true);
 429 #endif
 430   // Force allocation for currently existing nodes
 431   _types.map(C->unique(), NULL);
 432 }
 433 
 434 //------------------------------PhaseTransform---------------------------------
 435 // Initialize with previously generated type information
 436 PhaseTransform::PhaseTransform( PhaseTransform *pt, PhaseNumber pnum ) : Phase(pnum),
 437   _arena(pt->_arena),
 438   _nodes(pt->_nodes),
 439   _types(pt->_types)
 440 {
 441   init_con_caches();
 442 #ifndef PRODUCT
 443   clear_progress();
 444   clear_transforms();
 445   set_allow_progress(true);
 446 #endif
 447 }
 448 
 449 void PhaseTransform::init_con_caches() {
 450   memset(_icons,0,sizeof(_icons));
 451   memset(_lcons,0,sizeof(_lcons));
 452   memset(_zcons,0,sizeof(_zcons));
 453 }
 454 
 455 
 456 //--------------------------------find_int_type--------------------------------
 457 const TypeInt* PhaseTransform::find_int_type(Node* n) {
 458   if (n == NULL)  return NULL;
 459   // Call type_or_null(n) to determine node's type since we might be in
 460   // parse phase and call n->Value() may return wrong type.
 461   // (For example, a phi node at the beginning of loop parsing is not ready.)
 462   const Type* t = type_or_null(n);
 463   if (t == NULL)  return NULL;
 464   return t->isa_int();
 465 }
 466 
 467 
 468 //-------------------------------find_long_type--------------------------------
 469 const TypeLong* PhaseTransform::find_long_type(Node* n) {
 470   if (n == NULL)  return NULL;
 471   // (See comment above on type_or_null.)
 472   const Type* t = type_or_null(n);
 473   if (t == NULL)  return NULL;
 474   return t->isa_long();
 475 }
 476 
 477 
 478 #ifndef PRODUCT
 479 void PhaseTransform::dump_old2new_map() const {
 480   _nodes.dump();
 481 }
 482 
 483 void PhaseTransform::dump_new( uint nidx ) const {
 484   for( uint i=0; i<_nodes.Size(); i++ )
 485     if( _nodes[i] && _nodes[i]->_idx == nidx ) {
 486       _nodes[i]->dump();
 487       tty->cr();
 488       tty->print_cr("Old index= %d",i);
 489       return;
 490     }
 491   tty->print_cr("Node %d not found in the new indices", nidx);
 492 }
 493 
 494 //------------------------------dump_types-------------------------------------
 495 void PhaseTransform::dump_types( ) const {
 496   _types.dump();
 497 }
 498 
 499 //------------------------------dump_nodes_and_types---------------------------
 500 void PhaseTransform::dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl) {
 501   VectorSet visited(Thread::current()->resource_area());
 502   dump_nodes_and_types_recur( root, depth, only_ctrl, visited );
 503 }
 504 
 505 //------------------------------dump_nodes_and_types_recur---------------------
 506 void PhaseTransform::dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited) {
 507   if( !n ) return;
 508   if( depth == 0 ) return;
 509   if( visited.test_set(n->_idx) ) return;
 510   for( uint i=0; i<n->len(); i++ ) {
 511     if( only_ctrl && !(n->is_Region()) && i != TypeFunc::Control ) continue;
 512     dump_nodes_and_types_recur( n->in(i), depth-1, only_ctrl, visited );
 513   }
 514   n->dump();
 515   if (type_or_null(n) != NULL) {
 516     tty->print("      "); type(n)->dump(); tty->cr();
 517   }
 518 }
 519 
 520 #endif
 521 
 522 
 523 //=============================================================================
 524 //------------------------------PhaseValues------------------------------------
 525 // Set minimum table size to "255"
 526 PhaseValues::PhaseValues( Arena *arena, uint est_max_size ) : PhaseTransform(arena, GVN), _table(arena, est_max_size) {
 527   NOT_PRODUCT( clear_new_values(); )
 528 }
 529 
 530 //------------------------------PhaseValues------------------------------------
 531 // Set minimum table size to "255"
 532 PhaseValues::PhaseValues( PhaseValues *ptv ) : PhaseTransform( ptv, GVN ),
 533   _table(&ptv->_table) {
 534   NOT_PRODUCT( clear_new_values(); )
 535 }
 536 
 537 //------------------------------PhaseValues------------------------------------
 538 // Used by +VerifyOpto.  Clear out hash table but copy _types array.
 539 PhaseValues::PhaseValues( PhaseValues *ptv, const char *dummy ) : PhaseTransform( ptv, GVN ),
 540   _table(ptv->arena(),ptv->_table.size()) {
 541   NOT_PRODUCT( clear_new_values(); )
 542 }
 543 
 544 //------------------------------~PhaseValues-----------------------------------
 545 #ifndef PRODUCT
 546 PhaseValues::~PhaseValues() {
 547   _table.dump();
 548 
 549   // Statistics for value progress and efficiency
 550   if( PrintCompilation && Verbose && WizardMode ) {
 551     tty->print("\n%sValues: %d nodes ---> %d/%d (%d)",
 552       is_IterGVN() ? "Iter" : "    ", C->unique(), made_progress(), made_transforms(), made_new_values());
 553     if( made_transforms() != 0 ) {
 554       tty->print_cr("  ratio %f", made_progress()/(float)made_transforms() );
 555     } else {
 556       tty->cr();
 557     }
 558   }
 559 }
 560 #endif
 561 
 562 //------------------------------makecon----------------------------------------
 563 ConNode* PhaseTransform::makecon(const Type *t) {
 564   assert(t->singleton(), "must be a constant");
 565   assert(!t->empty() || t == Type::TOP, "must not be vacuous range");
 566   switch (t->base()) {  // fast paths
 567   case Type::Half:
 568   case Type::Top:  return (ConNode*) C->top();
 569   case Type::Int:  return intcon( t->is_int()->get_con() );
 570   case Type::Long: return longcon( t->is_long()->get_con() );
 571   }
 572   if (t->is_zero_type())
 573     return zerocon(t->basic_type());
 574   return uncached_makecon(t);
 575 }
 576 
 577 //--------------------------uncached_makecon-----------------------------------
 578 // Make an idealized constant - one of ConINode, ConPNode, etc.
