1 /*
   2  * Copyright (c) 1997, 2013, 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 #ifndef SHARE_VM_OPTO_PHASEX_HPP
  26 #define SHARE_VM_OPTO_PHASEX_HPP
  27 
  28 #include "libadt/dict.hpp"
  29 #include "libadt/vectset.hpp"
  30 #include "memory/resourceArea.hpp"
  31 #include "opto/memnode.hpp"
  32 #include "opto/node.hpp"
  33 #include "opto/phase.hpp"
  34 #include "opto/type.hpp"
  35 
  36 class Compile;
  37 class ConINode;
  38 class ConLNode;
  39 class Node;
  40 class Type;
  41 class PhaseTransform;
  42 class   PhaseGVN;
  43 class     PhaseIterGVN;
  44 class       PhaseCCP;
  45 class   PhasePeephole;
  46 class   PhaseRegAlloc;
  47 
  48 
  49 //-----------------------------------------------------------------------------
  50 // Expandable closed hash-table of nodes, initialized to NULL.
  51 // Note that the constructor just zeros things
  52 // Storage is reclaimed when the Arena's lifetime is over.
  53 class NodeHash : public StackObj {
  54 protected:
  55   Arena *_a;                    // Arena to allocate in
  56   uint   _max;                  // Size of table (power of 2)
  57   uint   _inserts;              // For grow and debug, count of hash_inserts
  58   uint   _insert_limit;         // 'grow' when _inserts reaches _insert_limit
  59   Node **_table;                // Hash table of Node pointers
  60   Node  *_sentinel;             // Replaces deleted entries in hash table
  61 
  62 public:
  63   NodeHash(uint est_max_size);
  64   NodeHash(Arena *arena, uint est_max_size);
  65   NodeHash(NodeHash *use_this_state);
  66 #ifdef ASSERT
  67   ~NodeHash();                  // Unlock all nodes upon destruction of table.
  68   void operator=(const NodeHash&); // Unlock all nodes upon replacement of table.
  69 #endif
  70   Node  *hash_find(const Node*);// Find an equivalent version in hash table
  71   Node  *hash_find_insert(Node*);// If not in table insert else return found node
  72   void   hash_insert(Node*);    // Insert into hash table
  73   bool   hash_delete(const Node*);// Replace with _sentinel in hash table
  74   void   check_grow() {
  75     _inserts++;
  76     if( _inserts == _insert_limit ) { grow(); }
  77     assert( _inserts <= _insert_limit, "hash table overflow");
  78     assert( _inserts < _max, "hash table overflow" );
  79   }
  80   static uint round_up(uint);   // Round up to nearest power of 2
  81   void   grow();                // Grow _table to next power of 2 and rehash
  82   // Return 75% of _max, rounded up.
  83   uint   insert_limit() const { return _max - (_max>>2); }
  84 
  85   void   clear();               // Set all entries to NULL, keep storage.
  86   // Size of hash table
  87   uint   size()         const { return _max; }
  88   // Return Node* at index in table
  89   Node  *at(uint table_index) {
  90     assert(table_index < _max, "Must be within table");
  91     return _table[table_index];
  92   }
  93 
  94   void   remove_useless_nodes(VectorSet &useful); // replace with sentinel
  95   void   replace_with(NodeHash* nh);
  96   void   check_no_speculative_types(); // Check no speculative part for type nodes in table
  97 
  98   Node  *sentinel() { return _sentinel; }
  99 
 100 #ifndef PRODUCT
 101   Node  *find_index(uint idx);  // For debugging
 102   void   dump();                // For debugging, dump statistics
 103   uint   _grows;                // For debugging, count of table grow()s
 104   uint   _look_probes;          // For debugging, count of hash probes
 105   uint   _lookup_hits;          // For debugging, count of hash_finds
 106   uint   _lookup_misses;        // For debugging, count of hash_finds
 107   uint   _insert_probes;        // For debugging, count of hash probes
 108   uint   _delete_probes;        // For debugging, count of hash probes for deletes
 109   uint   _delete_hits;          // For debugging, count of hash probes for deletes
 110   uint   _delete_misses;        // For debugging, count of hash probes for deletes
 111   uint   _total_inserts;        // For debugging, total inserts into hash table
 112   uint   _total_insert_probes;  // For debugging, total probes while inserting
 113 #endif
 114 };
 115 
 116 
 117 //-----------------------------------------------------------------------------
 118 // Map dense integer indices to Types.  Uses classic doubling-array trick.
