text: /*
   * Copyright (c) 1997, 2013, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   *
   */
  
  #ifndef SHARE_VM_OPTO_PHASEX_HPP
  #define SHARE_VM_OPTO_PHASEX_HPP
  
  #include "libadt/dict.hpp"
  #include "libadt/vectset.hpp"
  #include "memory/resourceArea.hpp"
  #include "opto/memnode.hpp"
  #include "opto/node.hpp"
  #include "opto/phase.hpp"
  #include "opto/type.hpp"
  
  class Compile;
  class ConINode;
  class ConLNode;
  class Node;
  class Type;
  class PhaseTransform;
  class   PhaseGVN;
  class     PhaseIterGVN;
  class       PhaseCCP;
  class   PhasePeephole;
  class   PhaseRegAlloc;
  
  
  //-----------------------------------------------------------------------------
  // Expandable closed hash-table of nodes, initialized to NULL.
  // Note that the constructor just zeros things
  // Storage is reclaimed when the Arena's lifetime is over.
  class NodeHash : public StackObj {
  protected:
    Arena *_a;                    // Arena to allocate in
    uint   _max;                  // Size of table (power of 2)
    uint   _inserts;              // For grow and debug, count of hash_inserts
    uint   _insert_limit;         // 'grow' when _inserts reaches _insert_limit
    Node **_table;                // Hash table of Node pointers
    Node  *_sentinel;             // Replaces deleted entries in hash table
  
  public:
    NodeHash(uint est_max_size);
    NodeHash(Arena *arena, uint est_max_size);
    NodeHash(NodeHash *use_this_state);
  #ifdef ASSERT
    ~NodeHash();                  // Unlock all nodes upon destruction of table.
    void operator=(const NodeHash&); // Unlock all nodes upon replacement of table.
  #endif
    Node  *hash_find(const Node*);// Find an equivalent version in hash table
    Node  *hash_find_insert(Node*);// If not in table insert else return found node
    void   hash_insert(Node*);    // Insert into hash table
    bool   hash_delete(const Node*);// Replace with _sentinel in hash table
    void   check_grow() {
      _inserts++;
      if( _inserts == _insert_limit ) { grow(); }
      assert( _inserts <= _insert_limit, "hash table overflow");
      assert( _inserts < _max, "hash table overflow" );
    }
    static uint round_up(uint);   // Round up to nearest power of 2
    void   grow();                // Grow _table to next power of 2 and rehash
    // Return 75% of _max, rounded up.
    uint   insert_limit() const { return _max - (_max>>2); }
  
    void   clear();               // Set all entries to NULL, keep storage.
    // Size of hash table
    uint   size()         const { return _max; }
    // Return Node* at index in table
    Node  *at(uint table_index) {
      assert(table_index < _max, "Must be within table");
      return _table[table_index];
    }
  
    void   remove_useless_nodes(VectorSet &useful); // replace with sentinel
    void   replace_with(NodeHash* nh);
    void   check_no_speculative_types(); // Check no speculative part for type nodes in table
  
    Node  *sentinel() { return _sentinel; }
  
  #ifndef PRODUCT
    Node  *find_index(uint idx);  // For debugging
    void   dump();                // For debugging, dump statistics
    uint   _grows;                // For debugging, count of table grow()s
    uint   _look_probes;          // For debugging, count of hash probes
    uint   _lookup_hits;          // For debugging, count of hash_finds
    uint   _lookup_misses;        // For debugging, count of hash_finds
    uint   _insert_probes;        // For debugging, count of hash probes
    uint   _delete_probes;        // For debugging, count of hash probes for deletes
    uint   _delete_hits;          // For debugging, count of hash probes for deletes
    uint   _delete_misses;        // For debugging, count of hash probes for deletes
    uint   _total_inserts;        // For debugging, total inserts into hash table
    uint   _total_insert_probes;  // For debugging, total probes while inserting
  #endif
  };
  
