jdk8-mips64-public/hotspot: src/share/vm/opto/phaseX.cpp@98cb887364d3 (annotated)

src/share/vm/opto/phaseX.cpp@98cb887364d3 (annotated)

src/share/vm/opto/phaseX.cpp

Fri, 27 Feb 2009 13:27:09 -0800

author: twisti
date: Fri, 27 Feb 2009 13:27:09 -0800
changeset 1040: 98cb887364d3
parent 740: ab075d07f1ba
child 1362: 662f330d7275
permissions: -rw-r--r--

6810672: Comment typos
Summary: I have collected some typos I have found while looking at the code.
Reviewed-by: kvn, never

 /*
  * Copyright 1997-2008 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 #include "incls/_precompiled.incl"
 #include "incls/_phaseX.cpp.incl"
 //=============================================================================
 #define NODE_HASH_MINIMUM_SIZE    255
 //------------------------------NodeHash---------------------------------------
 NodeHash::NodeHash(uint est_max_size) :
   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
   _a(Thread::current()->resource_area()),
   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) ), // (Node**)_a->Amalloc(_max * sizeof(Node*)) ),
   _inserts(0), _insert_limit( insert_limit() ),
   _look_probes(0), _lookup_hits(0), _lookup_misses(0),
   _total_insert_probes(0), _total_inserts(0),
   _insert_probes(0), _grows(0) {
   // _sentinel must be in the current node space
   _sentinel = new (Compile::current(), 1) ProjNode(NULL, TypeFunc::Control);
   memset(_table,0,sizeof(Node*)*_max);
 }
 //------------------------------NodeHash---------------------------------------
 NodeHash::NodeHash(Arena *arena, uint est_max_size) :
   _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
   _a(arena),
   _table( NEW_ARENA_ARRAY( _a , Node* , _max ) ),
   _inserts(0), _insert_limit( insert_limit() ),
   _look_probes(0), _lookup_hits(0), _lookup_misses(0),
   _delete_probes(0), _delete_hits(0), _delete_misses(0),
   _total_insert_probes(0), _total_inserts(0),
   _insert_probes(0), _grows(0) {
   // _sentinel must be in the current node space
   _sentinel = new (Compile::current(), 1) ProjNode(NULL, TypeFunc::Control);
   memset(_table,0,sizeof(Node*)*_max);
 }
 //------------------------------NodeHash---------------------------------------
 NodeHash::NodeHash(NodeHash *nh) {
   debug_only(_table = (Node**)badAddress);   // interact correctly w/ operator=
   // just copy in all the fields
   *this = *nh;
   // nh->_sentinel must be in the current node space
 }
 //------------------------------hash_find--------------------------------------
 // Find in hash table
 Node *NodeHash::hash_find( const Node *n ) {
   // ((Node*)n)->set_hash( n->hash() );
   uint hash = n->hash();
   if (hash == Node::NO_HASH) {
     debug_only( _lookup_misses++ );
     return NULL;
   }
   uint key = hash & (_max-1);
   uint stride = key | 0x01;
   debug_only( _look_probes++ );
   Node *k = _table[key];        // Get hashed value
   if( !k ) {                    // ?Miss?
     debug_only( _lookup_misses++ );
     return NULL;                // Miss!
   }
   int op = n->Opcode();
   uint req = n->req();
   while( 1 ) {                  // While probing hash table
     if( k->req() == req &&      // Same count of inputs
         k->Opcode() == op ) {   // Same Opcode
       for( uint i=0; i<req; i++ )
         if( n->in(i)!=k->in(i)) // Different inputs?
           goto collision;       // "goto" is a speed hack...
       if( n->cmp(*k) ) {        // Check for any special bits
         debug_only( _lookup_hits++ );
         return k;               // Hit!
       }
     }
   collision:
     debug_only( _look_probes++ );
     key = (key + stride/*7*/) & (_max-1); // Stride through table with relative prime
     k = _table[key];            // Get hashed value
     if( !k ) {                  // ?Miss?
       debug_only( _lookup_misses++ );
       return NULL;              // Miss!
     }
   }
   ShouldNotReachHere();
   return NULL;
 }
 //------------------------------hash_find_insert-------------------------------
 // Find in hash table, insert if not already present
 // Used to preserve unique entries in hash table
 Node *NodeHash::hash_find_insert( Node *n ) {
   // n->set_hash( );
   uint hash = n->hash();
   if (hash == Node::NO_HASH) {
     debug_only( _lookup_misses++ );
     return NULL;
   }
   uint key = hash & (_max-1);
   uint stride = key | 0x01;     // stride must be relatively prime to table siz
   uint first_sentinel = 0;      // replace a sentinel if seen.
   debug_only( _look_probes++ );
   Node *k = _table[key];        // Get hashed value
   if( !k ) {                    // ?Miss?
     debug_only( _lookup_misses++ );
     _table[key] = n;            // Insert into table!
     debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
     check_grow();               // Grow table if insert hit limit
     return NULL;                // Miss!
   }
   else if( k == _sentinel ) {
     first_sentinel = key;      // Can insert here
   }
   int op = n->Opcode();
   uint req = n->req();
   while( 1 ) {                  // While probing hash table
     if( k->req() == req &&      // Same count of inputs
         k->Opcode() == op ) {   // Same Opcode
       for( uint i=0; i<req; i++ )
         if( n->in(i)!=k->in(i)) // Different inputs?
           goto collision;       // "goto" is a speed hack...
       if( n->cmp(*k) ) {        // Check for any special bits
         debug_only( _lookup_hits++ );
         return k;               // Hit!
       }
     }
   collision:
     debug_only( _look_probes++ );
     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
     k = _table[key];            // Get hashed value
     if( !k ) {                  // ?Miss?
       debug_only( _lookup_misses++ );
       key = (first_sentinel == 0) ? key : first_sentinel; // ?saw sentinel?
       _table[key] = n;          // Insert into table!
       debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
       check_grow();             // Grow table if insert hit limit
       return NULL;              // Miss!
     }
     else if( first_sentinel == 0 && k == _sentinel ) {
       first_sentinel = key;    // Can insert here
     }
   }
   ShouldNotReachHere();
   return NULL;
 }
 //------------------------------hash_insert------------------------------------
 // Insert into hash table
 void NodeHash::hash_insert( Node *n ) {
   // // "conflict" comments -- print nodes that conflict
   // bool conflict = false;
   // n->set_hash();
   uint hash = n->hash();
   if (hash == Node::NO_HASH) {
     return;
   }
   check_grow();
   uint key = hash & (_max-1);
   uint stride = key | 0x01;
   while( 1 ) {                  // While probing hash table
     debug_only( _insert_probes++ );
     Node *k = _table[key];      // Get hashed value
     if( !k || (k == _sentinel) ) break;       // Found a slot
     assert( k != n, "already inserted" );
     // if( PrintCompilation && PrintOptoStatistics && Verbose ) { tty->print("  conflict: "); k->dump(); conflict = true; }
     key = (key + stride) & (_max-1); // Stride through table w/ relative prime
   }
   _table[key] = n;              // Insert into table!
   debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
   // if( conflict ) { n->dump(); }
 }
 //------------------------------hash_delete------------------------------------
 // Replace in hash table with sentinel
 bool NodeHash::hash_delete( const Node *n ) {
   Node *k;
   uint hash = n->hash();
   if (hash == Node::NO_HASH) {
     debug_only( _delete_misses++ );
     return false;
   }
   uint key = hash & (_max-1);
   uint stride = key | 0x01;
   debug_only( uint counter = 0; );
   for( ; /* (k != NULL) && (k != _sentinel) */; ) {
     debug_only( counter++ );
     debug_only( _delete_probes++ );
     k = _table[key];            // Get hashed value
     if( !k ) {                  // Miss?