 579 ConNode* PhaseValues::uncached_makecon(const Type *t) {
 580   assert(t->singleton(), "must be a constant");
 581   ConNode* x = ConNode::make(C, t);
 582   ConNode* k = (ConNode*)hash_find_insert(x); // Value numbering
 583   if (k == NULL) {
 584     set_type(x, t);             // Missed, provide type mapping
 585     GrowableArray<Node_Notes*>* nna = C->node_note_array();
 586     if (nna != NULL) {
 587       Node_Notes* loc = C->locate_node_notes(nna, x->_idx, true);
 588       loc->clear(); // do not put debug info on constants
 589     }
 590   } else {
 591     x->destruct();              // Hit, destroy duplicate constant
 592     x = k;                      // use existing constant
 593   }
 594   return x;
 595 }
 596 
 597 //------------------------------intcon-----------------------------------------
 598 // Fast integer constant.  Same as "transform(new ConINode(TypeInt::make(i)))"
 599 ConINode* PhaseTransform::intcon(int i) {
 600   // Small integer?  Check cache! Check that cached node is not dead
 601   if (i >= _icon_min && i <= _icon_max) {
 602     ConINode* icon = _icons[i-_icon_min];
 603     if (icon != NULL && icon->in(TypeFunc::Control) != NULL)
 604       return icon;
 605   }
 606   ConINode* icon = (ConINode*) uncached_makecon(TypeInt::make(i));
 607   assert(icon->is_Con(), "");
 608   if (i >= _icon_min && i <= _icon_max)
 609     _icons[i-_icon_min] = icon;   // Cache small integers
 610   return icon;
 611 }
 612 
 613 //------------------------------longcon----------------------------------------
 614 // Fast long constant.
 615 ConLNode* PhaseTransform::longcon(jlong l) {
 616   // Small integer?  Check cache! Check that cached node is not dead
 617   if (l >= _lcon_min && l <= _lcon_max) {
 618     ConLNode* lcon = _lcons[l-_lcon_min];
 619     if (lcon != NULL && lcon->in(TypeFunc::Control) != NULL)
 620       return lcon;
 621   }
 622   ConLNode* lcon = (ConLNode*) uncached_makecon(TypeLong::make(l));
 623   assert(lcon->is_Con(), "");
 624   if (l >= _lcon_min && l <= _lcon_max)
 625     _lcons[l-_lcon_min] = lcon;      // Cache small integers
 626   return lcon;
 627 }
 628 
 629 //------------------------------zerocon-----------------------------------------
 630 // Fast zero or null constant. Same as "transform(ConNode::make(Type::get_zero_type(bt)))"
 631 ConNode* PhaseTransform::zerocon(BasicType bt) {
 632   assert((uint)bt <= _zcon_max, "domain check");
 633   ConNode* zcon = _zcons[bt];
 634   if (zcon != NULL && zcon->in(TypeFunc::Control) != NULL)
 635     return zcon;
 636   zcon = (ConNode*) uncached_makecon(Type::get_zero_type(bt));
 637   _zcons[bt] = zcon;
 638   return zcon;
 639 }
 640 
 641 
 642 
 643 //=============================================================================
 644 //------------------------------transform--------------------------------------
 645 // Return a node which computes the same function as this node, but in a
 646 // faster or cheaper fashion.
 647 Node *PhaseGVN::transform( Node *n ) {
 648   return transform_no_reclaim(n);
 649 }
 650 
 651 //------------------------------transform--------------------------------------
 652 // Return a node which computes the same function as this node, but
 653 // in a faster or cheaper fashion.
 654 Node *PhaseGVN::transform_no_reclaim( Node *n ) {
 655   NOT_PRODUCT( set_transforms(); )
 656 
 657   // Apply the Ideal call in a loop until it no longer applies
 658   Node *k = n;
 659   NOT_PRODUCT( uint loop_count = 0; )
 660   while( 1 ) {
 661     Node *i = k->Ideal(this, /*can_reshape=*/false);
 662     if( !i ) break;
 663     assert( i->_idx >= k->_idx, "Idealize should return new nodes, use Identity to return old nodes" );
 664     k = i;
 665     assert(loop_count++ < K, "infinite loop in PhaseGVN::transform");
 666   }
 667   NOT_PRODUCT( if( loop_count != 0 ) { set_progress(); } )
 668 
 669 
 670   // If brand new node, make space in type array.
 671   ensure_type_or_null(k);
 672 
 673   // Since I just called 'Value' to compute the set of run-time values
 674   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
 675   // cache Value.  Later requests for the local phase->type of this Node can
 676   // use the cached Value instead of suffering with 'bottom_type'.
 677   const Type *t = k->Value(this); // Get runtime Value set
 678   assert(t != NULL, "value sanity");
 679   if (type_or_null(k) != t) {
 680 #ifndef PRODUCT
 681     // Do not count initial visit to node as a transformation
 682     if (type_or_null(k) == NULL) {
 683       inc_new_values();
 684       set_progress();
 685     }
 686 #endif
 687     set_type(k, t);
 688     // If k is a TypeNode, capture any more-precise type permanently into Node
 689     k->raise_bottom_type(t);
 690   }
 691 
 692   if( t->singleton() && !k->is_Con() ) {
 693     NOT_PRODUCT( set_progress(); )
 694     return makecon(t);          // Turn into a constant
 695   }
 696 
 697   // Now check for Identities
 698   Node *i = k->Identity(this);  // Look for a nearby replacement
 699   if( i != k ) {                // Found? Return replacement!
 700     NOT_PRODUCT( set_progress(); )
 701     return i;
 702   }
 703 
 704   // Global Value Numbering
 705   i = hash_find_insert(k);      // Insert if new
 706   if( i && (i != k) ) {
 707     // Return the pre-existing node
 708     NOT_PRODUCT( set_progress(); )
 709     return i;
 710   }
 711 
 712   // Return Idealized original
 713   return k;
 714 }
 715 
 716 #ifdef ASSERT
 717 //------------------------------dead_loop_check--------------------------------
 718 // Check for a simple dead loop when a data node references itself directly
 719 // or through an other data node excluding cons and phis.
 720 void PhaseGVN::dead_loop_check( Node *n ) {
 721   // Phi may reference itself in a loop
 722   if (n != NULL && !n->is_dead_loop_safe() && !n->is_CFG()) {
 723     // Do 2 levels check and only data inputs.
