1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/barrierSet.hpp"
  27 #include "gc/shared/c2/barrierSetC2.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "memory/resourceArea.hpp"
  30 #include "opto/block.hpp"
  31 #include "opto/callnode.hpp"
  32 #include "opto/castnode.hpp"
  33 #include "opto/cfgnode.hpp"
  34 #include "opto/idealGraphPrinter.hpp"
  35 #include "opto/loopnode.hpp"
  36 #include "opto/machnode.hpp"
  37 #include "opto/opcodes.hpp"
  38 #include "opto/phaseX.hpp"
  39 #include "opto/regalloc.hpp"
  40 #include "opto/rootnode.hpp"
  41 #include "utilities/macros.hpp"
  42 
  43 //=============================================================================
  44 #define NODE_HASH_MINIMUM_SIZE    255
  45 //------------------------------NodeHash---------------------------------------
  46 NodeHash::NodeHash(uint est_max_size) :
  47   _a(Thread::current()->resource_area()),
  48   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
  49   _inserts(0), _insert_limit( insert_limit() ),
  50   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) ) // (Node**)_a->Amalloc(_max * sizeof(Node*)) ),
  51 #ifndef PRODUCT
  52   , _grows(0),_look_probes(0), _lookup_hits(0), _lookup_misses(0),
  53   _insert_probes(0), _delete_probes(0), _delete_hits(0), _delete_misses(0),
  54    _total_inserts(0), _total_insert_probes(0)
  55 #endif
  56 {
  57   // _sentinel must be in the current node space
  58   _sentinel = new ProjNode(NULL, TypeFunc::Control);
  59   memset(_table,0,sizeof(Node*)*_max);
  60 }
  61 
  62 //------------------------------NodeHash---------------------------------------
  63 NodeHash::NodeHash(Arena *arena, uint est_max_size) :
  64   _a(arena),
  65   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
  66   _inserts(0), _insert_limit( insert_limit() ),
  67   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) )
  68 #ifndef PRODUCT
  69   , _grows(0),_look_probes(0), _lookup_hits(0), _lookup_misses(0),
  70   _insert_probes(0), _delete_probes(0), _delete_hits(0), _delete_misses(0),
  71    _total_inserts(0), _total_insert_probes(0)
  72 #endif
  73 {
  74   // _sentinel must be in the current node space
  75   _sentinel = new ProjNode(NULL, TypeFunc::Control);
  76   memset(_table,0,sizeof(Node*)*_max);
  77 }
  78 
  79 //------------------------------NodeHash---------------------------------------
  80 NodeHash::NodeHash(NodeHash *nh) {
  81   debug_only(_table = (Node**)badAddress);   // interact correctly w/ operator=
  82   // just copy in all the fields
  83   *this = *nh;
  84   // nh->_sentinel must be in the current node space
  85 }
  86 
  87 void NodeHash::replace_with(NodeHash *nh) {
  88   debug_only(_table = (Node**)badAddress);   // interact correctly w/ operator=
  89   // just copy in all the fields
  90   *this = *nh;
  91   // nh->_sentinel must be in the current node space
  92 }
  93 
  94 //------------------------------hash_find--------------------------------------
  95 // Find in hash table
  96 Node *NodeHash::hash_find( const Node *n ) {
  97   // ((Node*)n)->set_hash( n->hash() );
  98   uint hash = n->hash();
  99   if (hash == Node::NO_HASH) {
 100     NOT_PRODUCT( _lookup_misses++ );
 101     return NULL;
 102   }
 103   uint key = hash & (_max-1);
 104   uint stride = key | 0x01;
 105   NOT_PRODUCT( _look_probes++ );
 106   Node *k = _table[key];        // Get hashed value
 107   if( !k ) {                    // ?Miss?
 108     NOT_PRODUCT( _lookup_misses++ );
 109     return NULL;                // Miss!
 110   }
 111 
 112   int op = n->Opcode();
 113   uint req = n->req();
 114   while( 1 ) {                  // While probing hash table
 115     if( k->req() == req &&      // Same count of inputs
 116         k->Opcode() == op ) {   // Same Opcode
 117       for( uint i=0; i<req; i++ )
 118         if( n->in(i)!=k->in(i)) // Different inputs?
 119           goto collision;       // "goto" is a speed hack...
 120       if( n->cmp(*k) ) {        // Check for any special bits
 121         NOT_PRODUCT( _lookup_hits++ );
 122         return k;               // Hit!
 123       }
 124     }
 125   collision:
 126     NOT_PRODUCT( _look_probes++ );
 127     key = (key + stride/*7*/) & (_max-1); // Stride through table with relative prime
 128     k = _table[key];            // Get hashed value
 129     if( !k ) {                  // ?Miss?
 130       NOT_PRODUCT( _lookup_misses++ );
 131       return NULL;              // Miss!
 132     }
 133   }
 134   ShouldNotReachHere();
 135   return NULL;
 136 }
 137 
 138 //------------------------------hash_find_insert-------------------------------
 139 // Find in hash table, insert if not already present
 140 // Used to preserve unique entries in hash table
 141 Node *NodeHash::hash_find_insert( Node *n ) {
 142   // n->set_hash( );
 143   uint hash = n->hash();
 144   if (hash == Node::NO_HASH) {
 145     NOT_PRODUCT( _lookup_misses++ );
 146     return NULL;
 147   }
 148   uint key = hash & (_max-1);
 149   uint stride = key | 0x01;     // stride must be relatively prime to table siz
 150   uint first_sentinel = 0;      // replace a sentinel if seen.
 151   NOT_PRODUCT( _look_probes++ );
 152   Node *k = _table[key];        // Get hashed value
 153   if( !k ) {                    // ?Miss?
 154     NOT_PRODUCT( _lookup_misses++ );
 155     _table[key] = n;            // Insert into table!
 156     debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 157     check_grow();               // Grow table if insert hit limit
 158     return NULL;                // Miss!
 159   }
 160   else if( k == _sentinel ) {
 161     first_sentinel = key;      // Can insert here
 162   }
 163 
 164   int op = n->Opcode();
 165   uint req = n->req();
 166   while( 1 ) {                  // While probing hash table
 167     if( k->req() == req &&      // Same count of inputs
 168         k->Opcode() == op ) {   // Same Opcode
 169       for( uint i=0; i<req; i++ )
 170         if( n->in(i)!=k->in(i)) // Different inputs?
 171           goto collision;       // "goto" is a speed hack...
 172       if( n->cmp(*k) ) {        // Check for any special bits
 173         NOT_PRODUCT( _lookup_hits++ );
 174         return k;               // Hit!
 175       }
 176     }
 177   collision:
 178     NOT_PRODUCT( _look_probes++ );
 179     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
 180     k = _table[key];            // Get hashed value
 181     if( !k ) {                  // ?Miss?
 182       NOT_PRODUCT( _lookup_misses++ );
 183       key = (first_sentinel == 0) ? key : first_sentinel; // ?saw sentinel?
 184       _table[key] = n;          // Insert into table!
 185       debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 186       check_grow();             // Grow table if insert hit limit
 187       return NULL;              // Miss!
 188     }
 189     else if( first_sentinel == 0 && k == _sentinel ) {
 190       first_sentinel = key;    // Can insert here
 191     }
 192 
 193   }
 194   ShouldNotReachHere();
 195   return NULL;
 196 }
 197 
 198 //------------------------------hash_insert------------------------------------
 199 // Insert into hash table
 200 void NodeHash::hash_insert( Node *n ) {
 201   // // "conflict" comments -- print nodes that conflict
 202   // bool conflict = false;
 203   // n->set_hash();
 204   uint hash = n->hash();
 205   if (hash == Node::NO_HASH) {
 206     return;
 207   }
 208   check_grow();
 209   uint key = hash & (_max-1);
 210   uint stride = key | 0x01;
 211 
 212   while( 1 ) {                  // While probing hash table
 213     NOT_PRODUCT( _insert_probes++ );
 214     Node *k = _table[key];      // Get hashed value
 215     if( !k || (k == _sentinel) ) break;       // Found a slot
 216     assert( k != n, "already inserted" );
 217     // if( PrintCompilation && PrintOptoStatistics && Verbose ) { tty->print("  conflict: "); k->dump(); conflict = true; }
 218     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
 219   }
 220   _table[key] = n;              // Insert into table!
 221   debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
 222   // if( conflict ) { n->dump(); }
 223 }
 224 
 225 //------------------------------hash_delete------------------------------------
 226 // Replace in hash table with sentinel
 227 bool NodeHash::hash_delete( const Node *n ) {
 228   Node *k;
 229   uint hash = n->hash();
 230   if (hash == Node::NO_HASH) {
 231     NOT_PRODUCT( _delete_misses++ );
 232     return false;
 233   }
 234   uint key = hash & (_max-1);
 235   uint stride = key | 0x01;
 236   debug_only( uint counter = 0; );
 237   for( ; /* (k != NULL) && (k != _sentinel) */; ) {
 238     debug_only( counter++ );
 239     NOT_PRODUCT( _delete_probes++ );
 240     k = _table[key];            // Get hashed value
 241     if( !k ) {                  // Miss?
 242       NOT_PRODUCT( _delete_misses++ );
 243 #ifdef ASSERT
 244       if( VerifyOpto ) {
 245         for( uint i=0; i < _max; i++ )
 246           assert( _table[i] != n, "changed edges with rehashing" );
 247       }
 248 #endif
 249       return false;             // Miss! Not in chain
 250     }
 251     else if( n == k ) {
 252       NOT_PRODUCT( _delete_hits++ );
 253       _table[key] = _sentinel;  // Hit! Label as deleted entry
 254       debug_only(((Node*)n)->exit_hash_lock()); // Unlock the node upon removal from table.
 255       return true;
 256     }
 257     else {
 258       // collision: move through table with prime offset
 259       key = (key + stride/*7*/) & (_max-1);
 260       assert( counter <= _insert_limit, "Cycle in hash-table");
 261     }
 262   }
 263   ShouldNotReachHere();
 264   return false;
 265 }
 266 
 267 //------------------------------round_up---------------------------------------
 268 // Round up to nearest power of 2
 269 uint NodeHash::round_up( uint x ) {
 270   x += (x>>2);                  // Add 25% slop
 271   if( x <16 ) return 16;        // Small stuff
 272   uint i=16;
 273   while( i < x ) i <<= 1;       // Double to fit
 274   return i;                     // Return hash table size
 275 }
 276 
 277 //------------------------------grow-------------------------------------------
 278 // Grow _table to next power of 2 and insert old entries
 279 void  NodeHash::grow() {
 280   // Record old state
 281   uint   old_max   = _max;
 282   Node **old_table = _table;
 283   // Construct new table with twice the space
 284 #ifndef PRODUCT
 285   _grows++;
 286   _total_inserts       += _inserts;
 287   _total_insert_probes += _insert_probes;
 288   _insert_probes   = 0;
 289 #endif
 290   _inserts         = 0;
 291   _max     = _max << 1;
 292   _table   = NEW_ARENA_ARRAY( _a , Node* , _max ); // (Node**)_a->Amalloc( _max * sizeof(Node*) );
 293   memset(_table,0,sizeof(Node*)*_max);
 294   _insert_limit = insert_limit();
 295   // Insert old entries into the new table
 296   for( uint i = 0; i < old_max; i++ ) {
 297     Node *m = *old_table++;
 298     if( !m || m == _sentinel ) continue;
 299     debug_only(m->exit_hash_lock()); // Unlock the node upon removal from old table.