 119 // Abstractly provides an infinite array of Type*'s, initialized to NULL.
 120 // Note that the constructor just zeros things, and since I use Arena
 121 // allocation I do not need a destructor to reclaim storage.
 122 // Despite the general name, this class is customized for use by PhaseTransform.
 123 class Type_Array : public StackObj {
 124   Arena *_a;                    // Arena to allocate in
 125   uint   _max;
 126   const Type **_types;
 127   void grow( uint i );          // Grow array node to fit
 128   const Type *operator[] ( uint i ) const // Lookup, or NULL for not mapped
 129   { return (i<_max) ? _types[i] : (Type*)NULL; }
 130   friend class PhaseTransform;
 131 public:
 132   Type_Array(Arena *a) : _a(a), _max(0), _types(0) {}
 133   Type_Array(Type_Array *ta) : _a(ta->_a), _max(ta->_max), _types(ta->_types) { }
 134   const Type *fast_lookup(uint i) const{assert(i<_max,"oob");return _types[i];}
 135   // Extend the mapping: index i maps to Type *n.
 136   void map( uint i, const Type *n ) { if( i>=_max ) grow(i); _types[i] = n; }
 137   uint Size() const { return _max; }
 138 #ifndef PRODUCT
 139   void dump() const;
 140 #endif
 141 };
 142 
 143 
 144 //------------------------------PhaseRemoveUseless-----------------------------
 145 // Remove useless nodes from GVN hash-table, worklist, and graph
 146 class PhaseRemoveUseless : public Phase {
 147 protected:
 148   Unique_Node_List _useful;   // Nodes reachable from root
 149                               // list is allocated from current resource area
 150 public:
 151   PhaseRemoveUseless(PhaseGVN *gvn, Unique_Node_List *worklist, PhaseNumber phase_num = Remove_Useless);
 152 
 153   Unique_Node_List *get_useful() { return &_useful; }
 154 };
 155 
 156 //------------------------------PhaseRenumber----------------------------------
 157 // Phase that first performs a PhaseRemoveUseless, then it renumbers compiler
 158 // structures accordingly.
 159 class PhaseRenumberLive : public PhaseRemoveUseless {
 160 public:
 161   PhaseRenumberLive(PhaseGVN* gvn,
 162                     Unique_Node_List* worklist, Unique_Node_List* new_worklist,
 163                     PhaseNumber phase_num = Remove_Useless_And_Renumber_Live);
 164 };
 165 
 166 
 167 //------------------------------PhaseTransform---------------------------------
 168 // Phases that analyze, then transform.  Constructing the Phase object does any
 169 // global or slow analysis.  The results are cached later for a fast
 170 // transformation pass.  When the Phase object is deleted the cached analysis
 171 // results are deleted.
 172 class PhaseTransform : public Phase {
 173 protected:
 174   Arena*     _arena;
 175   Node_List  _nodes;           // Map old node indices to new nodes.
 176   Type_Array _types;           // Map old node indices to Types.
 177 
 178   // ConNode caches:
 179   enum { _icon_min = -1 * HeapWordSize,
 180          _icon_max = 16 * HeapWordSize,
 181          _lcon_min = _icon_min,
 182          _lcon_max = _icon_max,
 183          _zcon_max = (uint)T_CONFLICT
 184   };
 185   ConINode* _icons[_icon_max - _icon_min + 1];   // cached jint constant nodes
 186   ConLNode* _lcons[_lcon_max - _lcon_min + 1];   // cached jlong constant nodes
 187   ConNode*  _zcons[_zcon_max + 1];               // cached is_zero_type nodes
 188   void init_con_caches();
 189 
 190   // Support both int and long caches because either might be an intptr_t,
 191   // so they show up frequently in address computations.