       debug_only( _delete_misses++ );
 #ifdef ASSERT
       if( VerifyOpto ) {
         for( uint i=0; i < _max; i++ )
           assert( _table[i] != n, "changed edges with rehashing" );
       }
 #endif
       return false;             // Miss! Not in chain
     }
     else if( n == k ) {
       debug_only( _delete_hits++ );
       _table[key] = _sentinel;  // Hit! Label as deleted entry
       debug_only(((Node*)n)->exit_hash_lock()); // Unlock the node upon removal from table.
       return true;
     }
     else {
       // collision: move through table with prime offset
       key = (key + stride/*7*/) & (_max-1);
       assert( counter <= _insert_limit, "Cycle in hash-table");
     }
   }
   ShouldNotReachHere();
   return false;
 }
 //------------------------------round_up---------------------------------------
 // Round up to nearest power of 2
 uint NodeHash::round_up( uint x ) {
   x += (x>>2);                  // Add 25% slop
   if( x <16 ) return 16;        // Small stuff
   uint i=16;
   while( i < x ) i <<= 1;       // Double to fit
   return i;                     // Return hash table size
 }
 //------------------------------grow-------------------------------------------
 // Grow _table to next power of 2 and insert old entries
 void  NodeHash::grow() {
   // Record old state
   uint   old_max   = _max;
   Node **old_table = _table;
   // Construct new table with twice the space
   _grows++;
   _total_inserts       += _inserts;
   _total_insert_probes += _insert_probes;
   _inserts         = 0;
   _insert_probes   = 0;
   _max     = _max << 1;
   _table   = NEW_ARENA_ARRAY( _a , Node* , _max ); // (Node**)_a->Amalloc( _max * sizeof(Node*) );
   memset(_table,0,sizeof(Node*)*_max);
   _insert_limit = insert_limit();
   // Insert old entries into the new table
   for( uint i = 0; i < old_max; i++ ) {
     Node *m = *old_table++;
     if( !m || m == _sentinel ) continue;
     debug_only(m->exit_hash_lock()); // Unlock the node upon removal from old table.
     hash_insert(m);
   }
 }
 //------------------------------clear------------------------------------------
 // Clear all entries in _table to NULL but keep storage
 void  NodeHash::clear() {
 #ifdef ASSERT
   // Unlock all nodes upon removal from table.
   for (uint i = 0; i < _max; i++) {
     Node* n = _table[i];
     if (!n || n == _sentinel)  continue;
     n->exit_hash_lock();
   }
 #endif
   memset( _table, 0, _max * sizeof(Node*) );
 }
 //-----------------------remove_useless_nodes----------------------------------
 // Remove useless nodes from value table,
 // implementation does not depend on hash function
 void NodeHash::remove_useless_nodes(VectorSet &useful) {
   // Dead nodes in the hash table inherited from GVN should not replace
   // existing nodes, remove dead nodes.
   uint max = size();
   Node *sentinel_node = sentinel();
   for( uint i = 0; i < max; ++i ) {
     Node *n = at(i);
     if(n != NULL && n != sentinel_node && !useful.test(n->_idx)) {
       debug_only(n->exit_hash_lock()); // Unlock the node when removed
       _table[i] = sentinel_node;       // Replace with placeholder
     }
   }
 }
 #ifndef PRODUCT
 //------------------------------dump-------------------------------------------
 // Dump statistics for the hash table
 void NodeHash::dump() {
   _total_inserts       += _inserts;
   _total_insert_probes += _insert_probes;
   if( PrintCompilation && PrintOptoStatistics && Verbose && (_inserts > 0) ) { // PrintOptoGVN
     if( PrintCompilation2 ) {
       for( uint i=0; i<_max; i++ )
       if( _table[i] )
         tty->print("%d/%d/%d ",i,_table[i]->hash()&(_max-1),_table[i]->_idx);
     }
     tty->print("\nGVN Hash stats:  %d grows to %d max_size\n", _grows, _max);
     tty->print("  %d/%d (%8.1f%% full)\n", _inserts, _max, (double)_inserts/_max*100.0);
     tty->print("  %dp/(%dh+%dm) (%8.2f probes/lookup)\n", _look_probes, _lookup_hits, _lookup_misses, (double)_look_probes/(_lookup_hits+_lookup_misses));
     tty->print("  %dp/%di (%8.2f probes/insert)\n", _total_insert_probes, _total_inserts, (double)_total_insert_probes/_total_inserts);
     // sentinels increase lookup cost, but not insert cost
     assert((_lookup_misses+_lookup_hits)*4+100 >= _look_probes, "bad hash function");
     assert( _inserts+(_inserts>>3) < _max, "table too full" );
     assert( _inserts*3+100 >= _insert_probes, "bad hash function" );
   }
 }
 Node *NodeHash::find_index(uint idx) { // For debugging
   // Find an entry by its index value
   for( uint i = 0; i < _max; i++ ) {
     Node *m = _table[i];
     if( !m || m == _sentinel ) continue;
     if( m->_idx == (uint)idx ) return m;
   }
   return NULL;
 }
 #endif
 #ifdef ASSERT
 NodeHash::~NodeHash() {
   // Unlock all nodes upon destruction of table.
   if (_table != (Node**)badAddress)  clear();
 }
 void NodeHash::operator=(const NodeHash& nh) {
   // Unlock all nodes upon replacement of table.
   if (&nh == this)  return;
   if (_table != (Node**)badAddress)  clear();
   memcpy(this, &nh, sizeof(*this));
   // Do not increment hash_lock counts again.
   // Instead, be sure we never again use the source table.
   ((NodeHash*)&nh)->_table = (Node**)badAddress;
 }
 #endif
 //=============================================================================
 //------------------------------PhaseRemoveUseless-----------------------------
 // 1) Use a breadthfirst walk to collect useful nodes reachable from root.
 PhaseRemoveUseless::PhaseRemoveUseless( PhaseGVN *gvn, Unique_Node_List *worklist ) : Phase(Remove_Useless),
   _useful(Thread::current()->resource_area()) {
   // Implementation requires 'UseLoopSafepoints == true' and an edge from root
   // to each SafePointNode at a backward branch.  Inserted in add_safepoint().
   if( !UseLoopSafepoints || !OptoRemoveUseless ) return;
   // Identify nodes that are reachable from below, useful.
   C->identify_useful_nodes(_useful);
   // Remove all useless nodes from PhaseValues' recorded types
   // Must be done before disconnecting nodes to preserve hash-table-invariant
   gvn->remove_useless_nodes(_useful.member_set());
   // Remove all useless nodes from future worklist
   worklist->remove_useless_nodes(_useful.member_set());
   // Disconnect 'useless' nodes that are adjacent to useful nodes
   C->remove_useless_nodes(_useful);
   // Remove edges from "root" to each SafePoint at a backward branch.
   // They were inserted during parsing (see add_safepoint()) to make infinite
   // loops without calls or exceptions visible to root, i.e., useful.