 300     hash_insert(m);
 301   }
 302 }
 303 
 304 //------------------------------clear------------------------------------------
 305 // Clear all entries in _table to NULL but keep storage
 306 void  NodeHash::clear() {
 307 #ifdef ASSERT
 308   // Unlock all nodes upon removal from table.
 309   for (uint i = 0; i < _max; i++) {
 310     Node* n = _table[i];
 311     if (!n || n == _sentinel)  continue;
 312     n->exit_hash_lock();
 313   }
 314 #endif
 315 
 316   memset( _table, 0, _max * sizeof(Node*) );
 317 }
 318 
 319 //-----------------------remove_useless_nodes----------------------------------
 320 // Remove useless nodes from value table,
 321 // implementation does not depend on hash function
 322 void NodeHash::remove_useless_nodes(VectorSet &useful) {
 323 
 324   // Dead nodes in the hash table inherited from GVN should not replace
 325   // existing nodes, remove dead nodes.
 326   uint max = size();
 327   Node *sentinel_node = sentinel();
 328   for( uint i = 0; i < max; ++i ) {
 329     Node *n = at(i);
 330     if(n != NULL && n != sentinel_node && !useful.test(n->_idx)) {
 331       debug_only(n->exit_hash_lock()); // Unlock the node when removed
 332       _table[i] = sentinel_node;       // Replace with placeholder
 333     }
 334   }
 335 }
 336 
 337 
 338 void NodeHash::check_no_speculative_types() {
 339 #ifdef ASSERT
 340   uint max = size();
 341   Node *sentinel_node = sentinel();
 342   for (uint i = 0; i < max; ++i) {
 343     Node *n = at(i);
 344     if(n != NULL && n != sentinel_node && n->is_Type() && n->outcnt() > 0) {
 345       TypeNode* tn = n->as_Type();
 346       const Type* t = tn->type();
 347       const Type* t_no_spec = t->remove_speculative();
 348       assert(t == t_no_spec, "dead node in hash table or missed node during speculative cleanup");
 349     }
 350   }
 351 #endif
 352 }
 353 
 354 #ifndef PRODUCT
 355 //------------------------------dump-------------------------------------------
 356 // Dump statistics for the hash table
 357 void NodeHash::dump() {
 358   _total_inserts       += _inserts;
 359   _total_insert_probes += _insert_probes;
 360   if (PrintCompilation && PrintOptoStatistics && Verbose && (_inserts > 0)) {
 361     if (WizardMode) {
 362       for (uint i=0; i<_max; i++) {
 363         if (_table[i])
 364           tty->print("%d/%d/%d ",i,_table[i]->hash()&(_max-1),_table[i]->_idx);
 365       }
 366     }
 367     tty->print("\nGVN Hash stats:  %d grows to %d max_size\n", _grows, _max);
 368     tty->print("  %d/%d (%8.1f%% full)\n", _inserts, _max, (double)_inserts/_max*100.0);
 369     tty->print("  %dp/(%dh+%dm) (%8.2f probes/lookup)\n", _look_probes, _lookup_hits, _lookup_misses, (double)_look_probes/(_lookup_hits+_lookup_misses));
 370     tty->print("  %dp/%di (%8.2f probes/insert)\n", _total_insert_probes, _total_inserts, (double)_total_insert_probes/_total_inserts);
 371     // sentinels increase lookup cost, but not insert cost
 372     assert((_lookup_misses+_lookup_hits)*4+100 >= _look_probes, "bad hash function");
 373     assert( _inserts+(_inserts>>3) < _max, "table too full" );
 374     assert( _inserts*3+100 >= _insert_probes, "bad hash function" );
 375   }
 376 }
 377 
 378 Node *NodeHash::find_index(uint idx) { // For debugging
 379   // Find an entry by its index value
 380   for( uint i = 0; i < _max; i++ ) {
 381     Node *m = _table[i];
 382     if( !m || m == _sentinel ) continue;
 383     if( m->_idx == (uint)idx ) return m;
 384   }
 385   return NULL;
 386 }
 387 #endif
 388 
 389 #ifdef ASSERT
 390 NodeHash::~NodeHash() {
 391   // Unlock all nodes upon destruction of table.
 392   if (_table != (Node**)badAddress)  clear();
 393 }
 394 
 395 void NodeHash::operator=(const NodeHash& nh) {
 396   // Unlock all nodes upon replacement of table.
 397   if (&nh == this)  return;
 398   if (_table != (Node**)badAddress)  clear();
 399   memcpy((void*)this, (void*)&nh, sizeof(*this));
 400   // Do not increment hash_lock counts again.
 401   // Instead, be sure we never again use the source table.
 402   ((NodeHash*)&nh)->_table = (Node**)badAddress;
 403 }
 404 
 405 
 406 #endif
 407 
 408 
 409 //=============================================================================
 410 //------------------------------PhaseRemoveUseless-----------------------------
 411 // 1) Use a breadthfirst walk to collect useful nodes reachable from root.
 412 PhaseRemoveUseless::PhaseRemoveUseless(PhaseGVN *gvn, Unique_Node_List *worklist, PhaseNumber phase_num) : Phase(phase_num),
 413   _useful(Thread::current()->resource_area()) {
 414 
 415   // Implementation requires 'UseLoopSafepoints == true' and an edge from root
 416   // to each SafePointNode at a backward branch.  Inserted in add_safepoint().
 417   if( !UseLoopSafepoints || !OptoRemoveUseless ) return;
 418 
 419   // Identify nodes that are reachable from below, useful.
 420   C->identify_useful_nodes(_useful);
 421   // Update dead node list
 422   C->update_dead_node_list(_useful);
 423 
 424   // Remove all useless nodes from PhaseValues' recorded types
 425   // Must be done before disconnecting nodes to preserve hash-table-invariant
 426   gvn->remove_useless_nodes(_useful.member_set());
 427 
 428   // Remove all useless nodes from future worklist
 429   worklist->remove_useless_nodes(_useful.member_set());
 430 
 431   // Disconnect 'useless' nodes that are adjacent to useful nodes
 432   C->remove_useless_nodes(_useful);
 433 
 434   // Remove edges from "root" to each SafePoint at a backward branch.
 435   // They were inserted during parsing (see add_safepoint()) to make infinite
 436   // loops without calls or exceptions visible to root, i.e., useful.
 437   Node *root = C->root();
 438   if( root != NULL ) {
 439     for( uint i = root->req(); i < root->len(); ++i ) {
 440       Node *n = root->in(i);
 441       if( n != NULL && n->is_SafePoint() ) {
 442         root->rm_prec(i);
 443         --i;
 444       }
 445     }
 446   }
 447 }
 448 
 449 //=============================================================================
 450 //------------------------------PhaseRenumberLive------------------------------
 451 // First, remove useless nodes (equivalent to identifying live nodes).
 452 // Then, renumber live nodes.
 453 //
 454 // The set of live nodes is returned by PhaseRemoveUseless in the _useful structure.
 455 // If the number of live nodes is 'x' (where 'x' == _useful.size()), then the
 456 // PhaseRenumberLive updates the node ID of each node (the _idx field) with a unique
 457 // value in the range [0, x).
 458 //
 459 // At the end of the PhaseRenumberLive phase, the compiler's count of unique nodes is
 460 // updated to 'x' and the list of dead nodes is reset (as there are no dead nodes).
 461 //
 462 // The PhaseRenumberLive phase updates two data structures with the new node IDs.
 463 // (1) The worklist is used by the PhaseIterGVN phase to identify nodes that must be
 464 // processed. A new worklist (with the updated node IDs) is returned in 'new_worklist'.
 465 // (2) Type information (the field PhaseGVN::_types) maps type information to each
 466 // node ID. The mapping is updated to use the new node IDs as well. Updated type
 467 // information is returned in PhaseGVN::_types.
 468 //
 469 // The PhaseRenumberLive phase does not preserve the order of elements in the worklist.
 470 //
 471 // Other data structures used by the compiler are not updated. The hash table for value
 472 // numbering (the field PhaseGVN::_table) is not updated because computing the hash
 473 // values is not based on node IDs. The field PhaseGVN::_nodes is not updated either
 474 // because it is empty wherever PhaseRenumberLive is used.
 475 PhaseRenumberLive::PhaseRenumberLive(PhaseGVN* gvn,
 476                                      Unique_Node_List* worklist, Unique_Node_List* new_worklist,
 477                                      PhaseNumber phase_num) :
 478   PhaseRemoveUseless(gvn, worklist, Remove_Useless_And_Renumber_Live) {
 479 
 480   assert(RenumberLiveNodes, "RenumberLiveNodes must be set to true for node renumbering to take place");
 481   assert(C->live_nodes() == _useful.size(), "the number of live nodes must match the number of useful nodes");
 482   assert(gvn->nodes_size() == 0, "GVN must not contain any nodes at this point");
 483 
 484   uint old_unique_count = C->unique();
 485   uint live_node_count = C->live_nodes();
 486   uint worklist_size = worklist->size();
 487 
 488   // Storage for the updated type information.
 489   Type_Array new_type_array(C->comp_arena());
 490 
 491   // Iterate over the set of live nodes.
 492   uint current_idx = 0; // The current new node ID. Incremented after every assignment.
 493   for (uint i = 0; i < _useful.size(); i++) {
 494     Node* n = _useful.at(i);
 495     // Sanity check that fails if we ever decide to execute this phase after EA
 496     assert(!n->is_Phi() || n->as_Phi()->inst_mem_id() == -1, "should not be linked to data Phi");
 497     const Type* type = gvn->type_or_null(n);
 498     new_type_array.map(current_idx, type);
 499 
 500     bool in_worklist = false;
 501     if (worklist->member(n)) {
 502       in_worklist = true;
 503     }
 504 
 505     n->set_idx(current_idx); // Update node ID.
 506 
 507     if (in_worklist) {
 508       new_worklist->push(n);
 509     }
 510 
 511     current_idx++;
 512   }
 513 
 514   assert(worklist_size == new_worklist->size(), "the new worklist must have the same size as the original worklist");
 515   assert(live_node_count == current_idx, "all live nodes must be processed");
 516 
 517   // Replace the compiler's type information with the updated type information.
 518   gvn->replace_types(new_type_array);
 519 
 520   // Update the unique node count of the compilation to the number of currently live nodes.