 192 
 193 public:
 194   PhaseTransform( PhaseNumber pnum );
 195   PhaseTransform( Arena *arena, PhaseNumber pnum );
 196   PhaseTransform( PhaseTransform *phase, PhaseNumber pnum );
 197 
 198   Arena*      arena()   { return _arena; }
 199   Type_Array& types()   { return _types; }
 200   void replace_types(Type_Array new_types) {
 201     _types = new_types;
 202   }
 203   // _nodes is used in varying ways by subclasses, which define local accessors
 204   uint nodes_size() {
 205     return _nodes.size();
 206   }
 207 
 208 public:
 209   // Get a previously recorded type for the node n.
 210   // This type must already have been recorded.
 211   // If you want the type of a very new (untransformed) node,
 212   // you must use type_or_null, and test the result for NULL.
 213   const Type* type(const Node* n) const {
 214     assert(_pnum != Ideal_Loop, "should not be used from PhaseIdealLoop");
 215     assert(n != NULL, "must not be null");
 216     const Type* t = _types.fast_lookup(n->_idx);
 217     assert(t != NULL, "must set before get");
 218     return t;
 219   }
 220   // Get a previously recorded type for the node n,
 221   // or else return NULL if there is none.
 222   const Type* type_or_null(const Node* n) const {
 223     assert(_pnum != Ideal_Loop, "should not be used from PhaseIdealLoop");
 224     return _types.fast_lookup(n->_idx);
 225   }
 226   // Record a type for a node.
 227   void    set_type(const Node* n, const Type *t) {
 228     assert(t != NULL, "type must not be null");
 229     _types.map(n->_idx, t);
 230   }
 231   // Record an initial type for a node, the node's bottom type.
 232   void    set_type_bottom(const Node* n) {
 233     // Use this for initialization when bottom_type() (or better) is not handy.
 234     // Usually the initialization shoudl be to n->Value(this) instead,
 235     // or a hand-optimized value like Type::MEMORY or Type::CONTROL.
 236     assert(_types[n->_idx] == NULL, "must set the initial type just once");
 237     _types.map(n->_idx, n->bottom_type());
 238   }
 239   // Make sure the types array is big enough to record a size for the node n.
 240   // (In product builds, we never want to do range checks on the types array!)
 241   void ensure_type_or_null(const Node* n) {
 242     if (n->_idx >= _types.Size())
 243       _types.map(n->_idx, NULL);   // Grow the types array as needed.
 244   }
 245 
 246   // Utility functions:
 247   const TypeInt*  find_int_type( Node* n);
 248   const TypeLong* find_long_type(Node* n);
 249   jint  find_int_con( Node* n, jint  value_if_unknown) {
 250     const TypeInt* t = find_int_type(n);
 251     return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
 252   }
 253   jlong find_long_con(Node* n, jlong value_if_unknown) {
 254     const TypeLong* t = find_long_type(n);
 255     return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
 256   }
 257 
 258   // Make an idealized constant, i.e., one of ConINode, ConPNode, ConFNode, etc.
 259   // Same as transform(ConNode::make(t)).
 260   ConNode* makecon(const Type* t);
 261   virtual ConNode* uncached_makecon(const Type* t)  // override in PhaseValues
 262   { ShouldNotCallThis(); return NULL; }
 263 
 264   // Fast int or long constant.  Same as TypeInt::make(i) or TypeLong::make(l).
 265   ConINode* intcon(jint i);
 266   ConLNode* longcon(jlong l);
 267 
 268   // Fast zero or null constant.  Same as makecon(Type::get_zero_type(bt)).
 269   ConNode* zerocon(BasicType bt);
 270 
 271   // Return a node which computes the same function as this node, but
 272   // in a faster or cheaper fashion.
 273   virtual Node *transform( Node *n ) = 0;
 274 
 275   // Return whether two Nodes are equivalent.
 276   // Must not be recursive, since the recursive version is built from this.
 277   // For pessimistic optimizations this is simply pointer equivalence.