   Node *root = C->root();
   if( root != NULL ) {
     for( uint i = root->req(); i < root->len(); ++i ) {
       Node *n = root->in(i);
       if( n != NULL && n->is_SafePoint() ) {
         root->rm_prec(i);
         --i;
       }
     }
   }
 }
 //=============================================================================
 //------------------------------PhaseTransform---------------------------------
 PhaseTransform::PhaseTransform( PhaseNumber pnum ) : Phase(pnum),
   _arena(Thread::current()->resource_area()),
   _nodes(_arena),
   _types(_arena)
 {
   init_con_caches();
 #ifndef PRODUCT
   clear_progress();
   clear_transforms();
   set_allow_progress(true);
 #endif
   // Force allocation for currently existing nodes
   _types.map(C->unique(), NULL);
 }
 //------------------------------PhaseTransform---------------------------------
 PhaseTransform::PhaseTransform( Arena *arena, PhaseNumber pnum ) : Phase(pnum),
   _arena(arena),
   _nodes(arena),
   _types(arena)
 {
   init_con_caches();
 #ifndef PRODUCT
   clear_progress();
   clear_transforms();
   set_allow_progress(true);
 #endif
   // Force allocation for currently existing nodes
   _types.map(C->unique(), NULL);
 }
 //------------------------------PhaseTransform---------------------------------
 // Initialize with previously generated type information
 PhaseTransform::PhaseTransform( PhaseTransform *pt, PhaseNumber pnum ) : Phase(pnum),
   _arena(pt->_arena),
   _nodes(pt->_nodes),
   _types(pt->_types)
 {
   init_con_caches();
 #ifndef PRODUCT
   clear_progress();
   clear_transforms();
   set_allow_progress(true);
 #endif
 }
 void PhaseTransform::init_con_caches() {
   memset(_icons,0,sizeof(_icons));
   memset(_lcons,0,sizeof(_lcons));
   memset(_zcons,0,sizeof(_zcons));
 }
 //--------------------------------find_int_type--------------------------------
 const TypeInt* PhaseTransform::find_int_type(Node* n) {
   if (n == NULL)  return NULL;
   // Call type_or_null(n) to determine node's type since we might be in
   // parse phase and call n->Value() may return wrong type.
   // (For example, a phi node at the beginning of loop parsing is not ready.)
   const Type* t = type_or_null(n);
   if (t == NULL)  return NULL;
   return t->isa_int();
 }
 //-------------------------------find_long_type--------------------------------
 const TypeLong* PhaseTransform::find_long_type(Node* n) {
   if (n == NULL)  return NULL;
   // (See comment above on type_or_null.)
   const Type* t = type_or_null(n);
   if (t == NULL)  return NULL;
   return t->isa_long();
 }
 #ifndef PRODUCT
 void PhaseTransform::dump_old2new_map() const {
   _nodes.dump();
 }
 void PhaseTransform::dump_new( uint nidx ) const {
   for( uint i=0; i<_nodes.Size(); i++ )
     if( _nodes[i] && _nodes[i]->_idx == nidx ) {
       _nodes[i]->dump();
       tty->cr();
       tty->print_cr("Old index= %d",i);
       return;
     }
   tty->print_cr("Node %d not found in the new indices", nidx);
 }
 //------------------------------dump_types-------------------------------------
 void PhaseTransform::dump_types( ) const {
   _types.dump();
 }
 //------------------------------dump_nodes_and_types---------------------------
 void PhaseTransform::dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl) {
   VectorSet visited(Thread::current()->resource_area());
   dump_nodes_and_types_recur( root, depth, only_ctrl, visited );
 }
 //------------------------------dump_nodes_and_types_recur---------------------
 void PhaseTransform::dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited) {
   if( !n ) return;
   if( depth == 0 ) return;
   if( visited.test_set(n->_idx) ) return;
   for( uint i=0; i<n->len(); i++ ) {
     if( only_ctrl && !(n->is_Region()) && i != TypeFunc::Control ) continue;
     dump_nodes_and_types_recur( n->in(i), depth-1, only_ctrl, visited );
   }
   n->dump();
   if (type_or_null(n) != NULL) {
     tty->print("      "); type(n)->dump(); tty->cr();
   }
 }
 #endif
 //=============================================================================
 //------------------------------PhaseValues------------------------------------
 // Set minimum table size to "255"
 PhaseValues::PhaseValues( Arena *arena, uint est_max_size ) : PhaseTransform(arena, GVN), _table(arena, est_max_size) {
   NOT_PRODUCT( clear_new_values(); )
 }
 //------------------------------PhaseValues------------------------------------
 // Set minimum table size to "255"
 PhaseValues::PhaseValues( PhaseValues *ptv ) : PhaseTransform( ptv, GVN ),
   _table(&ptv->_table) {
   NOT_PRODUCT( clear_new_values(); )
 }
 //------------------------------PhaseValues------------------------------------
 // Used by +VerifyOpto.  Clear out hash table but copy _types array.
 PhaseValues::PhaseValues( PhaseValues *ptv, const char *dummy ) : PhaseTransform( ptv, GVN ),
   _table(ptv->arena(),ptv->_table.size()) {
   NOT_PRODUCT( clear_new_values(); )
 }
 //------------------------------~PhaseValues-----------------------------------
 #ifndef PRODUCT
 PhaseValues::~PhaseValues() {
   _table.dump();
   // Statistics for value progress and efficiency
   if( PrintCompilation && Verbose && WizardMode ) {
     tty->print("\n%sValues: %d nodes ---> %d/%d (%d)",
       is_IterGVN() ? "Iter" : "    ", C->unique(), made_progress(), made_transforms(), made_new_values());
     if( made_transforms() != 0 ) {
       tty->print_cr("  ratio %f", made_progress()/(float)made_transforms() );
     } else {
       tty->cr();
     }
   }
 }
 #endif
 //------------------------------makecon----------------------------------------
 ConNode* PhaseTransform::makecon(const Type *t) {
   assert(t->singleton(), "must be a constant");
   assert(!t->empty() || t == Type::TOP, "must not be vacuous range");
   switch (t->base()) {  // fast paths
   case Type::Half:
   case Type::Top:  return (ConNode*) C->top();
   case Type::Int:  return intcon( t->is_int()->get_con() );
   case Type::Long: return longcon( t->is_long()->get_con() );
   }
   if (t->is_zero_type())
     return zerocon(t->basic_type());
   return uncached_makecon(t);
 }
 //--------------------------uncached_makecon-----------------------------------
 // Make an idealized constant - one of ConINode, ConPNode, etc.
 ConNode* PhaseValues::uncached_makecon(const Type *t) {
   assert(t->singleton(), "must be a constant");
   ConNode* x = ConNode::make(C, t);
   ConNode* k = (ConNode*)hash_find_insert(x); // Value numbering
   if (k == NULL) {
     set_type(x, t);             // Missed, provide type mapping
     GrowableArray<Node_Notes*>* nna = C->node_note_array();
     if (nna != NULL) {
       Node_Notes* loc = C->locate_node_notes(nna, x->_idx, true);
       loc->clear(); // do not put debug info on constants
     }
   } else {
     x->destruct();              // Hit, destroy duplicate constant
     x = k;                      // use existing constant
   }
   return x;
 }
 //------------------------------intcon-----------------------------------------
 // Fast integer constant.  Same as "transform(new ConINode(TypeInt::make(i)))"
 ConINode* PhaseTransform::intcon(int i) {
   // Small integer?  Check cache! Check that cached node is not dead
   if (i >= _icon_min && i <= _icon_max) {
     ConINode* icon = _icons[i-_icon_min];
     if (icon != NULL && icon->in(TypeFunc::Control) != NULL)
       return icon;
   }
   ConINode* icon = (ConINode*) uncached_makecon(TypeInt::make(i));
   assert(icon->is_Con(), "");
   if (i >= _icon_min && i <= _icon_max)
     _icons[i-_icon_min] = icon;   // Cache small integers
   return icon;
 }
 //------------------------------longcon----------------------------------------
 // Fast long constant.