 521   C->set_unique(live_node_count);
 522 
 523   // Set the dead node count to 0 and reset dead node list.
 524   C->reset_dead_node_list();
 525 }
 526 
 527 
 528 //=============================================================================
 529 //------------------------------PhaseTransform---------------------------------
 530 PhaseTransform::PhaseTransform( PhaseNumber pnum ) : Phase(pnum),
 531   _arena(Thread::current()->resource_area()),
 532   _nodes(_arena),
 533   _types(_arena)
 534 {
 535   init_con_caches();
 536 #ifndef PRODUCT
 537   clear_progress();
 538   clear_transforms();
 539   set_allow_progress(true);
 540 #endif
 541   // Force allocation for currently existing nodes
 542   _types.map(C->unique(), NULL);
 543 }
 544 
 545 //------------------------------PhaseTransform---------------------------------
 546 PhaseTransform::PhaseTransform( Arena *arena, PhaseNumber pnum ) : Phase(pnum),
 547   _arena(arena),
 548   _nodes(arena),
 549   _types(arena)
 550 {
 551   init_con_caches();
 552 #ifndef PRODUCT
 553   clear_progress();
 554   clear_transforms();
 555   set_allow_progress(true);
 556 #endif
 557   // Force allocation for currently existing nodes
 558   _types.map(C->unique(), NULL);
 559 }
 560 
 561 //------------------------------PhaseTransform---------------------------------
 562 // Initialize with previously generated type information
 563 PhaseTransform::PhaseTransform( PhaseTransform *pt, PhaseNumber pnum ) : Phase(pnum),
 564   _arena(pt->_arena),
 565   _nodes(pt->_nodes),
 566   _types(pt->_types)
 567 {
 568   init_con_caches();
 569 #ifndef PRODUCT
 570   clear_progress();
 571   clear_transforms();
 572   set_allow_progress(true);
 573 #endif
 574 }
 575 
 576 void PhaseTransform::init_con_caches() {
 577   memset(_icons,0,sizeof(_icons));
 578   memset(_lcons,0,sizeof(_lcons));
 579   memset(_zcons,0,sizeof(_zcons));
 580 }
 581 
 582 
 583 //--------------------------------find_int_type--------------------------------
 584 const TypeInt* PhaseTransform::find_int_type(Node* n) {
 585   if (n == NULL)  return NULL;
 586   // Call type_or_null(n) to determine node's type since we might be in
 587   // parse phase and call n->Value() may return wrong type.
 588   // (For example, a phi node at the beginning of loop parsing is not ready.)
 589   const Type* t = type_or_null(n);
 590   if (t == NULL)  return NULL;
 591   return t->isa_int();
 592 }
 593 
 594 
 595 //-------------------------------find_long_type--------------------------------
 596 const TypeLong* PhaseTransform::find_long_type(Node* n) {
 597   if (n == NULL)  return NULL;
 598   // (See comment above on type_or_null.)
 599   const Type* t = type_or_null(n);
 600   if (t == NULL)  return NULL;
 601   return t->isa_long();
 602 }
 603 
 604 
 605 #ifndef PRODUCT
 606 void PhaseTransform::dump_old2new_map() const {
 607   _nodes.dump();
 608 }
 609 
 610 void PhaseTransform::dump_new( uint nidx ) const {
 611   for( uint i=0; i<_nodes.Size(); i++ )
 612     if( _nodes[i] && _nodes[i]->_idx == nidx ) {
 613       _nodes[i]->dump();
 614       tty->cr();
 615       tty->print_cr("Old index= %d",i);
 616       return;
 617     }
 618   tty->print_cr("Node %d not found in the new indices", nidx);
 619 }
 620 
 621 //------------------------------dump_types-------------------------------------
 622 void PhaseTransform::dump_types( ) const {
 623   _types.dump();
 624 }
 625 
 626 //------------------------------dump_nodes_and_types---------------------------
 627 void PhaseTransform::dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl) {
 628   VectorSet visited(Thread::current()->resource_area());
 629   dump_nodes_and_types_recur( root, depth, only_ctrl, visited );
 630 }
 631 
 632 //------------------------------dump_nodes_and_types_recur---------------------
 633 void PhaseTransform::dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited) {
 634   if( !n ) return;
 635   if( depth == 0 ) return;
 636   if( visited.test_set(n->_idx) ) return;
 637   for( uint i=0; i<n->len(); i++ ) {
 638     if( only_ctrl && !(n->is_Region()) && i != TypeFunc::Control ) continue;
 639     dump_nodes_and_types_recur( n->in(i), depth-1, only_ctrl, visited );
 640   }
 641   n->dump();
 642   if (type_or_null(n) != NULL) {
 643     tty->print("      "); type(n)->dump(); tty->cr();
 644   }
 645 }
 646 
 647 #endif
 648 
 649 
 650 //=============================================================================
 651 //------------------------------PhaseValues------------------------------------
 652 // Set minimum table size to "255"
 653 PhaseValues::PhaseValues( Arena *arena, uint est_max_size ) : PhaseTransform(arena, GVN), _table(arena, est_max_size) {
 654   NOT_PRODUCT( clear_new_values(); )
 655 }
 656 
 657 //------------------------------PhaseValues------------------------------------
 658 // Set minimum table size to "255"
 659 PhaseValues::PhaseValues( PhaseValues *ptv ) : PhaseTransform( ptv, GVN ),
 660   _table(&ptv->_table) {
 661   NOT_PRODUCT( clear_new_values(); )
 662 }
 663 
 664 //------------------------------PhaseValues------------------------------------
 665 // Used by +VerifyOpto.  Clear out hash table but copy _types array.
 666 PhaseValues::PhaseValues( PhaseValues *ptv, const char *dummy ) : PhaseTransform( ptv, GVN ),
 667   _table(ptv->arena(),ptv->_table.size()) {
 668   NOT_PRODUCT( clear_new_values(); )
 669 }
 670 
 671 //------------------------------~PhaseValues-----------------------------------
 672 #ifndef PRODUCT
 673 PhaseValues::~PhaseValues() {
 674   _table.dump();
 675 
 676   // Statistics for value progress and efficiency
 677   if( PrintCompilation && Verbose && WizardMode ) {
 678     tty->print("\n%sValues: %d nodes ---> %d/%d (%d)",
 679       is_IterGVN() ? "Iter" : "    ", C->unique(), made_progress(), made_transforms(), made_new_values());
 680     if( made_transforms() != 0 ) {
 681       tty->print_cr("  ratio %f", made_progress()/(float)made_transforms() );
 682     } else {
 683       tty->cr();
 684     }
 685   }
 686 }
 687 #endif
 688 
 689 //------------------------------makecon----------------------------------------
 690 ConNode* PhaseTransform::makecon(const Type *t) {
 691   assert(t->singleton(), "must be a constant");
 692   assert(!t->empty() || t == Type::TOP, "must not be vacuous range");
 693   switch (t->base()) {  // fast paths
 694   case Type::Half:
 695   case Type::Top:  return (ConNode*) C->top();
 696   case Type::Int:  return intcon( t->is_int()->get_con() );
 697   case Type::Long: return longcon( t->is_long()->get_con() );
 698   default:         break;
 699   }
 700   if (t->is_zero_type())
 701     return zerocon(t->basic_type());
 702   return uncached_makecon(t);
 703 }
 704 
 705 //--------------------------uncached_makecon-----------------------------------
 706 // Make an idealized constant - one of ConINode, ConPNode, etc.
 707 ConNode* PhaseValues::uncached_makecon(const Type *t) {
 708   assert(t->singleton(), "must be a constant");
 709   ConNode* x = ConNode::make(t);
 710   ConNode* k = (ConNode*)hash_find_insert(x); // Value numbering
 711   if (k == NULL) {
 712     set_type(x, t);             // Missed, provide type mapping
 713     GrowableArray<Node_Notes*>* nna = C->node_note_array();
 714     if (nna != NULL) {
 715       Node_Notes* loc = C->locate_node_notes(nna, x->_idx, true);
 716       loc->clear(); // do not put debug info on constants
 717     }
 718   } else {
 719     x->destruct();              // Hit, destroy duplicate constant
 720     x = k;                      // use existing constant
 721   }
 722   return x;
 723 }
 724 
 725 //------------------------------intcon-----------------------------------------
 726 // Fast integer constant.  Same as "transform(new ConINode(TypeInt::make(i)))"
 727 ConINode* PhaseTransform::intcon(jint i) {
 728   // Small integer?  Check cache! Check that cached node is not dead
 729   if (i >= _icon_min && i <= _icon_max) {
 730     ConINode* icon = _icons[i-_icon_min];
 731     if (icon != NULL && icon->in(TypeFunc::Control) != NULL)
 732       return icon;
 733   }
 734   ConINode* icon = (ConINode*) uncached_makecon(TypeInt::make(i));
 735   assert(icon->is_Con(), "");
 736   if (i >= _icon_min && i <= _icon_max)
 737     _icons[i-_icon_min] = icon;   // Cache small integers
 738   return icon;
 739 }
 740 
 741 //------------------------------longcon----------------------------------------
 742 // Fast long constant.
 743 ConLNode* PhaseTransform::longcon(jlong l) {
 744   // Small integer?  Check cache! Check that cached node is not dead
 745   if (l >= _lcon_min && l <= _lcon_max) {
 746     ConLNode* lcon = _lcons[l-_lcon_min];
 747     if (lcon != NULL && lcon->in(TypeFunc::Control) != NULL)
 748       return lcon;
 749   }
 750   ConLNode* lcon = (ConLNode*) uncached_makecon(TypeLong::make(l));
 751   assert(lcon->is_Con(), "");
 752   if (l >= _lcon_min && l <= _lcon_max)
 753     _lcons[l-_lcon_min] = lcon;      // Cache small integers
 754   return lcon;
 755 }
 756 
 757 //------------------------------zerocon-----------------------------------------
 758 // Fast zero or null constant. Same as "transform(ConNode::make(Type::get_zero_type(bt)))"
 759 ConNode* PhaseTransform::zerocon(BasicType bt) {
 760   assert((uint)bt <= _zcon_max, "domain check");
 761   ConNode* zcon = _zcons[bt];
 762   if (zcon != NULL && zcon->in(TypeFunc::Control) != NULL)
 763     return zcon;
 764   zcon = (ConNode*) uncached_makecon(Type::get_zero_type(bt));
 765   _zcons[bt] = zcon;
 766   return zcon;
 767 }
 768 
 769 
 770 
 771 //=============================================================================
 772 //------------------------------transform--------------------------------------
 773 // Return a node which computes the same function as this node, but in a
 774 // faster or cheaper fashion.
 775 Node *PhaseGVN::transform( Node *n ) {
 776   return transform_no_reclaim(n);
 777 }
 778 
 779 //------------------------------transform--------------------------------------
 780 // Return a node which computes the same function as this node, but
 781 // in a faster or cheaper fashion.