 278   bool eqv(const Node* n1, const Node* n2) const { return n1 == n2; }
 279 
 280   // For pessimistic passes, the return type must monotonically narrow.
 281   // For optimistic  passes, the return type must monotonically widen.
 282   // It is possible to get into a "death march" in either type of pass,
 283   // where the types are continually moving but it will take 2**31 or
 284   // more steps to converge.  This doesn't happen on most normal loops.
 285   //
 286   // Here is an example of a deadly loop for an optimistic pass, along
 287   // with a partial trace of inferred types:
 288   //    x = phi(0,x'); L: x' = x+1; if (x' >= 0) goto L;
 289   //    0                 1                join([0..max], 1)
 290   //    [0..1]            [1..2]           join([0..max], [1..2])
 291   //    [0..2]            [1..3]           join([0..max], [1..3])
 292   //      ... ... ...
 293   //    [0..max]          [min]u[1..max]   join([0..max], [min..max])
 294   //    [0..max] ==> fixpoint
 295   // We would have proven, the hard way, that the iteration space is all
 296   // non-negative ints, with the loop terminating due to 32-bit overflow.
 297   //
 298   // Here is the corresponding example for a pessimistic pass:
 299   //    x = phi(0,x'); L: x' = x-1; if (x' >= 0) goto L;
 300   //    int               int              join([0..max], int)
 301   //    [0..max]          [-1..max-1]      join([0..max], [-1..max-1])
 302   //    [0..max-1]        [-1..max-2]      join([0..max], [-1..max-2])
 303   //      ... ... ...
 304   //    [0..1]            [-1..0]          join([0..max], [-1..0])
 305   //    0                 -1               join([0..max], -1)
 306   //    0 == fixpoint
 307   // We would have proven, the hard way, that the iteration space is {0}.
 308   // (Usually, other optimizations will make the "if (x >= 0)" fold up
 309   // before we get into trouble.  But not always.)
 310   //
 311   // It's a pleasant thing to observe that the pessimistic pass
 312   // will make short work of the optimistic pass's deadly loop,
 313   // and vice versa.  That is a good example of the complementary
 314   // purposes of the CCP (optimistic) vs. GVN (pessimistic) phases.
 315   //
 316   // In any case, only widen or narrow a few times before going to the
 317   // correct flavor of top or bottom.
 318   //
 319   // This call only needs to be made once as the data flows around any
 320   // given cycle.  We do it at Phis, and nowhere else.
 321   // The types presented are the new type of a phi (computed by PhiNode::Value)
 322   // and the previously computed type, last time the phi was visited.
 323   //
 324   // The third argument is upper limit for the saturated value,
 325   // if the phase wishes to widen the new_type.
 326   // If the phase is narrowing, the old type provides a lower limit.
 327   // Caller guarantees that old_type and new_type are no higher than limit_type.