 724     bool no_dead_loop = true;
 725     uint cnt = n->req();
 726     for (uint i = 1; i < cnt && no_dead_loop; i++) {
 727       Node *in = n->in(i);
 728       if (in == n) {
 729         no_dead_loop = false;
 730       } else if (in != NULL && !in->is_dead_loop_safe()) {
 731         uint icnt = in->req();
 732         for (uint j = 1; j < icnt && no_dead_loop; j++) {
 733           if (in->in(j) == n || in->in(j) == in)
 734             no_dead_loop = false;
 735         }
 736       }
 737     }
 738     if (!no_dead_loop) n->dump(3);
 739     assert(no_dead_loop, "dead loop detected");
 740   }
 741 }
 742 #endif
 743 
 744 //=============================================================================
 745 //------------------------------PhaseIterGVN-----------------------------------
 746 // Initialize hash table to fresh and clean for +VerifyOpto
 747 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn, const char *dummy ) : PhaseGVN(igvn,dummy), _worklist( ),
 748                                                                       _delay_transform(false) {
 749 }
 750 
 751 //------------------------------PhaseIterGVN-----------------------------------
 752 // Initialize with previous PhaseIterGVN info; used by PhaseCCP
 753 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn ) : PhaseGVN(igvn),
 754                                                    _worklist( igvn->_worklist ),
 755                                                    _delay_transform(igvn->_delay_transform)
 756 {
 757 }
 758 
 759 //------------------------------PhaseIterGVN-----------------------------------
 760 // Initialize with previous PhaseGVN info from Parser
 761 PhaseIterGVN::PhaseIterGVN( PhaseGVN *gvn ) : PhaseGVN(gvn),
 762                                               _worklist(*C->for_igvn()),
 763                                               _delay_transform(false)
 764 {
 765   uint max;
 766 
 767   // Dead nodes in the hash table inherited from GVN were not treated as
 768   // roots during def-use info creation; hence they represent an invisible
 769   // use.  Clear them out.
 770   max = _table.size();
 771   for( uint i = 0; i < max; ++i ) {
 772     Node *n = _table.at(i);
 773     if(n != NULL && n != _table.sentinel() && n->outcnt() == 0) {
 774       if( n->is_top() ) continue;
 775       assert( false, "Parse::remove_useless_nodes missed this node");
 776       hash_delete(n);
 777     }
 778   }
 779 
 780   // Any Phis or Regions on the worklist probably had uses that could not
 781   // make more progress because the uses were made while the Phis and Regions
 782   // were in half-built states.  Put all uses of Phis and Regions on worklist.
 783   max = _worklist.size();
 784   for( uint j = 0; j < max; j++ ) {
 785     Node *n = _worklist.at(j);
 786     uint uop = n->Opcode();
 787     if( uop == Op_Phi || uop == Op_Region ||
 788         n->is_Type() ||
 789         n->is_Mem() )
 790       add_users_to_worklist(n);
 791   }
 792 }
 793 
 794 
 795 #ifndef PRODUCT
 796 void PhaseIterGVN::verify_step(Node* n) {
 797   _verify_window[_verify_counter % _verify_window_size] = n;
 798   ++_verify_counter;
 799   ResourceMark rm;
 800   ResourceArea *area = Thread::current()->resource_area();
 801   VectorSet old_space(area), new_space(area);
 802   if (C->unique() < 1000 ||
 803       0 == _verify_counter % (C->unique() < 10000 ? 10 : 100)) {
 804     ++_verify_full_passes;
 805     Node::verify_recur(C->root(), -1, old_space, new_space);
 806   }
 807   const int verify_depth = 4;
 808   for ( int i = 0; i < _verify_window_size; i++ ) {
 809     Node* n = _verify_window[i];
 810     if ( n == NULL )  continue;
 811     if( n->in(0) == NodeSentinel ) {  // xform_idom
 812       _verify_window[i] = n->in(1);
 813       --i; continue;
 814     }
 815     // Typical fanout is 1-2, so this call visits about 6 nodes.
 816     Node::verify_recur(n, verify_depth, old_space, new_space);
 817   }
 818 }
 819 #endif
 820 
 821 
 822 //------------------------------init_worklist----------------------------------
 823 // Initialize worklist for each node.
 824 void PhaseIterGVN::init_worklist( Node *n ) {
 825   if( _worklist.member(n) ) return;
 826   _worklist.push(n);
 827   uint cnt = n->req();
 828   for( uint i =0 ; i < cnt; i++ ) {
 829     Node *m = n->in(i);
 830     if( m ) init_worklist(m);
 831   }
 832 }
 833 
 834 //------------------------------optimize---------------------------------------
 835 void PhaseIterGVN::optimize() {
 836   debug_only(uint num_processed  = 0;);
 837 #ifndef PRODUCT
 838   {
 839     _verify_counter = 0;
 840     _verify_full_passes = 0;
 841     for ( int i = 0; i < _verify_window_size; i++ ) {
 842       _verify_window[i] = NULL;
 843     }
 844   }
 845 #endif
 846 
 847   // Pull from worklist; transform node;
 848   // If node has changed: update edge info and put uses on worklist.
 849   while( _worklist.size() ) {
 850     Node *n  = _worklist.pop();
 851     if (TraceIterativeGVN && Verbose) {
 852       tty->print("  Pop ");
 853       NOT_PRODUCT( n->dump(); )
 854       debug_only(if( (num_processed++ % 100) == 0 ) _worklist.print_set();)
 855     }
 856 
 857     if (n->outcnt() != 0) {
 858 
 859 #ifndef PRODUCT
 860       uint wlsize = _worklist.size();
 861       const Type* oldtype = type_or_null(n);
 862 #endif //PRODUCT
 863 
 864       Node *nn = transform_old(n);
 865 
 866 #ifndef PRODUCT
 867       if (TraceIterativeGVN) {
 868         const Type* newtype = type_or_null(n);
 869         if (nn != n) {
 870           // print old node
 871           tty->print("< ");
 872           if (oldtype != newtype && oldtype != NULL) {
 873             oldtype->dump();
 874           }
 875           do { tty->print("\t"); } while (tty->position() < 16);
 876           tty->print("<");
 877           n->dump();
 878         }
 879         if (oldtype != newtype || nn != n) {
 880           // print new node and/or new type
 881           if (oldtype == NULL) {
 882             tty->print("* ");
 883           } else if (nn != n) {
 884             tty->print("> ");
 885           } else {
 886             tty->print("= ");
 887           }
 888           if (newtype == NULL) {
 889             tty->print("null");
 890           } else {
 891             newtype->dump();
 892           }
 893           do { tty->print("\t"); } while (tty->position() < 16);
 894           nn->dump();
 895         }
 896         if (Verbose && wlsize < _worklist.size()) {
 897           tty->print("  Push {");
 898           while (wlsize != _worklist.size()) {
 899             Node* pushed = _worklist.at(wlsize++);
 900             tty->print(" %d", pushed->_idx);
 901           }
 902           tty->print_cr(" }");
 903         }
 904       }
 905       if( VerifyIterativeGVN && nn != n ) {
 906         verify_step((Node*) NULL);  // ignore n, it might be subsumed
 907       }
 908 #endif
 909     } else if (!n->is_top()) {
 910       remove_dead_node(n);
 911     }
 912   }
 913 
 914 #ifndef PRODUCT
 915   C->verify_graph_edges();
 916   if( VerifyOpto && allow_progress() ) {
 917     // Must turn off allow_progress to enable assert and break recursion
 918     C->root()->verify();
 919     { // Check if any progress was missed using IterGVN
 920       // Def-Use info enables transformations not attempted in wash-pass
 921       // e.g. Region/Phi cleanup, ...