 782 Node *PhaseGVN::transform_no_reclaim( Node *n ) {
 783   NOT_PRODUCT( set_transforms(); )
 784 
 785   // Apply the Ideal call in a loop until it no longer applies
 786   Node *k = n;
 787   NOT_PRODUCT( uint loop_count = 0; )
 788   while( 1 ) {
 789     Node *i = k->Ideal(this, /*can_reshape=*/false);
 790     if( !i ) break;
 791     assert( i->_idx >= k->_idx, "Idealize should return new nodes, use Identity to return old nodes" );
 792     k = i;
 793     assert(loop_count++ < K, "infinite loop in PhaseGVN::transform");
 794   }
 795   NOT_PRODUCT( if( loop_count != 0 ) { set_progress(); } )
 796 
 797 
 798   // If brand new node, make space in type array.
 799   ensure_type_or_null(k);
 800 
 801   // Since I just called 'Value' to compute the set of run-time values
 802   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
 803   // cache Value.  Later requests for the local phase->type of this Node can
 804   // use the cached Value instead of suffering with 'bottom_type'.
 805   const Type *t = k->Value(this); // Get runtime Value set
 806   assert(t != NULL, "value sanity");
 807   if (type_or_null(k) != t) {
 808 #ifndef PRODUCT
 809     // Do not count initial visit to node as a transformation
 810     if (type_or_null(k) == NULL) {
 811       inc_new_values();
 812       set_progress();
 813     }
 814 #endif
 815     set_type(k, t);
 816     // If k is a TypeNode, capture any more-precise type permanently into Node
 817     k->raise_bottom_type(t);
 818   }
 819 
 820   if( t->singleton() && !k->is_Con() ) {
 821     NOT_PRODUCT( set_progress(); )
 822     return makecon(t);          // Turn into a constant
 823   }
 824 
 825   // Now check for Identities
 826   Node *i = k->Identity(this);  // Look for a nearby replacement
 827   if( i != k ) {                // Found? Return replacement!
 828     NOT_PRODUCT( set_progress(); )
 829     return i;
 830   }
 831 
 832   // Global Value Numbering
 833   i = hash_find_insert(k);      // Insert if new
 834   if( i && (i != k) ) {
 835     // Return the pre-existing node
 836     NOT_PRODUCT( set_progress(); )
 837     return i;
 838   }
 839 
 840   // Return Idealized original
 841   return k;
 842 }
 843 
 844 bool PhaseGVN::is_dominator_helper(Node *d, Node *n, bool linear_only) {
 845   if (d->is_top() || n->is_top()) {
 846     return false;
 847   }
 848   assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
 849   int i = 0;
 850   while (d != n) {
 851     n = IfNode::up_one_dom(n, linear_only);
 852     i++;
 853     if (n == NULL || i >= 10) {
 854       return false;
 855     }
 856   }
 857   return true;
 858 }
 859 
 860 #ifdef ASSERT
 861 //------------------------------dead_loop_check--------------------------------
 862 // Check for a simple dead loop when a data node references itself directly
 863 // or through an other data node excluding cons and phis.
 864 void PhaseGVN::dead_loop_check( Node *n ) {
 865   // Phi may reference itself in a loop
 866   if (n != NULL && !n->is_dead_loop_safe() && !n->is_CFG()) {
 867     // Do 2 levels check and only data inputs.
 868     bool no_dead_loop = true;
 869     uint cnt = n->req();
 870     for (uint i = 1; i < cnt && no_dead_loop; i++) {
 871       Node *in = n->in(i);
 872       if (in == n) {
 873         no_dead_loop = false;
 874       } else if (in != NULL && !in->is_dead_loop_safe()) {
 875         uint icnt = in->req();
 876         for (uint j = 1; j < icnt && no_dead_loop; j++) {
 877           if (in->in(j) == n || in->in(j) == in)
 878             no_dead_loop = false;
 879         }
 880       }
 881     }
 882     if (!no_dead_loop) n->dump(3);
 883     assert(no_dead_loop, "dead loop detected");
 884   }
 885 }
 886 #endif
 887 
 888 //=============================================================================
 889 //------------------------------PhaseIterGVN-----------------------------------
 890 // Initialize hash table to fresh and clean for +VerifyOpto
 891 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn, const char *dummy ) : PhaseGVN(igvn,dummy),
 892                                                                       _delay_transform(false),
 893                                                                       _stack(C->live_nodes() >> 1),
 894                                                                       _worklist( ) {
 895 }
 896 
 897 //------------------------------PhaseIterGVN-----------------------------------
 898 // Initialize with previous PhaseIterGVN info; used by PhaseCCP
 899 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn ) : PhaseGVN(igvn),
 900                                                    _delay_transform(igvn->_delay_transform),
 901                                                    _stack( igvn->_stack ),
 902                                                    _worklist( igvn->_worklist )
 903 {
 904 }
 905 
 906 //------------------------------PhaseIterGVN-----------------------------------
 907 // Initialize with previous PhaseGVN info from Parser
 908 PhaseIterGVN::PhaseIterGVN( PhaseGVN *gvn ) : PhaseGVN(gvn),
 909                                               _delay_transform(false),
 910 // TODO: Before incremental inlining it was allocated only once and it was fine. Now that
 911 //       the constructor is used in incremental inlining, this consumes too much memory:
 912 //                                            _stack(C->live_nodes() >> 1),
 913 //       So, as a band-aid, we replace this by:
 914                                               _stack(C->comp_arena(), 32),
 915                                               _worklist(*C->for_igvn())
 916 {
 917   uint max;
 918 
 919   // Dead nodes in the hash table inherited from GVN were not treated as
 920   // roots during def-use info creation; hence they represent an invisible
 921   // use.  Clear them out.
 922   max = _table.size();
 923   for( uint i = 0; i < max; ++i ) {
 924     Node *n = _table.at(i);
 925     if(n != NULL && n != _table.sentinel() && n->outcnt() == 0) {
 926       if( n->is_top() ) continue;
 927       assert( false, "Parse::remove_useless_nodes missed this node");
 928       hash_delete(n);
 929     }
 930   }
 931 
 932   // Any Phis or Regions on the worklist probably had uses that could not
 933   // make more progress because the uses were made while the Phis and Regions
 934   // were in half-built states.  Put all uses of Phis and Regions on worklist.
 935   max = _worklist.size();
 936   for( uint j = 0; j < max; j++ ) {
 937     Node *n = _worklist.at(j);
 938     uint uop = n->Opcode();
 939     if( uop == Op_Phi || uop == Op_Region ||
 940         n->is_Type() ||
 941         n->is_Mem() )
 942       add_users_to_worklist(n);
 943   }
 944 
 945   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 946   bs->add_users_to_worklist(&_worklist);
 947 }
 948 
 949 /**
 950  * Initialize worklist for each node.
 951  */
 952 void PhaseIterGVN::init_worklist(Node* first) {
 953   Unique_Node_List to_process;
 954   to_process.push(first);
 955 
 956   while (to_process.size() > 0) {
 957     Node* n = to_process.pop();
 958     if (!_worklist.member(n)) {
 959       _worklist.push(n);
 960 
 961       uint cnt = n->req();
 962       for(uint i = 0; i < cnt; i++) {
 963         Node* m = n->in(i);
 964         if (m != NULL) {
 965           to_process.push(m);
 966         }
 967       }
 968     }
 969   }
 970 }
 971 
 972 #ifndef PRODUCT
 973 void PhaseIterGVN::verify_step(Node* n) {
 974   if (VerifyIterativeGVN) {
 975     _verify_window[_verify_counter % _verify_window_size] = n;
 976     ++_verify_counter;
 977     ResourceMark rm;
 978     ResourceArea* area = Thread::current()->resource_area();
 979     VectorSet old_space(area), new_space(area);
 980     if (C->unique() < 1000 ||
 981         0 == _verify_counter % (C->unique() < 10000 ? 10 : 100)) {
 982       ++_verify_full_passes;
 983       Node::verify_recur(C->root(), -1, old_space, new_space);
 984     }
 985     const int verify_depth = 4;
 986     for ( int i = 0; i < _verify_window_size; i++ ) {
 987       Node* n = _verify_window[i];
 988       if ( n == NULL )  continue;
 989       if( n->in(0) == NodeSentinel ) {  // xform_idom
 990         _verify_window[i] = n->in(1);
 991         --i; continue;
 992       }
 993       // Typical fanout is 1-2, so this call visits about 6 nodes.
 994       Node::verify_recur(n, verify_depth, old_space, new_space);
 995     }
 996   }
 997 }
 998 
 999 void PhaseIterGVN::trace_PhaseIterGVN(Node* n, Node* nn, const Type* oldtype) {
1000   if (TraceIterativeGVN) {
1001     uint wlsize = _worklist.size();
1002     const Type* newtype = type_or_null(n);
1003     if (nn != n) {
1004       // print old node
1005       tty->print("< ");
1006       if (oldtype != newtype && oldtype != NULL) {
1007         oldtype->dump();
1008       }
1009       do { tty->print("\t"); } while (tty->position() < 16);
1010       tty->print("<");
1011       n->dump();
1012     }
1013     if (oldtype != newtype || nn != n) {
1014       // print new node and/or new type
1015       if (oldtype == NULL) {
1016         tty->print("* ");
1017       } else if (nn != n) {
1018         tty->print("> ");
1019       } else {
1020         tty->print("= ");
1021       }
1022       if (newtype == NULL) {
1023         tty->print("null");
1024       } else {
1025         newtype->dump();
1026       }
1027       do { tty->print("\t"); } while (tty->position() < 16);
1028       nn->dump();
1029     }
1030     if (Verbose && wlsize < _worklist.size()) {
1031       tty->print("  Push {");
1032       while (wlsize != _worklist.size()) {
1033         Node* pushed = _worklist.at(wlsize++);
1034         tty->print(" %d", pushed->_idx);
1035       }
1036       tty->print_cr(" }");
1037     }
1038     if (nn != n) {
1039       // ignore n, it might be subsumed
1040       verify_step((Node*) NULL);
1041     }
1042   }
1043 }
1044 
1045 void PhaseIterGVN::init_verifyPhaseIterGVN() {
1046   _verify_counter = 0;
1047   _verify_full_passes = 0;
1048   for (int i = 0; i < _verify_window_size; i++) {
1049     _verify_window[i] = NULL;
1050   }
1051 #ifdef ASSERT
1052   // Verify that all modified nodes are on _worklist
1053   Unique_Node_List* modified_list = C->modified_nodes();
1054   while (modified_list != NULL && modified_list->size()) {
1055     Node* n = modified_list->pop();
1056     if (n->outcnt() != 0 && !n->is_Con() && !_worklist.member(n)) {
1057       n->dump();
1058       assert(false, "modified node is not on IGVN._worklist");
1059     }
1060   }
1061 #endif
1062 }
1063 
1064 void PhaseIterGVN::verify_PhaseIterGVN() {
1065 #ifdef ASSERT
1066   // Verify nodes with changed inputs.