 328   virtual const Type* saturate(const Type* new_type, const Type* old_type,
 329                                const Type* limit_type) const
 330   { ShouldNotCallThis(); return NULL; }
 331 
 332   // Delayed node rehash if this is an IGVN phase
 333   virtual void igvn_rehash_node_delayed(Node* n) {}
 334 
 335   // true if CFG node d dominates CFG node n
 336   virtual bool is_dominator(Node *d, Node *n) { fatal("unimplemented for this pass"); return false; };
 337 
 338 #ifndef PRODUCT
 339   void dump_old2new_map() const;
 340   void dump_new( uint new_lidx ) const;
 341   void dump_types() const;
 342   void dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl = true);
 343   void dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited);
 344 
 345   uint   _count_progress;       // For profiling, count transforms that make progress
 346   void   set_progress()        { ++_count_progress; assert( allow_progress(),"No progress allowed during verification"); }
 347   void   clear_progress()      { _count_progress = 0; }
 348   uint   made_progress() const { return _count_progress; }
 349 
 350   uint   _count_transforms;     // For profiling, count transforms performed
 351   void   set_transforms()      { ++_count_transforms; }
 352   void   clear_transforms()    { _count_transforms = 0; }
 353   uint   made_transforms() const{ return _count_transforms; }
 354 
 355   bool   _allow_progress;      // progress not allowed during verification pass
 356   void   set_allow_progress(bool allow) { _allow_progress = allow; }
 357   bool   allow_progress()               { return _allow_progress; }
 358 #endif
 359 };
 360 
 361 //------------------------------PhaseValues------------------------------------
 362 // Phase infrastructure to support values
 363 class PhaseValues : public PhaseTransform {
 364 protected:
 365   NodeHash  _table;             // Hash table for value-numbering
 366 
 367 public:
 368   PhaseValues( Arena *arena, uint est_max_size );
 369   PhaseValues( PhaseValues *pt );
 370   PhaseValues( PhaseValues *ptv, const char *dummy );
 371   NOT_PRODUCT( ~PhaseValues(); )
 372   virtual PhaseIterGVN *is_IterGVN() { return 0; }
 373 
 374   // Some Ideal and other transforms delete --> modify --> insert values
 375   bool   hash_delete(Node *n)     { return _table.hash_delete(n); }
 376   void   hash_insert(Node *n)     { _table.hash_insert(n); }
 377   Node  *hash_find_insert(Node *n){ return _table.hash_find_insert(n); }
 378   Node  *hash_find(const Node *n) { return _table.hash_find(n); }
 379 
 380   // Used after parsing to eliminate values that are no longer in program
 381   void   remove_useless_nodes(VectorSet &useful) {
 382     _table.remove_useless_nodes(useful);
 383     // this may invalidate cached cons so reset the cache
 384     init_con_caches();
 385   }
 386 
 387   virtual ConNode* uncached_makecon(const Type* t);  // override from PhaseTransform
 388 
 389   virtual const Type* saturate(const Type* new_type, const Type* old_type,
 390                                const Type* limit_type) const
 391   { return new_type; }
 392 
 393 #ifndef PRODUCT
 394   uint   _count_new_values;     // For profiling, count new values produced
 395   void    inc_new_values()        { ++_count_new_values; }
 396   void    clear_new_values()      { _count_new_values = 0; }
 397   uint    made_new_values() const { return _count_new_values; }
 398 #endif
 399 };
 400 
 401 
 402 //------------------------------PhaseGVN---------------------------------------
 403 // Phase for performing local, pessimistic GVN-style optimizations.
 404 class PhaseGVN : public PhaseValues {
 405 protected:
 406   bool is_dominator_helper(Node *d, Node *n, bool linear_only);
 407 
 408 public:
 409   PhaseGVN( Arena *arena, uint est_max_size ) : PhaseValues( arena, est_max_size ) {}
 410   PhaseGVN( PhaseGVN *gvn ) : PhaseValues( gvn ) {}
 411   PhaseGVN( PhaseGVN *gvn, const char *dummy ) : PhaseValues( gvn, dummy ) {}
 412 
 413   // Return a node which computes the same function as this node, but
 414   // in a faster or cheaper fashion.
 415   Node  *transform( Node *n );
 416   Node  *transform_no_reclaim( Node *n );
 417   virtual void record_for_igvn(Node *n) {
 418     C->record_for_igvn(n);
 419   }
 420 
 421   void replace_with(PhaseGVN* gvn) {
 422     _table.replace_with(&gvn->_table);
 423     _types = gvn->_types;
 424   }
 425 
 426   bool is_dominator(Node *d, Node *n) { return is_dominator_helper(d, n, true); }
 427 






 428   // Check for a simple dead loop when a data node references itself.
 429   DEBUG_ONLY(void dead_loop_check(Node *n);)
 430 };
 431 
 432 //------------------------------PhaseIterGVN-----------------------------------
 433 // Phase for iteratively performing local, pessimistic GVN-style optimizations.
 434 // and ideal transformations on the graph.