 ConLNode* PhaseTransform::longcon(jlong l) {
   // Small integer?  Check cache! Check that cached node is not dead
   if (l >= _lcon_min && l <= _lcon_max) {
     ConLNode* lcon = _lcons[l-_lcon_min];
     if (lcon != NULL && lcon->in(TypeFunc::Control) != NULL)
       return lcon;
   }
   ConLNode* lcon = (ConLNode*) uncached_makecon(TypeLong::make(l));
   assert(lcon->is_Con(), "");
   if (l >= _lcon_min && l <= _lcon_max)
     _lcons[l-_lcon_min] = lcon;      // Cache small integers
   return lcon;
 }
 //------------------------------zerocon-----------------------------------------
 // Fast zero or null constant. Same as "transform(ConNode::make(Type::get_zero_type(bt)))"
 ConNode* PhaseTransform::zerocon(BasicType bt) {
   assert((uint)bt <= _zcon_max, "domain check");
   ConNode* zcon = _zcons[bt];
   if (zcon != NULL && zcon->in(TypeFunc::Control) != NULL)
     return zcon;
   zcon = (ConNode*) uncached_makecon(Type::get_zero_type(bt));
   _zcons[bt] = zcon;
   return zcon;
 }
 //=============================================================================
 //------------------------------transform--------------------------------------
 // Return a node which computes the same function as this node, but in a
 // faster or cheaper fashion.
 Node *PhaseGVN::transform( Node *n ) {
   return transform_no_reclaim(n);
 }
 //------------------------------transform--------------------------------------
 // Return a node which computes the same function as this node, but
 // in a faster or cheaper fashion.
 Node *PhaseGVN::transform_no_reclaim( Node *n ) {
   NOT_PRODUCT( set_transforms(); )
   // Apply the Ideal call in a loop until it no longer applies
   Node *k = n;
   NOT_PRODUCT( uint loop_count = 0; )
   while( 1 ) {
     Node *i = k->Ideal(this, /*can_reshape=*/false);
     if( !i ) break;
     assert( i->_idx >= k->_idx, "Idealize should return new nodes, use Identity to return old nodes" );
     k = i;
     assert(loop_count++ < K, "infinite loop in PhaseGVN::transform");
   }
   NOT_PRODUCT( if( loop_count != 0 ) { set_progress(); } )
   // If brand new node, make space in type array.
   ensure_type_or_null(k);
   // Since I just called 'Value' to compute the set of run-time values
   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
   // cache Value.  Later requests for the local phase->type of this Node can
   // use the cached Value instead of suffering with 'bottom_type'.
   const Type *t = k->Value(this); // Get runtime Value set
   assert(t != NULL, "value sanity");
   if (type_or_null(k) != t) {
 #ifndef PRODUCT
     // Do not count initial visit to node as a transformation
     if (type_or_null(k) == NULL) {
       inc_new_values();
       set_progress();
     }
 #endif
     set_type(k, t);
     // If k is a TypeNode, capture any more-precise type permanently into Node
     k->raise_bottom_type(t);
   }
   if( t->singleton() && !k->is_Con() ) {
     NOT_PRODUCT( set_progress(); )
     return makecon(t);          // Turn into a constant
   }
   // Now check for Identities
   Node *i = k->Identity(this);  // Look for a nearby replacement
   if( i != k ) {                // Found? Return replacement!
     NOT_PRODUCT( set_progress(); )
     return i;
   }
   // Global Value Numbering
   i = hash_find_insert(k);      // Insert if new
   if( i && (i != k) ) {
     // Return the pre-existing node
     NOT_PRODUCT( set_progress(); )
     return i;
   }
   // Return Idealized original
   return k;
 }
 #ifdef ASSERT
 //------------------------------dead_loop_check--------------------------------
 // Check for a simple dead loop when a data node references itself directly
 // or through an other data node excluding cons and phis.
 void PhaseGVN::dead_loop_check( Node *n ) {
   // Phi may reference itself in a loop
   if (n != NULL && !n->is_dead_loop_safe() && !n->is_CFG()) {
     // Do 2 levels check and only data inputs.
     bool no_dead_loop = true;
     uint cnt = n->req();
     for (uint i = 1; i < cnt && no_dead_loop; i++) {
       Node *in = n->in(i);
       if (in == n) {
         no_dead_loop = false;
       } else if (in != NULL && !in->is_dead_loop_safe()) {
         uint icnt = in->req();
         for (uint j = 1; j < icnt && no_dead_loop; j++) {
           if (in->in(j) == n || in->in(j) == in)
             no_dead_loop = false;
         }
       }
     }
     if (!no_dead_loop) n->dump(3);
     assert(no_dead_loop, "dead loop detected");
   }
 }
 #endif
 //=============================================================================
 //------------------------------PhaseIterGVN-----------------------------------
 // Initialize hash table to fresh and clean for +VerifyOpto
 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn, const char *dummy ) : PhaseGVN(igvn,dummy), _worklist( ),
                                                                       _delay_transform(false) {
 }
 //------------------------------PhaseIterGVN-----------------------------------
 // Initialize with previous PhaseIterGVN info; used by PhaseCCP
 PhaseIterGVN::PhaseIterGVN( PhaseIterGVN *igvn ) : PhaseGVN(igvn),
                                                    _worklist( igvn->_worklist ),
                                                    _delay_transform(igvn->_delay_transform)
 {
 }
 //------------------------------PhaseIterGVN-----------------------------------
 // Initialize with previous PhaseGVN info from Parser
 PhaseIterGVN::PhaseIterGVN( PhaseGVN *gvn ) : PhaseGVN(gvn),
                                               _worklist(*C->for_igvn()),
                                               _delay_transform(false)
 {
   uint max;
   // Dead nodes in the hash table inherited from GVN were not treated as
   // roots during def-use info creation; hence they represent an invisible
   // use.  Clear them out.
   max = _table.size();
   for( uint i = 0; i < max; ++i ) {
     Node *n = _table.at(i);
     if(n != NULL && n != _table.sentinel() && n->outcnt() == 0) {
       if( n->is_top() ) continue;
       assert( false, "Parse::remove_useless_nodes missed this node");
       hash_delete(n);
     }
   }
   // Any Phis or Regions on the worklist probably had uses that could not
   // make more progress because the uses were made while the Phis and Regions
   // were in half-built states.  Put all uses of Phis and Regions on worklist.
   max = _worklist.size();
   for( uint j = 0; j < max; j++ ) {
     Node *n = _worklist.at(j);
     uint uop = n->Opcode();
     if( uop == Op_Phi || uop == Op_Region ||
         n->is_Type() ||
         n->is_Mem() )
       add_users_to_worklist(n);
   }
 }
 #ifndef PRODUCT
 void PhaseIterGVN::verify_step(Node* n) {
   _verify_window[_verify_counter % _verify_window_size] = n;
   ++_verify_counter;
   ResourceMark rm;
   ResourceArea *area = Thread::current()->resource_area();
   VectorSet old_space(area), new_space(area);
   if (C->unique() < 1000 ||
 == _verify_counter % (C->unique() < 10000 ? 10 : 100)) {
     ++_verify_full_passes;
     Node::verify_recur(C->root(), -1, old_space, new_space);
   }
   const int verify_depth = 4;
   for ( int i = 0; i < _verify_window_size; i++ ) {
     Node* n = _verify_window[i];
     if ( n == NULL )  continue;
     if( n->in(0) == NodeSentinel ) {  // xform_idom
       _verify_window[i] = n->in(1);
       --i; continue;
     }
     // Typical fanout is 1-2, so this call visits about 6 nodes.