 922       // Null-check elision -- may not have reached fixpoint
 923       //                       do not propagate to dominated nodes
 924       ResourceMark rm;
 925       PhaseIterGVN igvn2(this,"Verify"); // Fresh and clean!
 926       // Fill worklist completely
 927       igvn2.init_worklist(C->root());
 928 
 929       igvn2.set_allow_progress(false);
 930       igvn2.optimize();
 931       igvn2.set_allow_progress(true);
 932     }
 933   }
 934   if ( VerifyIterativeGVN && PrintOpto ) {
 935     if ( _verify_counter == _verify_full_passes )
 936       tty->print_cr("VerifyIterativeGVN: %d transforms and verify passes",
 937                     _verify_full_passes);
 938     else
 939       tty->print_cr("VerifyIterativeGVN: %d transforms, %d full verify passes",
 940                   _verify_counter, _verify_full_passes);
 941   }
 942 #endif
 943 }
 944 
 945 
 946 //------------------register_new_node_with_optimizer---------------------------
 947 // Register a new node with the optimizer.  Update the types array, the def-use
 948 // info.  Put on worklist.
 949 Node* PhaseIterGVN::register_new_node_with_optimizer(Node* n, Node* orig) {
 950   set_type_bottom(n);
 951   _worklist.push(n);
 952   if (orig != NULL)  C->copy_node_notes_to(n, orig);
 953   return n;
 954 }
 955 
 956 //------------------------------transform--------------------------------------
 957 // Non-recursive: idealize Node 'n' with respect to its inputs and its value
 958 Node *PhaseIterGVN::transform( Node *n ) {
 959   if (_delay_transform) {
 960     // Register the node but don't optimize for now
 961     register_new_node_with_optimizer(n);
 962     return n;
 963   }
 964 
 965   // If brand new node, make space in type array, and give it a type.
 966   ensure_type_or_null(n);
 967   if (type_or_null(n) == NULL) {
 968     set_type_bottom(n);
 969   }
 970 
 971   return transform_old(n);
 972 }
 973 
 974 //------------------------------transform_old----------------------------------
 975 Node *PhaseIterGVN::transform_old( Node *n ) {
 976 #ifndef PRODUCT
 977   debug_only(uint loop_count = 0;);
 978   set_transforms();
 979 #endif
 980   // Remove 'n' from hash table in case it gets modified
 981   _table.hash_delete(n);
 982   if( VerifyIterativeGVN ) {
 983    assert( !_table.find_index(n->_idx), "found duplicate entry in table");
 984   }
 985 
 986   // If n computes a constant, replace it with a constant now to skip unneeded
 987   // ideal transformations
 988   const Type* t_n = type_or_null(n);
 989   if( t_n != NULL && t_n->singleton() && !n->is_Con() ) {
 990     NOT_PRODUCT( set_progress(); )
 991     Node *con = makecon(t_n);     // Make a constant
 992     add_users_to_worklist( n );
 993     subsume_node( n, con );     // Everybody using n now uses con
 994     return con;
 995   }
 996 
 997   // Apply the Ideal call in a loop until it no longer applies
 998   Node *k = n;
 999   DEBUG_ONLY(dead_loop_check(k);)
1000   DEBUG_ONLY(bool is_new = (k->outcnt() == 0);)
1001   Node *i = k->Ideal(this, /*can_reshape=*/true);
1002   assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes");
1003 #ifndef PRODUCT
1004   if( VerifyIterativeGVN )
1005     verify_step(k);
1006   if( i && VerifyOpto ) {
1007     if( !allow_progress() ) {
1008       if (i->is_Add() && i->outcnt() == 1) {
1009         // Switched input to left side because this is the only use
1010       } else if( i->is_If() && (i->in(0) == NULL) ) {
1011         // This IF is dead because it is dominated by an equivalent IF When
1012         // dominating if changed, info is not propagated sparsely to 'this'
1013         // Propagating this info further will spuriously identify other
1014         // progress.
1015         return i;
1016       } else
1017         set_progress();
1018     } else
1019       set_progress();
1020   }
1021 #endif
1022 
1023   while( i ) {
1024 #ifndef PRODUCT
1025     debug_only( if( loop_count >= K ) i->dump(4); )
1026     assert(loop_count < K, "infinite loop in PhaseIterGVN::transform");
1027     debug_only( loop_count++; )
1028 #endif
1029     assert((i->_idx >= k->_idx) || i->is_top(), "Idealize should return new nodes, use Identity to return old nodes");
1030     // Made a change; put users of original Node on worklist
1031     add_users_to_worklist( k );
1032     // Replacing root of transform tree?
1033     if( k != i ) {
1034       // Make users of old Node now use new.
1035       subsume_node( k, i );
1036       k = i;
1037     }
1038     DEBUG_ONLY(dead_loop_check(k);)
1039     // Try idealizing again
1040     DEBUG_ONLY(is_new = (k->outcnt() == 0);)
1041     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 ) set_progress();
1047 #endif
1048   }
1049 
1050   // If brand new node, make space in type array.
1051   ensure_type_or_null(k);
1052 
1053   // See what kind of values 'k' takes on at runtime
1054   const Type *t = k->Value(this);
1055   assert(t != NULL, "value sanity");
1056 
1057   // Since I just called 'Value' to compute the set of run-time values
1058   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
1059   // cache Value.  Later requests for the local phase->type of this Node can
1060   // use the cached Value instead of suffering with 'bottom_type'.