1067   Unique_Node_List* modified_list = C->modified_nodes();
1068   while (modified_list != NULL && modified_list->size()) {
1069     Node* n = modified_list->pop();
1070     if (n->outcnt() != 0 && !n->is_Con()) { // skip dead and Con nodes
1071       n->dump();
1072       assert(false, "modified node was not processed by IGVN.transform_old()");
1073     }
1074   }
1075 #endif
1076 
1077   C->verify_graph_edges();
1078   if( VerifyOpto && allow_progress() ) {
1079     // Must turn off allow_progress to enable assert and break recursion
1080     C->root()->verify();
1081     { // Check if any progress was missed using IterGVN
1082       // Def-Use info enables transformations not attempted in wash-pass
1083       // e.g. Region/Phi cleanup, ...
1084       // Null-check elision -- may not have reached fixpoint
1085       //                       do not propagate to dominated nodes
1086       ResourceMark rm;
1087       PhaseIterGVN igvn2(this,"Verify"); // Fresh and clean!
1088       // Fill worklist completely
1089       igvn2.init_worklist(C->root());
1090 
1091       igvn2.set_allow_progress(false);
1092       igvn2.optimize();
1093       igvn2.set_allow_progress(true);
1094     }
1095   }
1096   if (VerifyIterativeGVN && PrintOpto) {
1097     if (_verify_counter == _verify_full_passes) {
1098       tty->print_cr("VerifyIterativeGVN: %d transforms and verify passes",
1099                     (int) _verify_full_passes);
1100     } else {
1101       tty->print_cr("VerifyIterativeGVN: %d transforms, %d full verify passes",
1102                   (int) _verify_counter, (int) _verify_full_passes);
1103     }
1104   }
1105 
1106 #ifdef ASSERT
1107   while (modified_list->size()) {
1108     Node* n = modified_list->pop();
1109     n->dump();
1110     assert(false, "VerifyIterativeGVN: new modified node was added");
1111   }
1112 #endif
1113 }
1114 #endif /* PRODUCT */
1115 
1116 #ifdef ASSERT
1117 /**
1118  * Dumps information that can help to debug the problem. A debug
1119  * build fails with an assert.
1120  */
1121 void PhaseIterGVN::dump_infinite_loop_info(Node* n) {
1122   n->dump(4);
1123   _worklist.dump();
1124   assert(false, "infinite loop in PhaseIterGVN::optimize");
1125 }
1126 
1127 /**
1128  * Prints out information about IGVN if the 'verbose' option is used.
1129  */
1130 void PhaseIterGVN::trace_PhaseIterGVN_verbose(Node* n, int num_processed) {
1131   if (TraceIterativeGVN && Verbose) {
1132     tty->print("  Pop ");
1133     n->dump();
1134     if ((num_processed % 100) == 0) {
1135       _worklist.print_set();
1136     }
1137   }
1138 }
1139 #endif /* ASSERT */
1140 
1141 void PhaseIterGVN::optimize() {
1142   DEBUG_ONLY(uint num_processed  = 0;)
1143   NOT_PRODUCT(init_verifyPhaseIterGVN();)
1144 
1145   uint loop_count = 0;
1146   // Pull from worklist and transform the node. If the node has changed,
1147   // update edge info and put uses on worklist.
1148   while(_worklist.size()) {
1149     if (C->check_node_count(NodeLimitFudgeFactor * 2, "Out of nodes")) {
1150       return;
1151     }
1152     Node* n  = _worklist.pop();
1153     if (++loop_count >= K * C->live_nodes()) {
1154       DEBUG_ONLY(dump_infinite_loop_info(n);)
1155       C->record_method_not_compilable("infinite loop in PhaseIterGVN::optimize");
1156       return;
1157     }
1158     DEBUG_ONLY(trace_PhaseIterGVN_verbose(n, num_processed++);)
1159     if (n->outcnt() != 0) {
1160       NOT_PRODUCT(const Type* oldtype = type_or_null(n));
1161       // Do the transformation
1162       Node* nn = transform_old(n);
1163       NOT_PRODUCT(trace_PhaseIterGVN(n, nn, oldtype);)
1164     } else if (!n->is_top()) {
1165       remove_dead_node(n);
1166     }
1167   }
1168   NOT_PRODUCT(verify_PhaseIterGVN();)
1169 }
1170 
1171 
1172 /**
1173  * Register a new node with the optimizer.  Update the types array, the def-use
1174  * info.  Put on worklist.
1175  */
1176 Node* PhaseIterGVN::register_new_node_with_optimizer(Node* n, Node* orig) {
1177   set_type_bottom(n);
1178   _worklist.push(n);
1179   if (orig != NULL)  C->copy_node_notes_to(n, orig);
1180   return n;
1181 }
1182 
1183 //------------------------------transform--------------------------------------
1184 // Non-recursive: idealize Node 'n' with respect to its inputs and its value
1185 Node *PhaseIterGVN::transform( Node *n ) {
1186   if (_delay_transform) {
1187     // Register the node but don't optimize for now
1188     register_new_node_with_optimizer(n);
1189     return n;
1190   }
1191 
1192   // If brand new node, make space in type array, and give it a type.
1193   ensure_type_or_null(n);
1194   if (type_or_null(n) == NULL) {
1195     set_type_bottom(n);
1196   }
1197 
1198   return transform_old(n);
1199 }
1200 
1201 Node *PhaseIterGVN::transform_old(Node* n) {
1202   DEBUG_ONLY(uint loop_count = 0;);
1203   NOT_PRODUCT(set_transforms());
1204 
1205   // Remove 'n' from hash table in case it gets modified
1206   _table.hash_delete(n);
1207   if (VerifyIterativeGVN) {
1208    assert(!_table.find_index(n->_idx), "found duplicate entry in table");
1209   }
1210 
1211   // Apply the Ideal call in a loop until it no longer applies
1212   Node* k = n;
1213   DEBUG_ONLY(dead_loop_check(k);)
1214   DEBUG_ONLY(bool is_new = (k->outcnt() == 0);)
1215   C->remove_modified_node(k);
1216   Node* i = k->Ideal(this, /*can_reshape=*/true);
1217   assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes");
1218 #ifndef PRODUCT
1219   verify_step(k);
1220   if (i && VerifyOpto ) {
1221     if (!allow_progress()) {
1222       if (i->is_Add() && (i->outcnt() == 1)) {
1223         // Switched input to left side because this is the only use
1224       } else if (i->is_If() && (i->in(0) == NULL)) {
1225         // This IF is dead because it is dominated by an equivalent IF When
1226         // dominating if changed, info is not propagated sparsely to 'this'
1227         // Propagating this info further will spuriously identify other
1228         // progress.
1229         return i;
1230       } else
1231         set_progress();
1232     } else {
1233       set_progress();
1234     }
1235   }
1236 #endif
1237 
1238   while (i != NULL) {
1239 #ifdef ASSERT
1240     if (loop_count >= K) {
1241       dump_infinite_loop_info(i);
1242     }
1243     loop_count++;
1244 #endif
1245     assert((i->_idx >= k->_idx) || i->is_top(), "Idealize should return new nodes, use Identity to return old nodes");
1246     // Made a change; put users of original Node on worklist
1247     add_users_to_worklist(k);
1248     // Replacing root of transform tree?
1249     if (k != i) {
1250       // Make users of old Node now use new.
1251       subsume_node(k, i);
1252       k = i;
1253     }
1254     DEBUG_ONLY(dead_loop_check(k);)
1255     // Try idealizing again
1256     DEBUG_ONLY(is_new = (k->outcnt() == 0);)
1257     C->remove_modified_node(k);
1258     i = k->Ideal(this, /*can_reshape=*/true);
1259     assert(i != k || is_new || (i->outcnt() > 0), "don't return dead nodes");
1260 #ifndef PRODUCT
1261     verify_step(k);
1262     if (i && VerifyOpto) {
1263       set_progress();
1264     }
1265 #endif
1266   }
1267 
1268   // If brand new node, make space in type array.
1269   ensure_type_or_null(k);
1270 
1271   // See what kind of values 'k' takes on at runtime
1272   const Type* t = k->Value(this);
1273   assert(t != NULL, "value sanity");
1274 
1275   // Since I just called 'Value' to compute the set of run-time values
1276   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
1277   // cache Value.  Later requests for the local phase->type of this Node can
1278   // use the cached Value instead of suffering with 'bottom_type'.
1279   if (type_or_null(k) != t) {
1280 #ifndef PRODUCT
1281     inc_new_values();
1282     set_progress();
1283 #endif
1284     set_type(k, t);
1285     // If k is a TypeNode, capture any more-precise type permanently into Node
1286     k->raise_bottom_type(t);
1287     // Move users of node to worklist
1288     add_users_to_worklist(k);
1289   }
1290   // If 'k' computes a constant, replace it with a constant
1291   if (t->singleton() && !k->is_Con()) {
1292     NOT_PRODUCT(set_progress();)
1293     Node* con = makecon(t);     // Make a constant
1294     add_users_to_worklist(k);
1295     subsume_node(k, con);       // Everybody using k now uses con
1296     return con;
1297   }
1298 
1299   // Now check for Identities
1300   i = k->Identity(this);      // Look for a nearby replacement
1301   if (i != k) {                // Found? Return replacement!
1302     NOT_PRODUCT(set_progress();)
1303     add_users_to_worklist(k);
1304     subsume_node(k, i);       // Everybody using k now uses i
1305     return i;
1306   }
1307 
1308   // Global Value Numbering
1309   i = hash_find_insert(k);      // Check for pre-existing node
1310   if (i && (i != k)) {
1311     // Return the pre-existing node if it isn't dead
1312     NOT_PRODUCT(set_progress();)
1313     add_users_to_worklist(k);
1314     subsume_node(k, i);       // Everybody using k now uses i
1315     return i;
1316   }
1317 
1318   // Return Idealized original
1319   return k;
1320 }
1321 
1322 //---------------------------------saturate------------------------------------
1323 const Type* PhaseIterGVN::saturate(const Type* new_type, const Type* old_type,
1324                                    const Type* limit_type) const {
1325   return new_type->narrow(old_type);
1326 }
1327 
1328 //------------------------------remove_globally_dead_node----------------------
1329 // Kill a globally dead Node.  All uses are also globally dead and are
1330 // aggressively trimmed.