     Node::verify_recur(n, verify_depth, old_space, new_space);
   }
 }
 #endif
 //------------------------------init_worklist----------------------------------
 // Initialize worklist for each node.
 void PhaseIterGVN::init_worklist( Node *n ) {
   if( _worklist.member(n) ) return;
   _worklist.push(n);
   uint cnt = n->req();
   for( uint i =0 ; i < cnt; i++ ) {
     Node *m = n->in(i);
     if( m ) init_worklist(m);
   }
 }
 //------------------------------optimize---------------------------------------
 void PhaseIterGVN::optimize() {
   debug_only(uint num_processed  = 0;);
 #ifndef PRODUCT
   {
     _verify_counter = 0;
     _verify_full_passes = 0;
     for ( int i = 0; i < _verify_window_size; i++ ) {
       _verify_window[i] = NULL;
     }
   }
 #endif
   // Pull from worklist; transform node;
   // If node has changed: update edge info and put uses on worklist.
   while( _worklist.size() ) {
     Node *n  = _worklist.pop();
     if (TraceIterativeGVN && Verbose) {
       tty->print("  Pop ");
       NOT_PRODUCT( n->dump(); )
       debug_only(if( (num_processed++ % 100) == 0 ) _worklist.print_set();)
     }
     if (n->outcnt() != 0) {
 #ifndef PRODUCT
       uint wlsize = _worklist.size();
       const Type* oldtype = type_or_null(n);
 #endif //PRODUCT
       Node *nn = transform_old(n);
 #ifndef PRODUCT
       if (TraceIterativeGVN) {
         const Type* newtype = type_or_null(n);
         if (nn != n) {
           // print old node
           tty->print("< ");
           if (oldtype != newtype && oldtype != NULL) {
             oldtype->dump();
           }
           do { tty->print("\t"); } while (tty->position() < 16);
           tty->print("<");
           n->dump();
         }
         if (oldtype != newtype || nn != n) {
           // print new node and/or new type
           if (oldtype == NULL) {
             tty->print("* ");
           } else if (nn != n) {
             tty->print("> ");
           } else {
             tty->print("= ");
           }
           if (newtype == NULL) {
             tty->print("null");
           } else {
             newtype->dump();
           }
           do { tty->print("\t"); } while (tty->position() < 16);
           nn->dump();
         }
         if (Verbose && wlsize < _worklist.size()) {
           tty->print("  Push {");
           while (wlsize != _worklist.size()) {
             Node* pushed = _worklist.at(wlsize++);
             tty->print(" %d", pushed->_idx);
           }
           tty->print_cr(" }");
         }
       }
       if( VerifyIterativeGVN && nn != n ) {
         verify_step((Node*) NULL);  // ignore n, it might be subsumed
       }
 #endif
     } else if (!n->is_top()) {
       remove_dead_node(n);
     }
   }
 #ifndef PRODUCT
   C->verify_graph_edges();
   if( VerifyOpto && allow_progress() ) {
     // Must turn off allow_progress to enable assert and break recursion
     C->root()->verify();
     { // Check if any progress was missed using IterGVN
       // Def-Use info enables transformations not attempted in wash-pass
       // e.g. Region/Phi cleanup, ...
       // Null-check elision -- may not have reached fixpoint
       //                       do not propagate to dominated nodes
       ResourceMark rm;
       PhaseIterGVN igvn2(this,"Verify"); // Fresh and clean!
       // Fill worklist completely
       igvn2.init_worklist(C->root());
       igvn2.set_allow_progress(false);
       igvn2.optimize();
       igvn2.set_allow_progress(true);
     }
   }
   if ( VerifyIterativeGVN && PrintOpto ) {
     if ( _verify_counter == _verify_full_passes )
       tty->print_cr("VerifyIterativeGVN: %d transforms and verify passes",
                     _verify_full_passes);
     else
       tty->print_cr("VerifyIterativeGVN: %d transforms, %d full verify passes",
                   _verify_counter, _verify_full_passes);
   }
 #endif
 }
 //------------------register_new_node_with_optimizer---------------------------
 // Register a new node with the optimizer.  Update the types array, the def-use
 // info.  Put on worklist.
 Node* PhaseIterGVN::register_new_node_with_optimizer(Node* n, Node* orig) {
   set_type_bottom(n);
   _worklist.push(n);
   if (orig != NULL)  C->copy_node_notes_to(n, orig);
   return n;
 }
 //------------------------------transform--------------------------------------
 // Non-recursive: idealize Node 'n' with respect to its inputs and its value
 Node *PhaseIterGVN::transform( Node *n ) {
   if (_delay_transform) {
     // Register the node but don't optimize for now
     register_new_node_with_optimizer(n);
     return n;
   }
   // If brand new node, make space in type array, and give it a type.
   ensure_type_or_null(n);
   if (type_or_null(n) == NULL) {
     set_type_bottom(n);
   }
   return transform_old(n);
 }
 //------------------------------transform_old----------------------------------
 Node *PhaseIterGVN::transform_old( Node *n ) {
 #ifndef PRODUCT
   debug_only(uint loop_count = 0;);
   set_transforms();
 #endif
   // Remove 'n' from hash table in case it gets modified
   _table.hash_delete(n);
   if( VerifyIterativeGVN ) {
    assert( !_table.find_index(n->_idx), "found duplicate entry in table");
   }
   // Apply the Ideal call in a loop until it no longer applies
   Node *k = n;
   DEBUG_ONLY(dead_loop_check(k);)
   DEBUG_ONLY(bool is_new = (k->outcnt() == 0);)
   Node *i = k->Ideal(this, /*can_reshape=*/true);
   assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes");
 #ifndef PRODUCT
   if( VerifyIterativeGVN )
     verify_step(k);
   if( i && VerifyOpto ) {
     if( !allow_progress() ) {
       if (i->is_Add() && i->outcnt() == 1) {
         // Switched input to left side because this is the only use
       } else if( i->is_If() && (i->in(0) == NULL) ) {
         // This IF is dead because it is dominated by an equivalent IF When
         // dominating if changed, info is not propagated sparsely to 'this'
         // Propagating this info further will spuriously identify other
         // progress.
         return i;
       } else
         set_progress();
     } else
       set_progress();
   }
 #endif
   while( i ) {
 #ifndef PRODUCT
     debug_only( if( loop_count >= K ) i->dump(4); )
     assert(loop_count < K, "infinite loop in PhaseIterGVN::transform");
     debug_only( loop_count++; )
 #endif
     assert((i->_idx >= k->_idx) || i->is_top(), "Idealize should return new nodes, use Identity to return old nodes");
     // Made a change; put users of original Node on worklist
     add_users_to_worklist( k );
     // Replacing root of transform tree?
     if( k != i ) {
       // Make users of old Node now use new.
       subsume_node( k, i );
       k = i;
     }
     DEBUG_ONLY(dead_loop_check(k);)
     // Try idealizing again
     DEBUG_ONLY(is_new = (k->outcnt() == 0);)
     i = k->Ideal(this, /*can_reshape=*/true);
     assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes");
 #ifndef PRODUCT
     if( VerifyIterativeGVN )
       verify_step(k);
     if( i && VerifyOpto ) set_progress();
 #endif
   }
   // If brand new node, make space in type array.
   ensure_type_or_null(k);
   // See what kind of values 'k' takes on at runtime
   const Type *t = k->Value(this);
   assert(t != NULL, "value sanity");
   // Since I just called 'Value' to compute the set of run-time values
   // for this Node, and 'Value' is non-local (and therefore expensive) I'll
   // cache Value.  Later requests for the local phase->type of this Node can
   // use the cached Value instead of suffering with 'bottom_type'.
   if (t != type_or_null(k)) {
     NOT_PRODUCT( set_progress(); )
     NOT_PRODUCT( inc_new_values();)
     set_type(k, t);
     // If k is a TypeNode, capture any more-precise type permanently into Node
     k->raise_bottom_type(t);
     // Move users of node to worklist
     add_users_to_worklist( k );
   }
   // If 'k' computes a constant, replace it with a constant
   if( t->singleton() && !k->is_Con() ) {
     NOT_PRODUCT( set_progress(); )
     Node *con = makecon(t);     // Make a constant
     add_users_to_worklist( k );
     subsume_node( k, con );     // Everybody using k now uses con
     return con;
   }
   // Now check for Identities
   i = k->Identity(this);        // Look for a nearby replacement
   if( i != k ) {                // Found? Return replacement!