1061   if (t != type_or_null(k)) {
1062     NOT_PRODUCT( set_progress(); )
1063     NOT_PRODUCT( inc_new_values();)
1064     set_type(k, t);
1065     // If k is a TypeNode, capture any more-precise type permanently into Node
1066     k->raise_bottom_type(t);
1067     // Move users of node to worklist
1068     add_users_to_worklist( k );
1069   }
1070 
1071   // If 'k' computes a constant, replace it with a constant
1072   if( t->singleton() && !k->is_Con() ) {
1073     NOT_PRODUCT( set_progress(); )
1074     Node *con = makecon(t);     // Make a constant
1075     add_users_to_worklist( k );
1076     subsume_node( k, con );     // Everybody using k now uses con
1077     return con;
1078   }
1079 
1080   // Now check for Identities
1081   i = k->Identity(this);        // Look for a nearby replacement
1082   if( i != k ) {                // Found? Return replacement!
1083     NOT_PRODUCT( set_progress(); )
1084     add_users_to_worklist( k );
1085     subsume_node( k, i );       // Everybody using k now uses i
1086     return i;
1087   }
1088 
1089   // Global Value Numbering
1090   i = hash_find_insert(k);      // Check for pre-existing node
1091   if( i && (i != k) ) {
1092     // Return the pre-existing node if it isn't dead
1093     NOT_PRODUCT( set_progress(); )
1094     add_users_to_worklist( k );
1095     subsume_node( k, i );       // Everybody using k now uses i
1096     return i;
1097   }
1098 
1099   // Return Idealized original
1100   return k;
1101 }
1102 
1103 //---------------------------------saturate------------------------------------
1104 const Type* PhaseIterGVN::saturate(const Type* new_type, const Type* old_type,
1105                                    const Type* limit_type) const {
1106   return new_type->narrow(old_type);
1107 }
1108 
1109 //------------------------------remove_globally_dead_node----------------------
1110 // Kill a globally dead Node.  All uses are also globally dead and are
1111 // aggressively trimmed.
1112 void PhaseIterGVN::remove_globally_dead_node( Node *dead ) {
1113   assert(dead != C->root(), "killing root, eh?");
1114   if (dead->is_top())  return;
1115   NOT_PRODUCT( set_progress(); )
1116   // Remove from iterative worklist
1117   _worklist.remove(dead);
1118   if (!dead->is_Con()) { // Don't kill cons but uses
1119     // Remove from hash table
1120     _table.hash_delete( dead );
1121     // Smash all inputs to 'dead', isolating him completely
1122     for( uint i = 0; i < dead->req(); i++ ) {
1123       Node *in = dead->in(i);
1124       if( in ) {                 // Points to something?
1125         dead->set_req(i,NULL);  // Kill the edge
1126         if (in->outcnt() == 0 && in != C->top()) {// Made input go dead?
1127           remove_dead_node(in); // Recursively remove
1128         } else if (in->outcnt() == 1 &&
1129                    in->has_special_unique_user()) {
1130           _worklist.push(in->unique_out());
1131         } else if (in->outcnt() <= 2 && dead->is_Phi()) {
1132           if( in->Opcode() == Op_Region )
1133             _worklist.push(in);
1134           else if( in->is_Store() ) {
1135             DUIterator_Fast imax, i = in->fast_outs(imax);
1136             _worklist.push(in->fast_out(i));
1137             i++;
1138             if(in->outcnt() == 2) {
1139               _worklist.push(in->fast_out(i));
1140               i++;
1141             }
1142             assert(!(i < imax), "sanity");
1143           }
1144         }
1145       }
1146     }
1147 
1148     if (dead->is_macro()) {
1149       C->remove_macro_node(dead);
1150     }
1151   }
1152   // Aggressively kill globally dead uses
1153   // (Cannot use DUIterator_Last because of the indefinite number
1154   // of edge deletions per loop trip.)
1155   while (dead->outcnt() > 0) {
1156     remove_globally_dead_node(dead->raw_out(0));
1157   }
1158 }
1159 
1160 //------------------------------subsume_node-----------------------------------
1161 // Remove users from node 'old' and add them to node 'nn'.
1162 void PhaseIterGVN::subsume_node( Node *old, Node *nn ) {
1163   assert( old != hash_find(old), "should already been removed" );
1164   assert( old != C->top(), "cannot subsume top node");
1165   // Copy debug or profile information to the new version:
1166   C->copy_node_notes_to(nn, old);
1167   // Move users of node 'old' to node 'nn'
1168   for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) {
1169     Node* use = old->last_out(i);  // for each use...
1170     // use might need re-hashing (but it won't if it's a new node)
1171     bool is_in_table = _table.hash_delete( use );
1172     // Update use-def info as well
1173     // We remove all occurrences of old within use->in,
1174     // so as to avoid rehashing any node more than once.
1175     // The hash table probe swamps any outer loop overhead.
1176     uint num_edges = 0;
1177     for (uint jmax = use->len(), j = 0; j < jmax; j++) {
1178       if (use->in(j) == old) {
1179         use->set_req(j, nn);
1180         ++num_edges;
1181       }
1182     }
1183     // Insert into GVN hash table if unique
1184     // If a duplicate, 'use' will be cleaned up when pulled off worklist
1185     if( is_in_table ) {
1186       hash_find_insert(use);
1187     }
1188     i -= num_edges;    // we deleted 1 or more copies of this edge
1189   }
1190 
1191   // Smash all inputs to 'old', isolating him completely
1192   Node *temp = new (C, 1) Node(1);
1193   temp->init_req(0,nn);     // Add a use to nn to prevent him from dying
1194   remove_dead_node( old );
1195   temp->del_req(0);         // Yank bogus edge
1196 #ifndef PRODUCT
1197   if( VerifyIterativeGVN ) {
1198     for ( int i = 0; i < _verify_window_size; i++ ) {
1199       if ( _verify_window[i] == old )
1200         _verify_window[i] = nn;
1201     }
1202   }
1203 #endif
1204   _worklist.remove(temp);   // this can be necessary
1205   temp->destruct();         // reuse the _idx of this little guy
1206 }
1207 
1208 //------------------------------add_users_to_worklist--------------------------
1209 void PhaseIterGVN::add_users_to_worklist0( Node *n ) {
1210   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1211     _worklist.push(n->fast_out(i));  // Push on worklist
1212   }
1213 }
1214 
1215 void PhaseIterGVN::add_users_to_worklist( Node *n ) {
1216   add_users_to_worklist0(n);
1217 
1218   // Move users of node to worklist
1219   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1220     Node* use = n->fast_out(i); // Get use
1221 
1222     if( use->is_Multi() ||      // Multi-definer?  Push projs on worklist
1223         use->is_Store() )       // Enable store/load same address
1224       add_users_to_worklist0(use);
1225 
1226     // If we changed the receiver type to a call, we need to revisit
1227     // the Catch following the call.  It's looking for a non-NULL
1228     // receiver to know when to enable the regular fall-through path
1229     // in addition to the NullPtrException path.