 435 class PhaseIterGVN : public PhaseGVN {
 436 private:
 437   bool _delay_transform;  // When true simply register the node when calling transform
 438                           // instead of actually optimizing it
 439 
 440   // Idealize old Node 'n' with respect to its inputs and its value
 441   virtual Node *transform_old( Node *a_node );
 442 
 443   // Subsume users of node 'old' into node 'nn'
 444   void subsume_node( Node *old, Node *nn );
 445 
 446   Node_Stack _stack;      // Stack used to avoid recursion
 447 
 448 protected:
 449 
 450   // Warm up hash table, type table and initial worklist
 451   void init_worklist( Node *a_root );
 452 
 453   virtual const Type* saturate(const Type* new_type, const Type* old_type,
 454                                const Type* limit_type) const;
 455   // Usually returns new_type.  Returns old_type if new_type is only a slight
 456   // improvement, such that it would take many (>>10) steps to reach 2**32.
 457 
 458 public:
 459   PhaseIterGVN( PhaseIterGVN *igvn ); // Used by CCP constructor
 460   PhaseIterGVN( PhaseGVN *gvn ); // Used after Parser
 461   PhaseIterGVN( PhaseIterGVN *igvn, const char *dummy ); // Used after +VerifyOpto
 462 
 463   // Idealize new Node 'n' with respect to its inputs and its value
 464   virtual Node *transform( Node *a_node );
 465   virtual void record_for_igvn(Node *n) { }
 466 
 467   virtual PhaseIterGVN *is_IterGVN() { return this; }
 468 
 469   Unique_Node_List _worklist;       // Iterative worklist
 470 
 471   // Given def-use info and an initial worklist, apply Node::Ideal,
 472   // Node::Value, Node::Identity, hash-based value numbering, Node::Ideal_DU
 473   // and dominator info to a fixed point.
 474   void optimize();
 475 
 476 #ifndef PRODUCT
 477   void trace_PhaseIterGVN(Node* n, Node* nn, const Type* old_type);
 478   void init_verifyPhaseIterGVN();
 479   void verify_PhaseIterGVN();
 480 #endif
 481 
 482 #ifdef ASSERT
 483   void dump_infinite_loop_info(Node* n);
 484   void trace_PhaseIterGVN_verbose(Node* n, int num_processed);
 485 #endif
 486 
 487   // Register a new node with the iter GVN pass without transforming it.
 488   // Used when we need to restructure a Region/Phi area and all the Regions
 489   // and Phis need to complete this one big transform before any other
 490   // transforms can be triggered on the region.
 491   // Optional 'orig' is an earlier version of this node.
 492   // It is significant only for debugging and profiling.
 493   Node* register_new_node_with_optimizer(Node* n, Node* orig = NULL);
 494 
 495   // Kill a globally dead Node.  All uses are also globally dead and are
 496   // aggressively trimmed.
 497   void remove_globally_dead_node( Node *dead );
 498 
 499   // Kill all inputs to a dead node, recursively making more dead nodes.
 500   // The Node must be dead locally, i.e., have no uses.
 501   void remove_dead_node( Node *dead ) {
 502     assert(dead->outcnt() == 0 && !dead->is_top(), "node must be dead");
 503     remove_globally_dead_node(dead);
 504   }
 505 
 506   // Add users of 'n' to worklist
 507   void add_users_to_worklist0( Node *n );
 508   void add_users_to_worklist ( Node *n );
 509 
 510   // Replace old node with new one.
 511   void replace_node( Node *old, Node *nn ) {
 512     add_users_to_worklist(old);
 513     hash_delete(old); // Yank from hash before hacking edges
 514     subsume_node(old, nn);
 515   }
 516 
 517   // Delayed node rehash: remove a node from the hash table and rehash it during
 518   // next optimizing pass
 519   void rehash_node_delayed(Node* n) {
 520     hash_delete(n);
 521     _worklist.push(n);
 522   }
 523 
 524   void igvn_rehash_node_delayed(Node* n) {
 525     rehash_node_delayed(n);
 526   }
 527 
 528   // Replace ith edge of "n" with "in"
 529   void replace_input_of(Node* n, int i, Node* in) {
 530     rehash_node_delayed(n);
 531     n->set_req(i, in);
 532   }
 533 
 534   // Delete ith edge of "n"
 535   void delete_input_of(Node* n, int i) {
 536     rehash_node_delayed(n);
 537     n->del_req(i);
 538   }
 539 
 540   bool delay_transform() const { return _delay_transform; }
 541 
 542   void set_delay_transform(bool delay) {
 543     _delay_transform = delay;
 544   }
 545 
 546   // Clone loop predicates. Defined in loopTransform.cpp.