     NOT_PRODUCT( set_progress(); )
     add_users_to_worklist( k );
     subsume_node( k, i );       // Everybody using k now uses i
     return i;
   }
   // Global Value Numbering
   i = hash_find_insert(k);      // Check for pre-existing node
   if( i && (i != k) ) {
     // Return the pre-existing node if it isn't dead
     NOT_PRODUCT( set_progress(); )
     add_users_to_worklist( k );
     subsume_node( k, i );       // Everybody using k now uses i
     return i;
   }
   // Return Idealized original
   return k;
 }
 //---------------------------------saturate------------------------------------
 const Type* PhaseIterGVN::saturate(const Type* new_type, const Type* old_type,
                                    const Type* limit_type) const {
   return new_type->narrow(old_type);
 }
 //------------------------------remove_globally_dead_node----------------------
 // Kill a globally dead Node.  All uses are also globally dead and are
 // aggressively trimmed.
 void PhaseIterGVN::remove_globally_dead_node( Node *dead ) {
   assert(dead != C->root(), "killing root, eh?");
   if (dead->is_top())  return;
   NOT_PRODUCT( set_progress(); )
   // Remove from iterative worklist
   _worklist.remove(dead);
   if (!dead->is_Con()) { // Don't kill cons but uses
     // Remove from hash table
     _table.hash_delete( dead );
     // Smash all inputs to 'dead', isolating him completely
     for( uint i = 0; i < dead->req(); i++ ) {
       Node *in = dead->in(i);
       if( in ) {                 // Points to something?
         dead->set_req(i,NULL);  // Kill the edge
         if (in->outcnt() == 0 && in != C->top()) {// Made input go dead?
           remove_dead_node(in); // Recursively remove
         } else if (in->outcnt() == 1 &&
                    in->has_special_unique_user()) {
           _worklist.push(in->unique_out());
         } else if (in->outcnt() <= 2 && dead->is_Phi()) {
           if( in->Opcode() == Op_Region )
             _worklist.push(in);
           else if( in->is_Store() ) {
             DUIterator_Fast imax, i = in->fast_outs(imax);
             _worklist.push(in->fast_out(i));
             i++;
             if(in->outcnt() == 2) {
               _worklist.push(in->fast_out(i));
               i++;
             }
             assert(!(i < imax), "sanity");
           }
         }
       }
     }
     if (dead->is_macro()) {
       C->remove_macro_node(dead);
     }
   }
   // Aggressively kill globally dead uses
   // (Cannot use DUIterator_Last because of the indefinite number
   // of edge deletions per loop trip.)
   while (dead->outcnt() > 0) {
     remove_globally_dead_node(dead->raw_out(0));
   }
 }
 //------------------------------subsume_node-----------------------------------
 // Remove users from node 'old' and add them to node 'nn'.
 void PhaseIterGVN::subsume_node( Node *old, Node *nn ) {
   assert( old != hash_find(old), "should already been removed" );
   assert( old != C->top(), "cannot subsume top node");
   // Copy debug or profile information to the new version:
   C->copy_node_notes_to(nn, old);
   // Move users of node 'old' to node 'nn'
   for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) {
     Node* use = old->last_out(i);  // for each use...
     // use might need re-hashing (but it won't if it's a new node)
     bool is_in_table = _table.hash_delete( use );
     // Update use-def info as well
     // We remove all occurrences of old within use->in,
     // so as to avoid rehashing any node more than once.
     // The hash table probe swamps any outer loop overhead.
     uint num_edges = 0;
     for (uint jmax = use->len(), j = 0; j < jmax; j++) {
       if (use->in(j) == old) {
         use->set_req(j, nn);
         ++num_edges;
       }
     }
     // Insert into GVN hash table if unique
     // If a duplicate, 'use' will be cleaned up when pulled off worklist
     if( is_in_table ) {
       hash_find_insert(use);
     }
     i -= num_edges;    // we deleted 1 or more copies of this edge
   }
   // Smash all inputs to 'old', isolating him completely
   Node *temp = new (C, 1) Node(1);
   temp->init_req(0,nn);     // Add a use to nn to prevent him from dying
   remove_dead_node( old );
   temp->del_req(0);         // Yank bogus edge
 #ifndef PRODUCT
   if( VerifyIterativeGVN ) {
     for ( int i = 0; i < _verify_window_size; i++ ) {
       if ( _verify_window[i] == old )
         _verify_window[i] = nn;
     }
   }
 #endif
   _worklist.remove(temp);   // this can be necessary
   temp->destruct();         // reuse the _idx of this little guy
 }
 //------------------------------add_users_to_worklist--------------------------
 void PhaseIterGVN::add_users_to_worklist0( Node *n ) {
   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
     _worklist.push(n->fast_out(i));  // Push on worklist
   }
 }
 void PhaseIterGVN::add_users_to_worklist( Node *n ) {
   add_users_to_worklist0(n);
   // Move users of node to worklist
   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
     Node* use = n->fast_out(i); // Get use
     if( use->is_Multi() ||      // Multi-definer?  Push projs on worklist
         use->is_Store() )       // Enable store/load same address
       add_users_to_worklist0(use);
     // If we changed the receiver type to a call, we need to revisit
     // the Catch following the call.  It's looking for a non-NULL
     // receiver to know when to enable the regular fall-through path
     // in addition to the NullPtrException path.
     if (use->is_CallDynamicJava() && n == use->in(TypeFunc::Parms)) {
       Node* p = use->as_CallDynamicJava()->proj_out(TypeFunc::Control);
       if (p != NULL) {
         add_users_to_worklist0(p);
       }
     }
     if( use->is_Cmp() ) {       // Enable CMP/BOOL optimization
       add_users_to_worklist(use); // Put Bool on worklist
       // Look for the 'is_x2logic' pattern: "x ? : 0 : 1" and put the
       // phi merging either 0 or 1 onto the worklist
       if (use->outcnt() > 0) {
         Node* bol = use->raw_out(0);
         if (bol->outcnt() > 0) {
           Node* iff = bol->raw_out(0);
           if (iff->outcnt() == 2) {
             Node* ifproj0 = iff->raw_out(0);
             Node* ifproj1 = iff->raw_out(1);
             if (ifproj0->outcnt() > 0 && ifproj1->outcnt() > 0) {
               Node* region0 = ifproj0->raw_out(0);
               Node* region1 = ifproj1->raw_out(0);
               if( region0 == region1 )
                 add_users_to_worklist0(region0);
             }
           }
         }
       }
     }
     uint use_op = use->Opcode();
     // If changed Cast input, check Phi users for simple cycles
     if( use->is_ConstraintCast() || use->is_CheckCastPP() ) {
       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
         Node* u = use->fast_out(i2);
         if (u->is_Phi())
           _worklist.push(u);
       }
     }
     // If changed LShift inputs, check RShift users for useless sign-ext
     if( use_op == Op_LShiftI ) {
       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
         Node* u = use->fast_out(i2);
         if (u->Opcode() == Op_RShiftI)
           _worklist.push(u);
       }
     }
     // If changed AddP inputs, check Stores for loop invariant
     if( use_op == Op_AddP ) {
       for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
         Node* u = use->fast_out(i2);
         if (u->is_Mem())
           _worklist.push(u);
       }
     }
     // If changed initialization activity, check dependent Stores
     if (use_op == Op_Allocate || use_op == Op_AllocateArray) {
       InitializeNode* init = use->as_Allocate()->initialization();
       if (init != NULL) {
         Node* imem = init->proj_out(TypeFunc::Memory);
         if (imem != NULL)  add_users_to_worklist0(imem);
       }
     }
     if (use_op == Op_Initialize) {
       Node* imem = use->as_Initialize()->proj_out(TypeFunc::Memory);
       if (imem != NULL)  add_users_to_worklist0(imem);
     }
   }
 }
 //=============================================================================
 #ifndef PRODUCT
 uint PhaseCCP::_total_invokes   = 0;
 uint PhaseCCP::_total_constants = 0;
 #endif
 //------------------------------PhaseCCP---------------------------------------
 // Conditional Constant Propagation, ala Wegman & Zadeck
 PhaseCCP::PhaseCCP( PhaseIterGVN *igvn ) : PhaseIterGVN(igvn) {
   NOT_PRODUCT( clear_constants(); )
   assert( _worklist.size() == 0, "" );
   // Clear out _nodes from IterGVN.  Must be clear to transform call.