1230     if (use->is_CallDynamicJava() && n == use->in(TypeFunc::Parms)) {
1231       Node* p = use->as_CallDynamicJava()->proj_out(TypeFunc::Control);
1232       if (p != NULL) {
1233         add_users_to_worklist0(p);
1234       }
1235     }
1236 
1237     if( use->is_Cmp() ) {       // Enable CMP/BOOL optimization
1238       add_users_to_worklist(use); // Put Bool on worklist
1239       // Look for the 'is_x2logic' pattern: "x ? : 0 : 1" and put the
1240       // phi merging either 0 or 1 onto the worklist
1241       if (use->outcnt() > 0) {
1242         Node* bol = use->raw_out(0);
1243         if (bol->outcnt() > 0) {
1244           Node* iff = bol->raw_out(0);
1245           if (iff->outcnt() == 2) {
1246             Node* ifproj0 = iff->raw_out(0);
1247             Node* ifproj1 = iff->raw_out(1);
1248             if (ifproj0->outcnt() > 0 && ifproj1->outcnt() > 0) {
1249               Node* region0 = ifproj0->raw_out(0);
1250               Node* region1 = ifproj1->raw_out(0);
1251               if( region0 == region1 )
1252                 add_users_to_worklist0(region0);
1253             }
1254           }
1255         }
1256       }
1257     }
1258 
1259     uint use_op = use->Opcode();
1260     // If changed Cast input, check Phi users for simple cycles
1261     if( use->is_ConstraintCast() || use->is_CheckCastPP() ) {
1262       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1263         Node* u = use->fast_out(i2);
1264         if (u->is_Phi())
1265           _worklist.push(u);
1266       }
1267     }
1268     // If changed LShift inputs, check RShift users for useless sign-ext
1269     if( use_op == Op_LShiftI ) {
1270       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1271         Node* u = use->fast_out(i2);
1272         if (u->Opcode() == Op_RShiftI)
1273           _worklist.push(u);
1274       }
1275     }
1276     // If changed AddP inputs, check Stores for loop invariant
1277     if( use_op == Op_AddP ) {
1278       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1279         Node* u = use->fast_out(i2);
1280         if (u->is_Mem())
1281           _worklist.push(u);
1282       }
1283     }
1284     // If changed initialization activity, check dependent Stores
1285     if (use_op == Op_Allocate || use_op == Op_AllocateArray) {
1286       InitializeNode* init = use->as_Allocate()->initialization();
1287       if (init != NULL) {
1288         Node* imem = init->proj_out(TypeFunc::Memory);
1289         if (imem != NULL)  add_users_to_worklist0(imem);
1290       }
1291     }
1292     if (use_op == Op_Initialize) {
1293       Node* imem = use->as_Initialize()->proj_out(TypeFunc::Memory);
1294       if (imem != NULL)  add_users_to_worklist0(imem);
1295     }
1296   }
1297 }
1298 
1299 //=============================================================================
1300 #ifndef PRODUCT
1301 uint PhaseCCP::_total_invokes   = 0;
1302 uint PhaseCCP::_total_constants = 0;
1303 #endif
1304 //------------------------------PhaseCCP---------------------------------------
1305 // Conditional Constant Propagation, ala Wegman & Zadeck
1306 PhaseCCP::PhaseCCP( PhaseIterGVN *igvn ) : PhaseIterGVN(igvn) {
1307   NOT_PRODUCT( clear_constants(); )
1308   assert( _worklist.size() == 0, "" );
1309   // Clear out _nodes from IterGVN.  Must be clear to transform call.
1310   _nodes.clear();               // Clear out from IterGVN
1311   analyze();
1312 }
1313 
1314 #ifndef PRODUCT
1315 //------------------------------~PhaseCCP--------------------------------------
1316 PhaseCCP::~PhaseCCP() {
1317   inc_invokes();
1318   _total_constants += count_constants();
1319 }
1320 #endif
1321 
1322 
1323 #ifdef ASSERT
1324 static bool ccp_type_widens(const Type* t, const Type* t0) {
1325   assert(t->meet(t0) == t, "Not monotonic");
1326   switch (t->base() == t0->base() ? t->base() : Type::Top) {
1327   case Type::Int:
1328     assert(t0->isa_int()->_widen <= t->isa_int()->_widen, "widen increases");
1329     break;
1330   case Type::Long:
1331     assert(t0->isa_long()->_widen <= t->isa_long()->_widen, "widen increases");
1332     break;
1333   }
1334   return true;
1335 }
1336 #endif //ASSERT
1337 
1338 //------------------------------analyze----------------------------------------
1339 void PhaseCCP::analyze() {
1340   // Initialize all types to TOP, optimistic analysis
1341   for (int i = C->unique() - 1; i >= 0; i--)  {
1342     _types.map(i,Type::TOP);
1343   }
1344 
1345   // Push root onto worklist
1346   Unique_Node_List worklist;
1347   worklist.push(C->root());
1348 
1349   // Pull from worklist; compute new value; push changes out.
1350   // This loop is the meat of CCP.
1351   while( worklist.size() ) {
1352     Node *n = worklist.pop();
1353     const Type *t = n->Value(this);
1354     if (t != type(n)) {
1355       assert(ccp_type_widens(t, type(n)), "ccp type must widen");
1356 #ifndef PRODUCT
1357       if( TracePhaseCCP ) {
1358         t->dump();
1359         do { tty->print("\t"); } while (tty->position() < 16);
1360         n->dump();
1361       }
1362 #endif
1363       set_type(n, t);
1364       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1365         Node* m = n->fast_out(i);   // Get user
1366         if( m->is_Region() ) {  // New path to Region?  Must recheck Phis too
1367           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1368             Node* p = m->fast_out(i2); // Propagate changes to uses
1369             if( p->bottom_type() != type(p) ) // If not already bottomed out
1370               worklist.push(p); // Propagate change to user
1371           }
1372         }
1373         // If we changed the receiver type to a call, we need to revisit
1374         // the Catch following the call.  It's looking for a non-NULL
1375         // receiver to know when to enable the regular fall-through path
1376         // in addition to the NullPtrException path
1377         if (m->is_Call()) {
1378           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1379             Node* p = m->fast_out(i2);  // Propagate changes to uses
1380             if (p->is_Proj() && p->as_Proj()->_con == TypeFunc::Control && p->outcnt() == 1)
1381               worklist.push(p->unique_out());
1382           }
1383         }
1384         if( m->bottom_type() != type(m) ) // If not already bottomed out
1385           worklist.push(m);     // Propagate change to user
1386       }
1387     }
1388   }
1389 }
1390 
1391 //------------------------------do_transform-----------------------------------
1392 // Top level driver for the recursive transformer
1393 void PhaseCCP::do_transform() {
1394   // Correct leaves of new-space Nodes; they point to old-space.