  
  //-----------------------------------------------------------------------------
  // Map dense integer indices to Types.  Uses classic doubling-array trick.
  // Abstractly provides an infinite array of Type*'s, initialized to NULL.
  // Note that the constructor just zeros things, and since I use Arena
  // allocation I do not need a destructor to reclaim storage.
  // Despite the general name, this class is customized for use by PhaseTransform.
  class Type_Array : public StackObj {
    Arena *_a;                    // Arena to allocate in
    uint   _max;
    const Type **_types;
    void grow( uint i );          // Grow array node to fit
    const Type *operator[] ( uint i ) const // Lookup, or NULL for not mapped
    { return (i<_max) ? _types[i] : (Type*)NULL; }
    friend class PhaseTransform;
  public:
    Type_Array(Arena *a) : _a(a), _max(0), _types(0) {}
    Type_Array(Type_Array *ta) : _a(ta->_a), _max(ta->_max), _types(ta->_types) { }
    const Type *fast_lookup(uint i) const{assert(i<_max,"oob");return _types[i];}
    // Extend the mapping: index i maps to Type *n.
    void map( uint i, const Type *n ) { if( i>=_max ) grow(i); _types[i] = n; }
    uint Size() const { return _max; }
  #ifndef PRODUCT
    void dump() const;
  #endif
  };
  
  
  //------------------------------PhaseRemoveUseless-----------------------------
  // Remove useless nodes from GVN hash-table, worklist, and graph
  class PhaseRemoveUseless : public Phase {
  protected:
    Unique_Node_List _useful;   // Nodes reachable from root
                                // list is allocated from current resource area
  public:
    PhaseRemoveUseless(PhaseGVN *gvn, Unique_Node_List *worklist, PhaseNumber phase_num = Remove_Useless);
  
    Unique_Node_List *get_useful() { return &_useful; }
  };
  
  //------------------------------PhaseRenumber----------------------------------
  // Phase that first performs a PhaseRemoveUseless, then it renumbers compiler
  // structures accordingly.
  class PhaseRenumberLive : public PhaseRemoveUseless {
  public:
    PhaseRenumberLive(PhaseGVN* gvn,
                      Unique_Node_List* worklist, Unique_Node_List* new_worklist,
                      PhaseNumber phase_num = Remove_Useless_And_Renumber_Live);
  };
  
  
  //------------------------------PhaseTransform---------------------------------
  // Phases that analyze, then transform.  Constructing the Phase object does any
  // global or slow analysis.  The results are cached later for a fast
  // transformation pass.  When the Phase object is deleted the cached analysis
  // results are deleted.
  class PhaseTransform : public Phase {
  protected:
    Arena*     _arena;
    Node_List  _nodes;           // Map old node indices to new nodes.
    Type_Array _types;           // Map old node indices to Types.
  
    // ConNode caches:
    enum { _icon_min = -1 * HeapWordSize,
           _icon_max = 16 * HeapWordSize,
           _lcon_min = _icon_min,
           _lcon_max = _icon_max,
           _zcon_max = (uint)T_CONFLICT
    };
    ConINode* _icons[_icon_max - _icon_min + 1];   // cached jint constant nodes
    ConLNode* _lcons[_lcon_max - _lcon_min + 1];   // cached jlong constant nodes
    ConNode*  _zcons[_zcon_max + 1];               // cached is_zero_type nodes
    void init_con_caches();
  
    // Support both int and long caches because either might be an intptr_t,
    // so they show up frequently in address computations.
  
  public:
    PhaseTransform( PhaseNumber pnum );
    PhaseTransform( Arena *arena, PhaseNumber pnum );
    PhaseTransform( PhaseTransform *phase, PhaseNumber pnum );
  
    Arena*      arena()   { return _arena; }
    Type_Array& types()   { return _types; }
    void replace_types(Type_Array new_types) {
      _types = new_types;
    }
    // _nodes is used in varying ways by subclasses, which define local accessors
    uint nodes_size() {
      return _nodes.size();
    }
  
  public:
    // Get a previously recorded type for the node n.
    // This type must already have been recorded.
    // If you want the type of a very new (untransformed) node,
    // you must use type_or_null, and test the result for NULL.
    const Type* type(const Node* n) const {
      assert(_pnum != Ideal_Loop, "should not be used from PhaseIdealLoop");
      assert(n != NULL, "must not be null");
      const Type* t = _types.fast_lookup(n->_idx);
      assert(t != NULL, "must set before get");
      return t;
    }
    // Get a previously recorded type for the node n,
    // or else return NULL if there is none.
    const Type* type_or_null(const Node* n) const {
      assert(_pnum != Ideal_Loop, "should not be used from PhaseIdealLoop");
      return _types.fast_lookup(n->_idx);
    }
    // Record a type for a node.
    void    set_type(const Node* n, const Type *t) {
      assert(t != NULL, "type must not be null");
      _types.map(n->_idx, t);
    }
    // Record an initial type for a node, the node's bottom type.
    void    set_type_bottom(const Node* n) {
      // Use this for initialization when bottom_type() (or better) is not handy.
      // Usually the initialization shoudl be to n->Value(this) instead,
      // or a hand-optimized value like Type::MEMORY or Type::CONTROL.
      assert(_types[n->_idx] == NULL, "must set the initial type just once");
      _types.map(n->_idx, n->bottom_type());
    }
    // Make sure the types array is big enough to record a size for the node n.
    // (In product builds, we never want to do range checks on the types array!)
    void ensure_type_or_null(const Node* n) {
      if (n->_idx >= _types.Size())
        _types.map(n->_idx, NULL);   // Grow the types array as needed.
    }
  