   _nodes.clear();               // Clear out from IterGVN
   analyze();
 }
 #ifndef PRODUCT
 //------------------------------~PhaseCCP--------------------------------------
 PhaseCCP::~PhaseCCP() {
   inc_invokes();
   _total_constants += count_constants();
 }
 #endif
 #ifdef ASSERT
 static bool ccp_type_widens(const Type* t, const Type* t0) {
   assert(t->meet(t0) == t, "Not monotonic");
   switch (t->base() == t0->base() ? t->base() : Type::Top) {
   case Type::Int:
     assert(t0->isa_int()->_widen <= t->isa_int()->_widen, "widen increases");
     break;
   case Type::Long:
     assert(t0->isa_long()->_widen <= t->isa_long()->_widen, "widen increases");
     break;
   }
   return true;
 }
 #endif //ASSERT
 //------------------------------analyze----------------------------------------
 void PhaseCCP::analyze() {
   // Initialize all types to TOP, optimistic analysis
   for (int i = C->unique() - 1; i >= 0; i--)  {
     _types.map(i,Type::TOP);
   }
   // Push root onto worklist
   Unique_Node_List worklist;
   worklist.push(C->root());
   // Pull from worklist; compute new value; push changes out.
   // This loop is the meat of CCP.
   while( worklist.size() ) {
     Node *n = worklist.pop();
     const Type *t = n->Value(this);
     if (t != type(n)) {
       assert(ccp_type_widens(t, type(n)), "ccp type must widen");
 #ifndef PRODUCT
       if( TracePhaseCCP ) {
         t->dump();
         do { tty->print("\t"); } while (tty->position() < 16);
         n->dump();
       }
 #endif
       set_type(n, t);
       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
         Node* m = n->fast_out(i);   // Get user
         if( m->is_Region() ) {  // New path to Region?  Must recheck Phis too
           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
             Node* p = m->fast_out(i2); // Propagate changes to uses
             if( p->bottom_type() != type(p) ) // If not already bottomed out
               worklist.push(p); // Propagate change to user
           }
         }
         // If we changed the receiver type to a call, we need to revisit
         // the Catch following the call.  It's looking for a non-NULL
         // receiver to know when to enable the regular fall-through path
         // in addition to the NullPtrException path
         if (m->is_Call()) {
           for (DUIterator_Fast i2max, i2 = m->fast_outs(i2max); i2 < i2max; i2++) {
             Node* p = m->fast_out(i2);  // Propagate changes to uses
             if (p->is_Proj() && p->as_Proj()->_con == TypeFunc::Control && p->outcnt() == 1)
               worklist.push(p->unique_out());
           }
         }
         if( m->bottom_type() != type(m) ) // If not already bottomed out
           worklist.push(m);     // Propagate change to user
       }
     }
   }
 }
 //------------------------------do_transform-----------------------------------
 // Top level driver for the recursive transformer
 void PhaseCCP::do_transform() {
   // Correct leaves of new-space Nodes; they point to old-space.
   C->set_root( transform(C->root())->as_Root() );
   assert( C->top(),  "missing TOP node" );
   assert( C->root(), "missing root" );
 }
 //------------------------------transform--------------------------------------
 // Given a Node in old-space, clone him into new-space.
 // Convert any of his old-space children into new-space children.
 Node *PhaseCCP::transform( Node *n ) {
   Node *new_node = _nodes[n->_idx]; // Check for transformed node
   if( new_node != NULL )
     return new_node;                // Been there, done that, return old answer
   new_node = transform_once(n);     // Check for constant
   _nodes.map( n->_idx, new_node );  // Flag as having been cloned
   // Allocate stack of size _nodes.Size()/2 to avoid frequent realloc
   GrowableArray <Node *> trstack(C->unique() >> 1);
   trstack.push(new_node);           // Process children of cloned node
   while ( trstack.is_nonempty() ) {
     Node *clone = trstack.pop();
     uint cnt = clone->req();
     for( uint i = 0; i < cnt; i++ ) {          // For all inputs do
       Node *input = clone->in(i);
       if( input != NULL ) {                    // Ignore NULLs
         Node *new_input = _nodes[input->_idx]; // Check for cloned input node
         if( new_input == NULL ) {
           new_input = transform_once(input);   // Check for constant
           _nodes.map( input->_idx, new_input );// Flag as having been cloned
           trstack.push(new_input);
         }
         assert( new_input == clone->in(i), "insanity check");
       }
     }
   }
   return new_node;
 }
 //------------------------------transform_once---------------------------------
 // For PhaseCCP, transformation is IDENTITY unless Node computed a constant.
 Node *PhaseCCP::transform_once( Node *n ) {
   const Type *t = type(n);
   // Constant?  Use constant Node instead
   if( t->singleton() ) {
     Node *nn = n;               // Default is to return the original constant
     if( t == Type::TOP ) {
       // cache my top node on the Compile instance
       if( C->cached_top_node() == NULL || C->cached_top_node()->in(0) == NULL ) {
         C->set_cached_top_node( ConNode::make(C, Type::TOP) );
         set_type(C->top(), Type::TOP);
       }
       nn = C->top();
     }
     if( !n->is_Con() ) {
       if( t != Type::TOP ) {
         nn = makecon(t);        // ConNode::make(t);
         NOT_PRODUCT( inc_constants(); )
       } else if( n->is_Region() ) { // Unreachable region
         // Note: nn == C->top()
         n->set_req(0, NULL);        // Cut selfreference
         // Eagerly remove dead phis to avoid phis copies creation.
         for (DUIterator i = n->outs(); n->has_out(i); i++) {
           Node* m = n->out(i);
           if( m->is_Phi() ) {
             assert(type(m) == Type::TOP, "Unreachable region should not have live phis.");
             add_users_to_worklist(m);
             hash_delete(m); // Yank from hash before hacking edges
             subsume_node(m, nn);
             --i; // deleted this phi; rescan starting with next position
           }
         }
       }
       add_users_to_worklist(n); // Users of about-to-be-constant 'n'
       hash_delete(n);           // Removed 'n' from table before subsuming it
       subsume_node(n,nn);       // Update DefUse edges for new constant
     }
     return nn;
   }
   // If x is a TypeNode, capture any more-precise type permanently into Node
   if (t != n->bottom_type()) {
     hash_delete(n);             // changing bottom type may force a rehash
     n->raise_bottom_type(t);
     _worklist.push(n);          // n re-enters the hash table via the worklist
   }
   // Idealize graph using DU info.  Must clone() into new-space.