1395   C->set_root( transform(C->root())->as_Root() );
1396   assert( C->top(),  "missing TOP node" );
1397   assert( C->root(), "missing root" );
1398 }
1399 
1400 //------------------------------transform--------------------------------------
1401 // Given a Node in old-space, clone him into new-space.
1402 // Convert any of his old-space children into new-space children.
1403 Node *PhaseCCP::transform( Node *n ) {
1404   Node *new_node = _nodes[n->_idx]; // Check for transformed node
1405   if( new_node != NULL )
1406     return new_node;                // Been there, done that, return old answer
1407   new_node = transform_once(n);     // Check for constant
1408   _nodes.map( n->_idx, new_node );  // Flag as having been cloned
1409 
1410   // Allocate stack of size _nodes.Size()/2 to avoid frequent realloc
1411   GrowableArray <Node *> trstack(C->unique() >> 1);
1412 
1413   trstack.push(new_node);           // Process children of cloned node
1414   while ( trstack.is_nonempty() ) {
1415     Node *clone = trstack.pop();
1416     uint cnt = clone->req();
1417     for( uint i = 0; i < cnt; i++ ) {          // For all inputs do
1418       Node *input = clone->in(i);
1419       if( input != NULL ) {                    // Ignore NULLs
1420         Node *new_input = _nodes[input->_idx]; // Check for cloned input node
1421         if( new_input == NULL ) {
1422           new_input = transform_once(input);   // Check for constant
1423           _nodes.map( input->_idx, new_input );// Flag as having been cloned
1424           trstack.push(new_input);
1425         }
1426         assert( new_input == clone->in(i), "insanity check");
1427       }
1428     }
1429   }
1430   return new_node;
1431 }
1432 
1433 
1434 //------------------------------transform_once---------------------------------
1435 // For PhaseCCP, transformation is IDENTITY unless Node computed a constant.
1436 Node *PhaseCCP::transform_once( Node *n ) {
1437   const Type *t = type(n);
1438   // Constant?  Use constant Node instead
1439   if( t->singleton() ) {
1440     Node *nn = n;               // Default is to return the original constant
1441     if( t == Type::TOP ) {
1442       // cache my top node on the Compile instance
1443       if( C->cached_top_node() == NULL || C->cached_top_node()->in(0) == NULL ) {
1444         C->set_cached_top_node( ConNode::make(C, Type::TOP) );
1445         set_type(C->top(), Type::TOP);
1446       }
1447       nn = C->top();
1448     }
1449     if( !n->is_Con() ) {
1450       if( t != Type::TOP ) {
1451         nn = makecon(t);        // ConNode::make(t);
1452         NOT_PRODUCT( inc_constants(); )
1453       } else if( n->is_Region() ) { // Unreachable region
1454         // Note: nn == C->top()
1455         n->set_req(0, NULL);        // Cut selfreference
1456         // Eagerly remove dead phis to avoid phis copies creation.
1457         for (DUIterator i = n->outs(); n->has_out(i); i++) {
1458           Node* m = n->out(i);
1459           if( m->is_Phi() ) {
1460             assert(type(m) == Type::TOP, "Unreachable region should not have live phis.");
1461             add_users_to_worklist(m);
1462             hash_delete(m); // Yank from hash before hacking edges
1463             subsume_node(m, nn);
1464             --i; // deleted this phi; rescan starting with next position
1465           }
1466         }
1467       }
1468       add_users_to_worklist(n); // Users of about-to-be-constant 'n'
1469       hash_delete(n);           // Removed 'n' from table before subsuming it
1470       subsume_node(n,nn);       // Update DefUse edges for new constant
1471     }
1472     return nn;
1473   }
1474 
1475   // If x is a TypeNode, capture any more-precise type permanently into Node
1476   if (t != n->bottom_type()) {
1477     hash_delete(n);             // changing bottom type may force a rehash
1478     n->raise_bottom_type(t);
1479     _worklist.push(n);          // n re-enters the hash table via the worklist
1480   }
1481 
1482   // Idealize graph using DU info.  Must clone() into new-space.
1483   // DU info is generally used to show profitability, progress or safety
1484   // (but generally not needed for correctness).
1485   Node *nn = n->Ideal_DU_postCCP(this);
1486 
1487   // TEMPORARY fix to ensure that 2nd GVN pass eliminates NULL checks
1488   switch( n->Opcode() ) {
1489   case Op_FastLock:      // Revisit FastLocks for lock coarsening
1490   case Op_If:
1491   case Op_CountedLoopEnd:
1492   case Op_Region:
1493   case Op_Loop:
1494   case Op_CountedLoop:
1495   case Op_Conv2B:
1496   case Op_Opaque1:
1497   case Op_Opaque2:
1498     _worklist.push(n);
1499     break;
1500   default:
1501     break;
1502   }
1503   if( nn ) {
1504     _worklist.push(n);
1505     // Put users of 'n' onto worklist for second igvn transform
1506     add_users_to_worklist(n);
1507     return nn;
1508   }
1509 
1510   return  n;
1511 }
1512 
1513 //---------------------------------saturate------------------------------------
1514 const Type* PhaseCCP::saturate(const Type* new_type, const Type* old_type,
1515                                const Type* limit_type) const {
1516   const Type* wide_type = new_type->widen(old_type);
1517   if (wide_type != new_type) {          // did we widen?
1518     // If so, we may have widened beyond the limit type.  Clip it back down.