1331 void PhaseIterGVN::remove_globally_dead_node( Node *dead ) {
1332   enum DeleteProgress {
1333     PROCESS_INPUTS,
1334     PROCESS_OUTPUTS
1335   };
1336   assert(_stack.is_empty(), "not empty");
1337   _stack.push(dead, PROCESS_INPUTS);
1338 
1339   while (_stack.is_nonempty()) {
1340     dead = _stack.node();
1341     uint progress_state = _stack.index();
1342     assert(dead != C->root(), "killing root, eh?");
1343     assert(!dead->is_top(), "add check for top when pushing");
1344     NOT_PRODUCT( set_progress(); )
1345     if (progress_state == PROCESS_INPUTS) {
1346       // After following inputs, continue to outputs
1347       _stack.set_index(PROCESS_OUTPUTS);
1348       if (!dead->is_Con()) { // Don't kill cons but uses
1349         bool recurse = false;
1350         // Remove from hash table
1351         _table.hash_delete( dead );
1352         // Smash all inputs to 'dead', isolating him completely
1353         for (uint i = 0; i < dead->req(); i++) {
1354           Node *in = dead->in(i);
1355           if (in != NULL && in != C->top()) {  // Points to something?
1356             int nrep = dead->replace_edge(in, NULL);  // Kill edges
1357             assert((nrep > 0), "sanity");
1358             if (in->outcnt() == 0) { // Made input go dead?
1359               _stack.push(in, PROCESS_INPUTS); // Recursively remove
1360               recurse = true;
1361             } else if (in->outcnt() == 1 &&
1362                        in->has_special_unique_user()) {
1363               _worklist.push(in->unique_out());
1364             } else if (in->outcnt() <= 2 && dead->is_Phi()) {
1365               if (in->Opcode() == Op_Region) {
1366                 _worklist.push(in);
1367               } else if (in->is_Store()) {
1368                 DUIterator_Fast imax, i = in->fast_outs(imax);
1369                 _worklist.push(in->fast_out(i));
1370                 i++;
1371                 if (in->outcnt() == 2) {
1372                   _worklist.push(in->fast_out(i));
1373                   i++;
1374                 }
1375                 assert(!(i < imax), "sanity");
1376               }
1377             } else {
1378               BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(this, in);
1379             }
1380             if (ReduceFieldZeroing && dead->is_Load() && i == MemNode::Memory &&
1381                 in->is_Proj() && in->in(0) != NULL && in->in(0)->is_Initialize()) {
1382               // A Load that directly follows an InitializeNode is
1383               // going away. The Stores that follow are candidates
1384               // again to be captured by the InitializeNode.
1385               for (DUIterator_Fast jmax, j = in->fast_outs(jmax); j < jmax; j++) {
1386                 Node *n = in->fast_out(j);
1387                 if (n->is_Store()) {
1388                   _worklist.push(n);
1389                 }
1390               }
1391             }
1392           } // if (in != NULL && in != C->top())
1393         } // for (uint i = 0; i < dead->req(); i++)
1394         if (recurse) {
1395           continue;
1396         }
1397       } // if (!dead->is_Con())
1398     } // if (progress_state == PROCESS_INPUTS)
1399 
1400     // Aggressively kill globally dead uses
1401     // (Rather than pushing all the outs at once, we push one at a time,
1402     // plus the parent to resume later, because of the indefinite number
1403     // of edge deletions per loop trip.)
1404     if (dead->outcnt() > 0) {
1405       // Recursively remove output edges
1406       _stack.push(dead->raw_out(0), PROCESS_INPUTS);
1407     } else {
1408       // Finished disconnecting all input and output edges.
1409       _stack.pop();
1410       // Remove dead node from iterative worklist
1411       _worklist.remove(dead);
1412       C->remove_modified_node(dead);
1413       // Constant node that has no out-edges and has only one in-edge from
1414       // root is usually dead. However, sometimes reshaping walk makes
1415       // it reachable by adding use edges. So, we will NOT count Con nodes
1416       // as dead to be conservative about the dead node count at any
1417       // given time.
1418       if (!dead->is_Con()) {
1419         C->record_dead_node(dead->_idx);
1420       }
1421       if (dead->is_macro()) {
1422         C->remove_macro_node(dead);
1423       }
1424       if (dead->is_expensive()) {
1425         C->remove_expensive_node(dead);
1426       }
1427       CastIINode* cast = dead->isa_CastII();
1428       if (cast != NULL && cast->has_range_check()) {
1429         C->remove_range_check_cast(cast);
1430       }
1431       if (dead->Opcode() == Op_Opaque4) {
1432         C->remove_opaque4_node(dead);
1433       }
1434       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1435       bs->unregister_potential_barrier_node(dead);
1436     }
1437   } // while (_stack.is_nonempty())
1438 }
1439 
1440 //------------------------------subsume_node-----------------------------------
1441 // Remove users from node 'old' and add them to node 'nn'.
1442 void PhaseIterGVN::subsume_node( Node *old, Node *nn ) {
1443   assert( old != hash_find(old), "should already been removed" );
1444   assert( old != C->top(), "cannot subsume top node");
1445   // Copy debug or profile information to the new version:
1446   C->copy_node_notes_to(nn, old);
1447   // Move users of node 'old' to node 'nn'
1448   for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) {
1449     Node* use = old->last_out(i);  // for each use...
1450     // use might need re-hashing (but it won't if it's a new node)
1451     rehash_node_delayed(use);
1452     // Update use-def info as well
1453     // We remove all occurrences of old within use->in,
1454     // so as to avoid rehashing any node more than once.
1455     // The hash table probe swamps any outer loop overhead.
1456     uint num_edges = 0;
1457     for (uint jmax = use->len(), j = 0; j < jmax; j++) {
1458       if (use->in(j) == old) {
1459         use->set_req(j, nn);
1460         ++num_edges;
1461       }
1462     }
1463     i -= num_edges;    // we deleted 1 or more copies of this edge
1464   }
1465 
1466   // Search for instance field data PhiNodes in the same region pointing to the old
1467   // memory PhiNode and update their instance memory ids to point to the new node.
1468   if (old->is_Phi() && old->as_Phi()->type()->has_memory() && old->in(0) != NULL) {
1469     Node* region = old->in(0);
1470     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1471       PhiNode* phi = region->fast_out(i)->isa_Phi();
1472       if (phi != NULL && phi->inst_mem_id() == (int)old->_idx) {
1473         phi->set_inst_mem_id((int)nn->_idx);
1474       }
1475     }
1476   }
1477 
1478   // Smash all inputs to 'old', isolating him completely
1479   Node *temp = new Node(1);
1480   temp->init_req(0,nn);     // Add a use to nn to prevent him from dying
1481   remove_dead_node( old );
1482   temp->del_req(0);         // Yank bogus edge
1483 #ifndef PRODUCT
1484   if( VerifyIterativeGVN ) {
1485     for ( int i = 0; i < _verify_window_size; i++ ) {
1486       if ( _verify_window[i] == old )
1487         _verify_window[i] = nn;
1488     }
1489   }
1490 #endif
1491   _worklist.remove(temp);   // this can be necessary
1492   temp->destruct();         // reuse the _idx of this little guy
1493 }
1494 
1495 //------------------------------add_users_to_worklist--------------------------
1496 void PhaseIterGVN::add_users_to_worklist0( Node *n ) {
1497   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1498     _worklist.push(n->fast_out(i));  // Push on worklist
1499   }
1500 }
1501 
1502 // Return counted loop Phi if as a counted loop exit condition, cmp
1503 // compares the the induction variable with n
1504 static PhiNode* countedloop_phi_from_cmp(CmpINode* cmp, Node* n) {
1505   for (DUIterator_Fast imax, i = cmp->fast_outs(imax); i < imax; i++) {
1506     Node* bol = cmp->fast_out(i);
1507     for (DUIterator_Fast i2max, i2 = bol->fast_outs(i2max); i2 < i2max; i2++) {
1508       Node* iff = bol->fast_out(i2);
1509       if (iff->is_CountedLoopEnd()) {
1510         CountedLoopEndNode* cle = iff->as_CountedLoopEnd();
1511         if (cle->limit() == n) {
1512           PhiNode* phi = cle->phi();
1513           if (phi != NULL) {
1514             return phi;
1515           }
1516         }
1517       }
1518     }
1519   }
1520   return NULL;
1521 }
1522 
1523 void PhaseIterGVN::add_users_to_worklist( Node *n ) {
1524   add_users_to_worklist0(n);
1525 
1526   // Move users of node to worklist
1527   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1528     Node* use = n->fast_out(i); // Get use
1529 
1530     if( use->is_Multi() ||      // Multi-definer?  Push projs on worklist
1531         use->is_Store() )       // Enable store/load same address
1532       add_users_to_worklist0(use);
1533 
1534     // If we changed the receiver type to a call, we need to revisit
1535     // the Catch following the call.  It's looking for a non-NULL
1536     // receiver to know when to enable the regular fall-through path
1537     // in addition to the NullPtrException path.
1538     if (use->is_CallDynamicJava() && n == use->in(TypeFunc::Parms)) {
1539       Node* p = use->as_CallDynamicJava()->proj_out_or_null(TypeFunc::Control);
1540       if (p != NULL) {
1541         add_users_to_worklist0(p);
1542       }
1543     }
1544 
1545     uint use_op = use->Opcode();
1546     if(use->is_Cmp()) {       // Enable CMP/BOOL optimization
1547       add_users_to_worklist(use); // Put Bool on worklist
1548       if (use->outcnt() > 0) {
1549         Node* bol = use->raw_out(0);
1550         if (bol->outcnt() > 0) {
1551           Node* iff = bol->raw_out(0);
1552           if (iff->outcnt() == 2) {
1553             // Look for the 'is_x2logic' pattern: "x ? : 0 : 1" and put the
1554             // phi merging either 0 or 1 onto the worklist
1555             Node* ifproj0 = iff->raw_out(0);
1556             Node* ifproj1 = iff->raw_out(1);
1557             if (ifproj0->outcnt() > 0 && ifproj1->outcnt() > 0) {
1558               Node* region0 = ifproj0->raw_out(0);
1559               Node* region1 = ifproj1->raw_out(0);
1560               if( region0 == region1 )
1561                 add_users_to_worklist0(region0);
1562             }
1563           }
1564         }
1565       }
1566       if (use_op == Op_CmpI) {
1567         Node* phi = countedloop_phi_from_cmp((CmpINode*)use, n);
1568         if (phi != NULL) {
1569           // If an opaque node feeds into the limit condition of a
1570           // CountedLoop, we need to process the Phi node for the
1571           // induction variable when the opaque node is removed:
1572           // the range of values taken by the Phi is now known and
1573           // so its type is also known.
1574           _worklist.push(phi);
1575         }
1576         Node* in1 = use->in(1);
1577         for (uint i = 0; i < in1->outcnt(); i++) {
1578           if (in1->raw_out(i)->Opcode() == Op_CastII) {
1579             Node* castii = in1->raw_out(i);
1580             if (castii->in(0) != NULL && castii->in(0)->in(0) != NULL && castii->in(0)->in(0)->is_If()) {
1581               Node* ifnode = castii->in(0)->in(0);
1582               if (ifnode->in(1) != NULL && ifnode->in(1)->is_Bool() && ifnode->in(1)->in(1) == use) {
1583                 // Reprocess a CastII node that may depend on an
1584                 // opaque node value when the opaque node is
1585                 // removed. In case it carries a dependency we can do
1586                 // a better job of computing its type.