    // Utility functions:
    const TypeInt*  find_int_type( Node* n);
    const TypeLong* find_long_type(Node* n);
    jint  find_int_con( Node* n, jint  value_if_unknown) {
      const TypeInt* t = find_int_type(n);
      return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
    }
    jlong find_long_con(Node* n, jlong value_if_unknown) {
      const TypeLong* t = find_long_type(n);
      return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
    }
  
    // Make an idealized constant, i.e., one of ConINode, ConPNode, ConFNode, etc.
    // Same as transform(ConNode::make(t)).
    ConNode* makecon(const Type* t);
    virtual ConNode* uncached_makecon(const Type* t)  // override in PhaseValues
    { ShouldNotCallThis(); return NULL; }
  
    // Fast int or long constant.  Same as TypeInt::make(i) or TypeLong::make(l).
    ConINode* intcon(jint i);
    ConLNode* longcon(jlong l);
  
    // Fast zero or null constant.  Same as makecon(Type::get_zero_type(bt)).
    ConNode* zerocon(BasicType bt);
  
    // Return a node which computes the same function as this node, but
    // in a faster or cheaper fashion.
    virtual Node *transform( Node *n ) = 0;
  
    // Return whether two Nodes are equivalent.
    // Must not be recursive, since the recursive version is built from this.
    // For pessimistic optimizations this is simply pointer equivalence.
    bool eqv(const Node* n1, const Node* n2) const { return n1 == n2; }
  
    // For pessimistic passes, the return type must monotonically narrow.
    // For optimistic  passes, the return type must monotonically widen.
    // It is possible to get into a "death march" in either type of pass,
    // where the types are continually moving but it will take 2**31 or
    // more steps to converge.  This doesn't happen on most normal loops.
    //
    // Here is an example of a deadly loop for an optimistic pass, along
    // with a partial trace of inferred types:
    //    x = phi(0,x'); L: x' = x+1; if (x' >= 0) goto L;
    //    0                 1                join([0..max], 1)
    //    [0..1]            [1..2]           join([0..max], [1..2])
    //    [0..2]            [1..3]           join([0..max], [1..3])
    //      ... ... ...
    //    [0..max]          [min]u[1..max]   join([0..max], [min..max])
    //    [0..max] ==> fixpoint
    // We would have proven, the hard way, that the iteration space is all
    // non-negative ints, with the loop terminating due to 32-bit overflow.
    //
    // Here is the corresponding example for a pessimistic pass:
    //    x = phi(0,x'); L: x' = x-1; if (x' >= 0) goto L;
    //    int               int              join([0..max], int)
    //    [0..max]          [-1..max-1]      join([0..max], [-1..max-1])
    //    [0..max-1]        [-1..max-2]      join([0..max], [-1..max-2])
    //      ... ... ...
    //    [0..1]            [-1..0]          join([0..max], [-1..0])
    //    0                 -1               join([0..max], -1)
    //    0 == fixpoint
    // We would have proven, the hard way, that the iteration space is {0}.
    // (Usually, other optimizations will make the "if (x >= 0)" fold up
    // before we get into trouble.  But not always.)
    //
    // It's a pleasant thing to observe that the pessimistic pass
    // will make short work of the optimistic pass's deadly loop,
    // and vice versa.  That is a good example of the complementary
    // purposes of the CCP (optimistic) vs. GVN (pessimistic) phases.
    //
    // In any case, only widen or narrow a few times before going to the
    // correct flavor of top or bottom.
    //
    // This call only needs to be made once as the data flows around any
    // given cycle.  We do it at Phis, and nowhere else.
    // The types presented are the new type of a phi (computed by PhiNode::Value)
    // and the previously computed type, last time the phi was visited.
    //
    // The third argument is upper limit for the saturated value,
    // if the phase wishes to widen the new_type.
    // If the phase is narrowing, the old type provides a lower limit.
    // Caller guarantees that old_type and new_type are no higher than limit_type.
    virtual const Type* saturate(const Type* new_type, const Type* old_type,
                                 const Type* limit_type) const
    { ShouldNotCallThis(); return NULL; }
  