   // DU info is generally used to show profitability, progress or safety
   // (but generally not needed for correctness).
   Node *nn = n->Ideal_DU_postCCP(this);
   // TEMPORARY fix to ensure that 2nd GVN pass eliminates NULL checks
   switch( n->Opcode() ) {
   case Op_FastLock:      // Revisit FastLocks for lock coarsening
   case Op_If:
   case Op_CountedLoopEnd:
   case Op_Region:
   case Op_Loop:
   case Op_CountedLoop:
   case Op_Conv2B:
   case Op_Opaque1:
   case Op_Opaque2:
     _worklist.push(n);
     break;
   default:
     break;
   }
   if( nn ) {
     _worklist.push(n);
     // Put users of 'n' onto worklist for second igvn transform
     add_users_to_worklist(n);
     return nn;
   }
   return  n;
 }
 //---------------------------------saturate------------------------------------
 const Type* PhaseCCP::saturate(const Type* new_type, const Type* old_type,
                                const Type* limit_type) const {
   const Type* wide_type = new_type->widen(old_type);
   if (wide_type != new_type) {          // did we widen?
     // If so, we may have widened beyond the limit type.  Clip it back down.
     new_type = wide_type->filter(limit_type);
   }
   return new_type;
 }
 //------------------------------print_statistics-------------------------------
 #ifndef PRODUCT
 void PhaseCCP::print_statistics() {
   tty->print_cr("CCP: %d  constants found: %d", _total_invokes, _total_constants);
 }
 #endif
 //=============================================================================
 #ifndef PRODUCT
 uint PhasePeephole::_total_peepholes = 0;
 #endif
 //------------------------------PhasePeephole----------------------------------
 // Conditional Constant Propagation, ala Wegman & Zadeck
 PhasePeephole::PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg )
   : PhaseTransform(Peephole), _regalloc(regalloc), _cfg(cfg) {
   NOT_PRODUCT( clear_peepholes(); )
 }
 #ifndef PRODUCT
 //------------------------------~PhasePeephole---------------------------------
 PhasePeephole::~PhasePeephole() {
   _total_peepholes += count_peepholes();
 }
 #endif
 //------------------------------transform--------------------------------------
 Node *PhasePeephole::transform( Node *n ) {
   ShouldNotCallThis();
   return NULL;
 }
 //------------------------------do_transform-----------------------------------
 void PhasePeephole::do_transform() {
   bool method_name_not_printed = true;
   // Examine each basic block
   for( uint block_number = 1; block_number < _cfg._num_blocks; ++block_number ) {
     Block *block = _cfg._blocks[block_number];
     bool block_not_printed = true;
     // and each instruction within a block
     uint end_index = block->_nodes.size();
     // block->end_idx() not valid after PhaseRegAlloc
     for( uint instruction_index = 1; instruction_index < end_index; ++instruction_index ) {
       Node     *n = block->_nodes.at(instruction_index);
       if( n->is_Mach() ) {
         MachNode *m = n->as_Mach();
         int deleted_count = 0;
         // check for peephole opportunities
         MachNode *m2 = m->peephole( block, instruction_index, _regalloc, deleted_count, C );
         if( m2 != NULL ) {
 #ifndef PRODUCT
           if( PrintOptoPeephole ) {
             // Print method, first time only
             if( C->method() && method_name_not_printed ) {
               C->method()->print_short_name(); tty->cr();
               method_name_not_printed = false;
             }
             // Print this block
             if( Verbose && block_not_printed) {
               tty->print_cr("in block");
               block->dump();
               block_not_printed = false;
             }
             // Print instructions being deleted
             for( int i = (deleted_count - 1); i >= 0; --i ) {
               block->_nodes.at(instruction_index-i)->as_Mach()->format(_regalloc); tty->cr();
             }
             tty->print_cr("replaced with");
             // Print new instruction
             m2->format(_regalloc);
             tty->print("\n\n");
           }
 #endif
           // Remove old nodes from basic block and update instruction_index
           // (old nodes still exist and may have edges pointing to them
           //  as register allocation info is stored in the allocator using
           //  the node index to live range mappings.)
           uint safe_instruction_index = (instruction_index - deleted_count);
           for( ; (instruction_index > safe_instruction_index); --instruction_index ) {
             block->_nodes.remove( instruction_index );
           }
           // install new node after safe_instruction_index
           block->_nodes.insert( safe_instruction_index + 1, m2 );
           end_index = block->_nodes.size() - 1; // Recompute new block size
           NOT_PRODUCT( inc_peepholes(); )
         }
       }
     }
   }
 }
 //------------------------------print_statistics-------------------------------
 #ifndef PRODUCT
 void PhasePeephole::print_statistics() {
   tty->print_cr("Peephole: peephole rules applied: %d",  _total_peepholes);
 }
 #endif
 //=============================================================================
 //------------------------------set_req_X--------------------------------------
 void Node::set_req_X( uint i, Node *n, PhaseIterGVN *igvn ) {
   assert( is_not_dead(n), "can not use dead node");
   assert( igvn->hash_find(this) != this, "Need to remove from hash before changing edges" );
   Node *old = in(i);
   set_req(i, n);
   // old goes dead?
   if( old ) {
     switch (old->outcnt()) {
     case 0:      // Kill all his inputs, and recursively kill other dead nodes.
       if (!old->is_top())
         igvn->remove_dead_node( old );
       break;
     case 1:
       if( old->is_Store() || old->has_special_unique_user() )
         igvn->add_users_to_worklist( old );
       break;
     case 2:
       if( old->is_Store() )
         igvn->add_users_to_worklist( old );
       if( old->Opcode() == Op_Region )
         igvn->_worklist.push(old);
       break;
     case 3:
       if( old->Opcode() == Op_Region ) {
         igvn->_worklist.push(old);
         igvn->add_users_to_worklist( old );
       }
       break;
     default:
       break;
     }
   }
 }
 //-------------------------------replace_by-----------------------------------
 // Using def-use info, replace one node for another.  Follow the def-use info
 // to all users of the OLD node.  Then make all uses point to the NEW node.
 void Node::replace_by(Node *new_node) {
   assert(!is_top(), "top node has no DU info");
   for (DUIterator_Last imin, i = last_outs(imin); i >= imin; ) {
     Node* use = last_out(i);
     uint uses_found = 0;
     for (uint j = 0; j < use->len(); j++) {
       if (use->in(j) == this) {
         if (j < use->req())
               use->set_req(j, new_node);
         else  use->set_prec(j, new_node);
         uses_found++;
       }
     }
     i -= uses_found;    // we deleted 1 or more copies of this edge
   }
 }
 //=============================================================================
 //-----------------------------------------------------------------------------
 void Type_Array::grow( uint i ) {
   if( !_max ) {
     _max = 1;
     _types = (const Type**)_a->Amalloc( _max * sizeof(Type*) );
     _types[0] = NULL;
   }
   uint old = _max;
   while( i >= _max ) _max <<= 1;        // Double to fit
   _types = (const Type**)_a->Arealloc( _types, old*sizeof(Type*),_max*sizeof(Type*));
   memset( &_types[old], 0, (_max-old)*sizeof(Type*) );
 }
 //------------------------------dump-------------------------------------------
 #ifndef PRODUCT
 void Type_Array::dump() const {
   uint max = Size();
   for( uint i = 0; i < max; i++ ) {
     if( _types[i] != NULL ) {
       tty->print("  %d\t== ", i); _types[i]->dump(); tty->cr();
     }
   }
 }
 #endif

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/opto/phaseX.cpp@98cb887364d3 (annotated)

src/share/vm/opto/phaseX.cpp