1587                 _worklist.push(castii);
1588               }
1589             }
1590           }
1591         }
1592       }
1593     }
1594 
1595     // If changed Cast input, check Phi users for simple cycles
1596     if (use->is_ConstraintCast()) {
1597       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1598         Node* u = use->fast_out(i2);
1599         if (u->is_Phi())
1600           _worklist.push(u);
1601       }
1602     }
1603     // If changed LShift inputs, check RShift users for useless sign-ext
1604     if( use_op == Op_LShiftI ) {
1605       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1606         Node* u = use->fast_out(i2);
1607         if (u->Opcode() == Op_RShiftI)
1608           _worklist.push(u);
1609       }
1610     }
1611     // If changed AddI/SubI inputs, check CmpU for range check optimization.
1612     if (use_op == Op_AddI || use_op == Op_SubI) {
1613       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1614         Node* u = use->fast_out(i2);
1615         if (u->is_Cmp() && (u->Opcode() == Op_CmpU)) {
1616           _worklist.push(u);
1617         }
1618       }
1619     }
1620     // If changed AddP inputs, check Stores for loop invariant
1621     if( use_op == Op_AddP ) {
1622       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1623         Node* u = use->fast_out(i2);
1624         if (u->is_Mem())
1625           _worklist.push(u);
1626       }
1627     }
1628     // If changed initialization activity, check dependent Stores
1629     if (use_op == Op_Allocate || use_op == Op_AllocateArray) {
1630       InitializeNode* init = use->as_Allocate()->initialization();
1631       if (init != NULL) {
1632         Node* imem = init->proj_out_or_null(TypeFunc::Memory);
1633         if (imem != NULL)  add_users_to_worklist0(imem);
1634       }
1635     }
1636     if (use_op == Op_Initialize) {
1637       Node* imem = use->as_Initialize()->proj_out_or_null(TypeFunc::Memory);
1638       if (imem != NULL)  add_users_to_worklist0(imem);
1639     }
1640     // Loading the java mirror from a Klass requires two loads and the type
1641     // of the mirror load depends on the type of 'n'. See LoadNode::Value().
1642     //   LoadBarrier?(LoadP(LoadP(AddP(foo:Klass, #java_mirror))))
1643     BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1644     bool has_load_barriers = bs->has_load_barriers();
1645 
1646     if (use_op == Op_LoadP && use->bottom_type()->isa_rawptr()) {
1647       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1648         Node* u = use->fast_out(i2);
1649         const Type* ut = u->bottom_type();
1650         if (u->Opcode() == Op_LoadP && ut->isa_instptr()) {
1651           if (has_load_barriers) {
1652             // Search for load barriers behind the load
1653             for (DUIterator_Fast i3max, i3 = u->fast_outs(i3max); i3 < i3max; i3++) {
1654               Node* b = u->fast_out(i3);
1655               if (bs->is_gc_barrier_node(b)) {
1656                 _worklist.push(b);
1657               }
1658             }
1659           }
1660           _worklist.push(u);
1661         }
1662       }
1663     }
1664   }
1665 }
1666 
1667 /**
1668  * Remove the speculative part of all types that we know of
1669  */
1670 void PhaseIterGVN::remove_speculative_types()  {
1671   assert(UseTypeSpeculation, "speculation is off");
1672   for (uint i = 0; i < _types.Size(); i++)  {
1673     const Type* t = _types.fast_lookup(i);
1674     if (t != NULL) {
1675       _types.map(i, t->remove_speculative());
1676     }
1677   }
1678   _table.check_no_speculative_types();
1679 }
1680 
1681 //=============================================================================
1682 #ifndef PRODUCT
1683 uint PhaseCCP::_total_invokes   = 0;
1684 uint PhaseCCP::_total_constants = 0;
1685 #endif
1686 //------------------------------PhaseCCP---------------------------------------
1687 // Conditional Constant Propagation, ala Wegman & Zadeck
1688 PhaseCCP::PhaseCCP( PhaseIterGVN *igvn ) : PhaseIterGVN(igvn) {
1689   NOT_PRODUCT( clear_constants(); )
1690   assert( _worklist.size() == 0, "" );
1691   // Clear out _nodes from IterGVN.  Must be clear to transform call.
1692   _nodes.clear();               // Clear out from IterGVN
1693   analyze();
1694 }
1695 
1696 #ifndef PRODUCT
1697 //------------------------------~PhaseCCP--------------------------------------
1698 PhaseCCP::~PhaseCCP() {
1699   inc_invokes();
1700   _total_constants += count_constants();
1701 }
1702 #endif
1703 
1704 
1705 #ifdef ASSERT
1706 static bool ccp_type_widens(const Type* t, const Type* t0) {
1707   assert(t->meet(t0) == t, "Not monotonic");
1708   switch (t->base() == t0->base() ? t->base() : Type::Top) {
1709   case Type::Int:
1710     assert(t0->isa_int()->_widen <= t->isa_int()->_widen, "widen increases");
1711     break;
1712   case Type::Long:
1713     assert(t0->isa_long()->_widen <= t->isa_long()->_widen, "widen increases");
1714     break;
1715   default:
1716     break;
1717   }
1718   return true;
1719 }
1720 #endif //ASSERT
1721 
1722 //------------------------------analyze----------------------------------------
1723 void PhaseCCP::analyze() {
1724   // Initialize all types to TOP, optimistic analysis
1725   for (int i = C->unique() - 1; i >= 0; i--)  {
1726     _types.map(i,Type::TOP);
1727   }
1728 
1729   // Push root onto worklist
1730   Unique_Node_List worklist;
1731   worklist.push(C->root());
1732 
1733   // Pull from worklist; compute new value; push changes out.
1734   // This loop is the meat of CCP.
1735   while( worklist.size() ) {
1736     Node *n = worklist.pop();
1737     const Type *t = n->Value(this);
1738     if (t != type(n)) {
1739       assert(ccp_type_widens(t, type(n)), "ccp type must widen");
1740 #ifndef PRODUCT
1741       if( TracePhaseCCP ) {
1742         t->dump();
1743         do { tty->print("\t"); } while (tty->position() < 16);
1744         n->dump();
1745       }
1746 #endif
1747       set_type(n, t);
1748       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1749         Node* m = n->fast_out(i);   // Get user
1750         if (m->is_Region()) {  // New path to Region?  Must recheck Phis too
1751           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1752             Node* p = m->fast_out(i2); // Propagate changes to uses
1753             if (p->bottom_type() != type(p)) { // If not already bottomed out
1754               worklist.push(p); // Propagate change to user
1755             }
1756           }
1757         }
1758         // If we changed the receiver type to a call, we need to revisit
1759         // the Catch following the call.  It's looking for a non-NULL
1760         // receiver to know when to enable the regular fall-through path
1761         // in addition to the NullPtrException path
1762         if (m->is_Call()) {
1763           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1764             Node* p = m->fast_out(i2);  // Propagate changes to uses
1765             if (p->is_Proj() && p->as_Proj()->_con == TypeFunc::Control && p->outcnt() == 1) {
1766               worklist.push(p->unique_out());
1767             }
1768           }
1769         }
1770         if (m->bottom_type() != type(m)) { // If not already bottomed out
1771           worklist.push(m);     // Propagate change to user
1772         }
1773 
1774         // CmpU nodes can get their type information from two nodes up in the
1775         // graph (instead of from the nodes immediately above). Make sure they
1776         // are added to the worklist if nodes they depend on are updated, since
1777         // they could be missed and get wrong types otherwise.
1778         uint m_op = m->Opcode();
1779         if (m_op == Op_AddI || m_op == Op_SubI) {
1780           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1781             Node* p = m->fast_out(i2); // Propagate changes to uses
1782             if (p->Opcode() == Op_CmpU) {
1783               // Got a CmpU which might need the new type information from node n.
1784               if(p->bottom_type() != type(p)) { // If not already bottomed out
1785                 worklist.push(p); // Propagate change to user
1786               }
1787             }
1788           }
1789         }
1790         // If n is used in a counted loop exit condition then the type
1791         // of the counted loop's Phi depends on the type of n. See
1792         // PhiNode::Value().
1793         if (m_op == Op_CmpI) {
1794           PhiNode* phi = countedloop_phi_from_cmp((CmpINode*)m, n);
1795           if (phi != NULL) {
1796             worklist.push(phi);
1797           }
1798         }
1799         // Loading the java mirror from a Klass requires two loads and the type
1800         // of the mirror load depends on the type of 'n'. See LoadNode::Value().
1801         BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1802         bool has_load_barriers = bs->has_load_barriers();
1803 
1804         if (m_op == Op_LoadP && m->bottom_type()->isa_rawptr()) {
1805           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
1806             Node* u = m->fast_out(i2);
1807             const Type* ut = u->bottom_type();
1808             if (u->Opcode() == Op_LoadP && ut->isa_instptr() && ut != type(u)) {
1809               if (has_load_barriers) {
1810                 // Search for load barriers behind the load
1811                 for (DUIterator_Fast i3max, i3 = u->fast_outs(i3max); i3 < i3max; i3++) {
1812                   Node* b = u->fast_out(i3);
1813                   if (bs->is_gc_barrier_node(b)) {
1814                     _worklist.push(b);
1815                   }
1816                 }
1817               }
1818               worklist.push(u);
1819             }
1820           }
1821         }
1822       }
1823     }
1824   }
1825 }
1826 
1827 //------------------------------do_transform-----------------------------------
1828 // Top level driver for the recursive transformer
1829 void PhaseCCP::do_transform() {
1830   // Correct leaves of new-space Nodes; they point to old-space.
1831   C->set_root( transform(C->root())->as_Root() );
1832   assert( C->top(),  "missing TOP node" );
1833   assert( C->root(), "missing root" );
1834 }
1835 
1836 //------------------------------transform--------------------------------------
1837 // Given a Node in old-space, clone him into new-space.
1838 // Convert any of his old-space children into new-space children.
1839 Node *PhaseCCP::transform( Node *n ) {
1840   Node *new_node = _nodes[n->_idx]; // Check for transformed node
1841   if( new_node != NULL )
1842     return new_node;                // Been there, done that, return old answer
1843   new_node = transform_once(n);     // Check for constant
1844   _nodes.map( n->_idx, new_node );  // Flag as having been cloned
1845 
1846   // Allocate stack of size _nodes.Size()/2 to avoid frequent realloc
1847   GrowableArray <Node *> trstack(C->live_nodes() >> 1);
1848 
1849   trstack.push(new_node);           // Process children of cloned node
1850   while ( trstack.is_nonempty() ) {
1851     Node *clone = trstack.pop();
1852     uint cnt = clone->req();
1853     for( uint i = 0; i < cnt; i++ ) {          // For all inputs do
1854       Node *input = clone->in(i);
1855       if( input != NULL ) {                    // Ignore NULLs
1856         Node *new_input = _nodes[input->_idx]; // Check for cloned input node
1857         if( new_input == NULL ) {
1858           new_input = transform_once(input);   // Check for constant
1859           _nodes.map( input->_idx, new_input );// Flag as having been cloned
1860           trstack.push(new_input);
1861         }
1862         assert( new_input == clone->in(i), "insanity check");
1863       }
1864     }
1865   }
1866   return new_node;
1867 }
1868 
1869 
1870 //------------------------------transform_once---------------------------------
1871 // For PhaseCCP, transformation is IDENTITY unless Node computed a constant.