    // Delayed node rehash if this is an IGVN phase
    virtual void igvn_rehash_node_delayed(Node* n) {}
  
    // true if CFG node d dominates CFG node n
    virtual bool is_dominator(Node *d, Node *n) { fatal("unimplemented for this pass"); return false; };
  
  #ifndef PRODUCT
    void dump_old2new_map() const;
    void dump_new( uint new_lidx ) const;
    void dump_types() const;
    void dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl = true);
    void dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited);
  
    uint   _count_progress;       // For profiling, count transforms that make progress
    void   set_progress()        { ++_count_progress; assert( allow_progress(),"No progress allowed during verification"); }
    void   clear_progress()      { _count_progress = 0; }
    uint   made_progress() const { return _count_progress; }
  
    uint   _count_transforms;     // For profiling, count transforms performed
    void   set_transforms()      { ++_count_transforms; }
    void   clear_transforms()    { _count_transforms = 0; }
    uint   made_transforms() const{ return _count_transforms; }
  
    bool   _allow_progress;      // progress not allowed during verification pass
    void   set_allow_progress(bool allow) { _allow_progress = allow; }
    bool   allow_progress()               { return _allow_progress; }
  #endif
  };
  
  //------------------------------PhaseValues------------------------------------
  // Phase infrastructure to support values
  class PhaseValues : public PhaseTransform {
  protected:
    NodeHash  _table;             // Hash table for value-numbering
  
  public:
    PhaseValues( Arena *arena, uint est_max_size );
    PhaseValues( PhaseValues *pt );
    PhaseValues( PhaseValues *ptv, const char *dummy );
    NOT_PRODUCT( ~PhaseValues(); )
    virtual PhaseIterGVN *is_IterGVN() { return 0; }
  
    // Some Ideal and other transforms delete --> modify --> insert values
    bool   hash_delete(Node *n)     { return _table.hash_delete(n); }
    void   hash_insert(Node *n)     { _table.hash_insert(n); }
    Node  *hash_find_insert(Node *n){ return _table.hash_find_insert(n); }
    Node  *hash_find(const Node *n) { return _table.hash_find(n); }
  
    // Used after parsing to eliminate values that are no longer in program
    void   remove_useless_nodes(VectorSet &useful) {
      _table.remove_useless_nodes(useful);
      // this may invalidate cached cons so reset the cache
      init_con_caches();
    }
  
    virtual ConNode* uncached_makecon(const Type* t);  // override from PhaseTransform
  
    virtual const Type* saturate(const Type* new_type, const Type* old_type,
                                 const Type* limit_type) const
    { return new_type; }
  
  #ifndef PRODUCT
    uint   _count_new_values;     // For profiling, count new values produced
    void    inc_new_values()        { ++_count_new_values; }
    void    clear_new_values()      { _count_new_values = 0; }
    uint    made_new_values() const { return _count_new_values; }
  #endif
  };
  
  
  //------------------------------PhaseGVN---------------------------------------
  // Phase for performing local, pessimistic GVN-style optimizations.
  class PhaseGVN : public PhaseValues {
  protected:
    bool is_dominator_helper(Node *d, Node *n, bool linear_only);
  
  public:
    PhaseGVN( Arena *arena, uint est_max_size ) : PhaseValues( arena, est_max_size ) {}
    PhaseGVN( PhaseGVN *gvn ) : PhaseValues( gvn ) {}
    PhaseGVN( PhaseGVN *gvn, const char *dummy ) : PhaseValues( gvn, dummy ) {}
  
    // Return a node which computes the same function as this node, but
    // in a faster or cheaper fashion.
    Node  *transform( Node *n );
    Node  *transform_no_reclaim( Node *n );
    virtual void record_for_igvn(Node *n) {
      C->record_for_igvn(n);
    }
  
    void replace_with(PhaseGVN* gvn) {
      _table.replace_with(&gvn->_table);
      _types = gvn->_types;
    }
  
    bool is_dominator(Node *d, Node *n) { return is_dominator_helper(d, n, true); }
  
    // Check for a simple dead loop when a data node references itself.
    DEBUG_ONLY(void dead_loop_check(Node *n);)
  };
  