1519     new_type = wide_type->filter(limit_type);
1520   }
1521   return new_type;
1522 }
1523 
1524 //------------------------------print_statistics-------------------------------
1525 #ifndef PRODUCT
1526 void PhaseCCP::print_statistics() {
1527   tty->print_cr("CCP: %d  constants found: %d", _total_invokes, _total_constants);
1528 }
1529 #endif
1530 
1531 
1532 //=============================================================================
1533 #ifndef PRODUCT
1534 uint PhasePeephole::_total_peepholes = 0;
1535 #endif
1536 //------------------------------PhasePeephole----------------------------------
1537 // Conditional Constant Propagation, ala Wegman & Zadeck
1538 PhasePeephole::PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg )
1539   : PhaseTransform(Peephole), _regalloc(regalloc), _cfg(cfg) {
1540   NOT_PRODUCT( clear_peepholes(); )
1541 }
1542 
1543 #ifndef PRODUCT
1544 //------------------------------~PhasePeephole---------------------------------
1545 PhasePeephole::~PhasePeephole() {
1546   _total_peepholes += count_peepholes();
1547 }
1548 #endif
1549 
1550 //------------------------------transform--------------------------------------
1551 Node *PhasePeephole::transform( Node *n ) {
1552   ShouldNotCallThis();
1553   return NULL;
1554 }
1555 
1556 //------------------------------do_transform-----------------------------------
1557 void PhasePeephole::do_transform() {
1558   bool method_name_not_printed = true;
1559 
1560   // Examine each basic block
1561   for( uint block_number = 1; block_number < _cfg._num_blocks; ++block_number ) {
1562     Block *block = _cfg._blocks[block_number];
1563     bool block_not_printed = true;
1564 
1565     // and each instruction within a block
1566     uint end_index = block->_nodes.size();
1567     // block->end_idx() not valid after PhaseRegAlloc
1568     for( uint instruction_index = 1; instruction_index < end_index; ++instruction_index ) {
1569       Node     *n = block->_nodes.at(instruction_index);
1570       if( n->is_Mach() ) {
1571         MachNode *m = n->as_Mach();
1572         int deleted_count = 0;
1573         // check for peephole opportunities
1574         MachNode *m2 = m->peephole( block, instruction_index, _regalloc, deleted_count, C );
1575         if( m2 != NULL ) {
1576 #ifndef PRODUCT
1577           if( PrintOptoPeephole ) {
1578             // Print method, first time only
1579             if( C->method() && method_name_not_printed ) {
1580               C->method()->print_short_name(); tty->cr();
1581               method_name_not_printed = false;
1582             }
1583             // Print this block
1584             if( Verbose && block_not_printed) {
1585               tty->print_cr("in block");
1586               block->dump();
1587               block_not_printed = false;
1588             }
1589             // Print instructions being deleted
1590             for( int i = (deleted_count - 1); i >= 0; --i ) {
1591               block->_nodes.at(instruction_index-i)->as_Mach()->format(_regalloc); tty->cr();
1592             }
1593             tty->print_cr("replaced with");
1594             // Print new instruction
1595             m2->format(_regalloc);
1596             tty->print("\n\n");
1597           }
1598 #endif
1599           // Remove old nodes from basic block and update instruction_index
1600           // (old nodes still exist and may have edges pointing to them
1601           //  as register allocation info is stored in the allocator using
1602           //  the node index to live range mappings.)
1603           uint safe_instruction_index = (instruction_index - deleted_count);
1604           for( ; (instruction_index > safe_instruction_index); --instruction_index ) {
1605             block->_nodes.remove( instruction_index );
1606           }
1607           // install new node after safe_instruction_index
1608           block->_nodes.insert( safe_instruction_index + 1, m2 );
1609           end_index = block->_nodes.size() - 1; // Recompute new block size
1610           NOT_PRODUCT( inc_peepholes(); )
1611         }
1612       }
1613     }
1614   }
1615 }
1616 
1617 //------------------------------print_statistics-------------------------------
1618 #ifndef PRODUCT
1619 void PhasePeephole::print_statistics() {
1620   tty->print_cr("Peephole: peephole rules applied: %d",  _total_peepholes);
1621 }
1622 #endif
1623 
1624 
1625 //=============================================================================
1626 //------------------------------set_req_X--------------------------------------
1627 void Node::set_req_X( uint i, Node *n, PhaseIterGVN *igvn ) {
1628   assert( is_not_dead(n), "can not use dead node");
1629   assert( igvn->hash_find(this) != this, "Need to remove from hash before changing edges" );
1630   Node *old = in(i);
1631   set_req(i, n);
1632 
1633   // old goes dead?
1634   if( old ) {
1635     switch (old->outcnt()) {
1636     case 0:
1637       // Put into the worklist to kill later. We do not kill it now because the
1638       // recursive kill will delete the current node (this) if dead-loop exists
1639       if (!old->is_top())
1640         igvn->_worklist.push( old );
1641       break;
1642     case 1:
1643       if( old->is_Store() || old->has_special_unique_user() )
1644         igvn->add_users_to_worklist( old );
1645       break;
1646     case 2:
1647       if( old->is_Store() )
1648         igvn->add_users_to_worklist( old );
1649       if( old->Opcode() == Op_Region )
1650         igvn->_worklist.push(old);
1651       break;
1652     case 3:
1653       if( old->Opcode() == Op_Region ) {
1654         igvn->_worklist.push(old);
1655         igvn->add_users_to_worklist( old );
1656       }
1657       break;
1658     default:
1659       break;
1660     }
1661   }
1662 
1663 }
1664 
1665 //-------------------------------replace_by-----------------------------------
1666 // Using def-use info, replace one node for another.  Follow the def-use info
1667 // to all users of the OLD node.  Then make all uses point to the NEW node.
1668 void Node::replace_by(Node *new_node) {
1669   assert(!is_top(), "top node has no DU info");
1670   for (DUIterator_Last imin, i = last_outs(imin); i >= imin; ) {
1671     Node* use = last_out(i);
1672     uint uses_found = 0;
1673     for (uint j = 0; j < use->len(); j++) {
1674       if (use->in(j) == this) {
1675         if (j < use->req())
1676               use->set_req(j, new_node);
1677         else  use->set_prec(j, new_node);
1678         uses_found++;
1679       }
1680     }
1681     i -= uses_found;    // we deleted 1 or more copies of this edge
1682   }
1683 }
1684 
1685 //=============================================================================
1686 //-----------------------------------------------------------------------------
1687 void Type_Array::grow( uint i ) {
1688   if( !_max ) {
1689     _max = 1;
1690     _types = (const Type**)_a->Amalloc( _max * sizeof(Type*) );
1691     _types[0] = NULL;
1692   }
1693   uint old = _max;
1694   while( i >= _max ) _max <<= 1;        // Double to fit
1695   _types = (const Type**)_a->Arealloc( _types, old*sizeof(Type*),_max*sizeof(Type*));
1696   memset( &_types[old], 0, (_max-old)*sizeof(Type*) );
1697 }
1698 
1699 //------------------------------dump-------------------------------------------
1700 #ifndef PRODUCT
1701 void Type_Array::dump() const {
1702   uint max = Size();
1703   for( uint i = 0; i < max; i++ ) {
1704     if( _types[i] != NULL ) {
1705       tty->print("  %d\t== ", i); _types[i]->dump(); tty->cr();
1706     }
1707   }
1708 }
1709 #endif