1872 Node *PhaseCCP::transform_once( Node *n ) {
1873   const Type *t = type(n);
1874   // Constant?  Use constant Node instead
1875   if( t->singleton() ) {
1876     Node *nn = n;               // Default is to return the original constant
1877     if( t == Type::TOP ) {
1878       // cache my top node on the Compile instance
1879       if( C->cached_top_node() == NULL || C->cached_top_node()->in(0) == NULL ) {
1880         C->set_cached_top_node(ConNode::make(Type::TOP));
1881         set_type(C->top(), Type::TOP);
1882       }
1883       nn = C->top();
1884     }
1885     if( !n->is_Con() ) {
1886       if( t != Type::TOP ) {
1887         nn = makecon(t);        // ConNode::make(t);
1888         NOT_PRODUCT( inc_constants(); )
1889       } else if( n->is_Region() ) { // Unreachable region
1890         // Note: nn == C->top()
1891         n->set_req(0, NULL);        // Cut selfreference
1892         bool progress = true;
1893         uint max = n->outcnt();
1894         DUIterator i;
1895         while (progress) {
1896           progress = false;
1897           // Eagerly remove dead phis to avoid phis copies creation.
1898           for (i = n->outs(); n->has_out(i); i++) {
1899             Node* m = n->out(i);
1900             if (m->is_Phi()) {
1901               assert(type(m) == Type::TOP, "Unreachable region should not have live phis.");
1902               replace_node(m, nn);
1903               if (max != n->outcnt()) {
1904                 progress = true;
1905                 i = n->refresh_out_pos(i);
1906                 max = n->outcnt();
1907               }
1908             }
1909           }
1910         }
1911       }
1912       replace_node(n,nn);       // Update DefUse edges for new constant
1913     }
1914     return nn;
1915   }
1916 
1917   // If x is a TypeNode, capture any more-precise type permanently into Node
1918   if (t != n->bottom_type()) {
1919     hash_delete(n);             // changing bottom type may force a rehash
1920     n->raise_bottom_type(t);
1921     _worklist.push(n);          // n re-enters the hash table via the worklist
1922   }
1923 
1924   // TEMPORARY fix to ensure that 2nd GVN pass eliminates NULL checks
1925   switch( n->Opcode() ) {
1926   case Op_FastLock:      // Revisit FastLocks for lock coarsening
1927   case Op_If:
1928   case Op_CountedLoopEnd:
1929   case Op_Region:
1930   case Op_Loop:
1931   case Op_CountedLoop:
1932   case Op_Conv2B:
1933   case Op_Opaque1:
1934   case Op_Opaque2:
1935     _worklist.push(n);
1936     break;
1937   default:
1938     break;
1939   }
1940 
1941   return  n;
1942 }
1943 
1944 //---------------------------------saturate------------------------------------
1945 const Type* PhaseCCP::saturate(const Type* new_type, const Type* old_type,
1946                                const Type* limit_type) const {
1947   const Type* wide_type = new_type->widen(old_type, limit_type);
1948   if (wide_type != new_type) {          // did we widen?
1949     // If so, we may have widened beyond the limit type.  Clip it back down.
1950     new_type = wide_type->filter(limit_type);
1951   }
1952   return new_type;
1953 }
1954 
1955 //------------------------------print_statistics-------------------------------
1956 #ifndef PRODUCT
1957 void PhaseCCP::print_statistics() {
1958   tty->print_cr("CCP: %d  constants found: %d", _total_invokes, _total_constants);
1959 }
1960 #endif
1961 
1962 
1963 //=============================================================================
1964 #ifndef PRODUCT
1965 uint PhasePeephole::_total_peepholes = 0;
1966 #endif
1967 //------------------------------PhasePeephole----------------------------------
1968 // Conditional Constant Propagation, ala Wegman & Zadeck
1969 PhasePeephole::PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg )
1970   : PhaseTransform(Peephole), _regalloc(regalloc), _cfg(cfg) {
1971   NOT_PRODUCT( clear_peepholes(); )
1972 }
1973 
1974 #ifndef PRODUCT
1975 //------------------------------~PhasePeephole---------------------------------
1976 PhasePeephole::~PhasePeephole() {
1977   _total_peepholes += count_peepholes();
1978 }
1979 #endif
1980 
1981 //------------------------------transform--------------------------------------
1982 Node *PhasePeephole::transform( Node *n ) {
1983   ShouldNotCallThis();
1984   return NULL;
1985 }
1986 
1987 //------------------------------do_transform-----------------------------------
1988 void PhasePeephole::do_transform() {
1989   bool method_name_not_printed = true;
1990 
1991   // Examine each basic block
1992   for (uint block_number = 1; block_number < _cfg.number_of_blocks(); ++block_number) {
1993     Block* block = _cfg.get_block(block_number);
1994     bool block_not_printed = true;
1995 
1996     // and each instruction within a block
1997     uint end_index = block->number_of_nodes();
1998     // block->end_idx() not valid after PhaseRegAlloc
1999     for( uint instruction_index = 1; instruction_index < end_index; ++instruction_index ) {
2000       Node     *n = block->get_node(instruction_index);
2001       if( n->is_Mach() ) {
2002         MachNode *m = n->as_Mach();
2003         int deleted_count = 0;
2004         // check for peephole opportunities
2005         MachNode *m2 = m->peephole(block, instruction_index, _regalloc, deleted_count);
2006         if( m2 != NULL ) {
2007 #ifndef PRODUCT
2008           if( PrintOptoPeephole ) {
2009             // Print method, first time only
2010             if( C->method() && method_name_not_printed ) {
2011               C->method()->print_short_name(); tty->cr();
2012               method_name_not_printed = false;
2013             }
2014             // Print this block
2015             if( Verbose && block_not_printed) {
2016               tty->print_cr("in block");
2017               block->dump();
2018               block_not_printed = false;
2019             }
2020             // Print instructions being deleted
2021             for( int i = (deleted_count - 1); i >= 0; --i ) {
2022               block->get_node(instruction_index-i)->as_Mach()->format(_regalloc); tty->cr();
2023             }
2024             tty->print_cr("replaced with");
2025             // Print new instruction
2026             m2->format(_regalloc);
2027             tty->print("\n\n");
2028           }
2029 #endif
2030           // Remove old nodes from basic block and update instruction_index
2031           // (old nodes still exist and may have edges pointing to them
2032           //  as register allocation info is stored in the allocator using
2033           //  the node index to live range mappings.)
2034           uint safe_instruction_index = (instruction_index - deleted_count);
2035           for( ; (instruction_index > safe_instruction_index); --instruction_index ) {
2036             block->remove_node( instruction_index );
2037           }
2038           // install new node after safe_instruction_index
2039           block->insert_node(m2, safe_instruction_index + 1);
2040           end_index = block->number_of_nodes() - 1; // Recompute new block size
2041           NOT_PRODUCT( inc_peepholes(); )
2042         }
2043       }
2044     }
2045   }
2046 }
2047 
2048 //------------------------------print_statistics-------------------------------
2049 #ifndef PRODUCT
2050 void PhasePeephole::print_statistics() {
2051   tty->print_cr("Peephole: peephole rules applied: %d",  _total_peepholes);
2052 }
2053 #endif
2054 
2055 
2056 //=============================================================================
2057 //------------------------------set_req_X--------------------------------------
2058 void Node::set_req_X( uint i, Node *n, PhaseIterGVN *igvn ) {
2059   assert( is_not_dead(n), "can not use dead node");
2060   assert( igvn->hash_find(this) != this, "Need to remove from hash before changing edges" );
2061   Node *old = in(i);
2062   set_req(i, n);
2063 
2064   // old goes dead?
2065   if( old ) {
2066     switch (old->outcnt()) {
2067     case 0:
2068       // Put into the worklist to kill later. We do not kill it now because the
2069       // recursive kill will delete the current node (this) if dead-loop exists
2070       if (!old->is_top())
2071         igvn->_worklist.push( old );
2072       break;
2073     case 1:
2074       if( old->is_Store() || old->has_special_unique_user() )
2075         igvn->add_users_to_worklist( old );
2076       break;
2077     case 2:
2078       if( old->is_Store() )
2079         igvn->add_users_to_worklist( old );
2080       if( old->Opcode() == Op_Region )
2081         igvn->_worklist.push(old);
2082       break;
2083     case 3:
2084       if( old->Opcode() == Op_Region ) {
2085         igvn->_worklist.push(old);
2086         igvn->add_users_to_worklist( old );
2087       }
2088       break;
2089     default:
2090       break;
2091     }
2092 
2093     BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, old);
2094   }
2095 
2096 }
2097 
2098 //-------------------------------replace_by-----------------------------------
2099 // Using def-use info, replace one node for another.  Follow the def-use info
2100 // to all users of the OLD node.  Then make all uses point to the NEW node.
2101 void Node::replace_by(Node *new_node) {
2102   assert(!is_top(), "top node has no DU info");
2103   for (DUIterator_Last imin, i = last_outs(imin); i >= imin; ) {
2104     Node* use = last_out(i);
2105     uint uses_found = 0;
2106     for (uint j = 0; j < use->len(); j++) {
2107       if (use->in(j) == this) {
2108         if (j < use->req())
2109               use->set_req(j, new_node);
2110         else  use->set_prec(j, new_node);
2111         uses_found++;
2112       }
2113     }
2114     i -= uses_found;    // we deleted 1 or more copies of this edge
2115   }
2116 }
2117 
2118 //=============================================================================
2119 //-----------------------------------------------------------------------------
2120 void Type_Array::grow( uint i ) {
2121   if( !_max ) {
2122     _max = 1;
2123     _types = (const Type**)_a->Amalloc( _max * sizeof(Type*) );
2124     _types[0] = NULL;
2125   }
2126   uint old = _max;
2127   while( i >= _max ) _max <<= 1;        // Double to fit
2128   _types = (const Type**)_a->Arealloc( _types, old*sizeof(Type*),_max*sizeof(Type*));
2129   memset( &_types[old], 0, (_max-old)*sizeof(Type*) );
2130 }
2131 
2132 //------------------------------dump-------------------------------------------
2133 #ifndef PRODUCT
2134 void Type_Array::dump() const {
2135   uint max = Size();
2136   for( uint i = 0; i < max; i++ ) {
2137     if( _types[i] != NULL ) {
2138       tty->print("  %d\t== ", i); _types[i]->dump(); tty->cr();
2139     }
2140   }
2141 }
2142 #endif