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