 547   Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
 548   // Create a new if below new_entry for the predicate to be cloned
 549   ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
 550                                         Deoptimization::DeoptReason reason,
 551                                         int opcode);
 552 
 553   void remove_speculative_types();
 554   void check_no_speculative_types() {
 555     _table.check_no_speculative_types();
 556   }
 557 
 558   bool is_dominator(Node *d, Node *n) { return is_dominator_helper(d, n, false); }
 559 
 560 #ifndef PRODUCT
 561 protected:
 562   // Sub-quadratic implementation of VerifyIterativeGVN.
 563   julong _verify_counter;
 564   julong _verify_full_passes;
 565   enum { _verify_window_size = 30 };
 566   Node* _verify_window[_verify_window_size];
 567   void verify_step(Node* n);
 568 #endif
 569 };
 570 
 571 //------------------------------PhaseCCP---------------------------------------
 572 // Phase for performing global Conditional Constant Propagation.
 573 // Should be replaced with combined CCP & GVN someday.
 574 class PhaseCCP : public PhaseIterGVN {
 575   // Non-recursive.  Use analysis to transform single Node.
 576   virtual Node *transform_once( Node *n );
 577 
 578 public:
 579   PhaseCCP( PhaseIterGVN *igvn ); // Compute conditional constants
 580   NOT_PRODUCT( ~PhaseCCP(); )
 581 
 582   // Worklist algorithm identifies constants
 583   void analyze();
 584   // Recursive traversal of program.  Used analysis to modify program.
 585   virtual Node *transform( Node *n );
 586   // Do any transformation after analysis
 587   void          do_transform();
 588 
 589   virtual const Type* saturate(const Type* new_type, const Type* old_type,
 590                                const Type* limit_type) const;
 591   // Returns new_type->widen(old_type), which increments the widen bits until
 592   // giving up with TypeInt::INT or TypeLong::LONG.
 593   // Result is clipped to limit_type if necessary.
 594 
 595 #ifndef PRODUCT
 596   static uint _total_invokes;    // For profiling, count invocations
 597   void    inc_invokes()          { ++PhaseCCP::_total_invokes; }
 598 
 599   static uint _total_constants;  // For profiling, count constants found
 600   uint   _count_constants;
 601   void    clear_constants()      { _count_constants = 0; }
 602   void    inc_constants()        { ++_count_constants; }
 603   uint    count_constants() const { return _count_constants; }
 604 
 605   static void print_statistics();
 606 #endif
 607 };
 608 
 609 
 610 //------------------------------PhasePeephole----------------------------------
 611 // Phase for performing peephole optimizations on register allocated basic blocks.
 612 class PhasePeephole : public PhaseTransform {
 613   PhaseRegAlloc *_regalloc;
 614   PhaseCFG     &_cfg;
 615   // Recursive traversal of program.  Pure function is unused in this phase
 616   virtual Node *transform( Node *n );
 617 
 618 public:
 619   PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg );
 620   NOT_PRODUCT( ~PhasePeephole(); )
 621 
 622   // Do any transformation after analysis
 623   void          do_transform();
 624 
 625 #ifndef PRODUCT
 626   static uint _total_peepholes;  // For profiling, count peephole rules applied
 627   uint   _count_peepholes;
 628   void    clear_peepholes()      { _count_peepholes = 0; }
 629   void    inc_peepholes()        { ++_count_peepholes; }
 630   uint    count_peepholes() const { return _count_peepholes; }
 631 
 632   static void print_statistics();
 633 #endif
 634 };
 635 
 636 #endif // SHARE_VM_OPTO_PHASEX_HPP
--- EOF ---