  //------------------------------PhaseIterGVN-----------------------------------
  // Phase for iteratively performing local, pessimistic GVN-style optimizations.
  // and ideal transformations on the graph.
  class PhaseIterGVN : public PhaseGVN {
  private:
    bool _delay_transform;  // When true simply register the node when calling transform
                            // instead of actually optimizing it
  
    // Idealize old Node 'n' with respect to its inputs and its value
    virtual Node *transform_old( Node *a_node );
  
    // Subsume users of node 'old' into node 'nn'
    void subsume_node( Node *old, Node *nn );
  
    Node_Stack _stack;      // Stack used to avoid recursion
  
  protected:
  
    // Warm up hash table, type table and initial worklist
    void init_worklist( Node *a_root );
  
    virtual const Type* saturate(const Type* new_type, const Type* old_type,
                                 const Type* limit_type) const;
    // Usually returns new_type.  Returns old_type if new_type is only a slight
    // improvement, such that it would take many (>>10) steps to reach 2**32.
  
  public:
    PhaseIterGVN( PhaseIterGVN *igvn ); // Used by CCP constructor
    PhaseIterGVN( PhaseGVN *gvn ); // Used after Parser
    PhaseIterGVN( PhaseIterGVN *igvn, const char *dummy ); // Used after +VerifyOpto
  
    // Idealize new Node 'n' with respect to its inputs and its value
    virtual Node *transform( Node *a_node );
    virtual void record_for_igvn(Node *n) { }
  
    virtual PhaseIterGVN *is_IterGVN() { return this; }
  
    Unique_Node_List _worklist;       // Iterative worklist
  
    // Given def-use info and an initial worklist, apply Node::Ideal,
    // Node::Value, Node::Identity, hash-based value numbering, Node::Ideal_DU
    // and dominator info to a fixed point.
    void optimize();
  
  #ifndef PRODUCT
    void trace_PhaseIterGVN(Node* n, Node* nn, const Type* old_type);
    void init_verifyPhaseIterGVN();
    void verify_PhaseIterGVN();
  #endif
  
  #ifdef ASSERT
    void dump_infinite_loop_info(Node* n);
    void trace_PhaseIterGVN_verbose(Node* n, int num_processed);
  #endif
  
    // Register a new node with the iter GVN pass without transforming it.
    // Used when we need to restructure a Region/Phi area and all the Regions
    // and Phis need to complete this one big transform before any other
    // transforms can be triggered on the region.
    // Optional 'orig' is an earlier version of this node.
    // It is significant only for debugging and profiling.
    Node* register_new_node_with_optimizer(Node* n, Node* orig = NULL);
  
    // Kill a globally dead Node.  All uses are also globally dead and are
    // aggressively trimmed.
    void remove_globally_dead_node( Node *dead );
  
    // Kill all inputs to a dead node, recursively making more dead nodes.
    // The Node must be dead locally, i.e., have no uses.
    void remove_dead_node( Node *dead ) {
      assert(dead->outcnt() == 0 && !dead->is_top(), "node must be dead");
      remove_globally_dead_node(dead);
    }
  
    // Add users of 'n' to worklist
    void add_users_to_worklist0( Node *n );
    void add_users_to_worklist ( Node *n );
  
    // Replace old node with new one.
    void replace_node( Node *old, Node *nn ) {
      add_users_to_worklist(old);
      hash_delete(old); // Yank from hash before hacking edges
      subsume_node(old, nn);
    }
  
    // Delayed node rehash: remove a node from the hash table and rehash it during
    // next optimizing pass
    void rehash_node_delayed(Node* n) {
      hash_delete(n);
      _worklist.push(n);
    }
  
    void igvn_rehash_node_delayed(Node* n) {
      rehash_node_delayed(n);
    }
  
    // Replace ith edge of "n" with "in"
    void replace_input_of(Node* n, int i, Node* in) {
      rehash_node_delayed(n);
      n->set_req(i, in);
    }
  
    // Delete ith edge of "n"
    void delete_input_of(Node* n, int i) {
      rehash_node_delayed(n);
      n->del_req(i);
    }
  
    bool delay_transform() const { return _delay_transform; }
  
    void set_delay_transform(bool delay) {
      _delay_transform = delay;
    }
  
    // Clone loop predicates. Defined in loopTransform.cpp.
    Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
    // Create a new if below new_entry for the predicate to be cloned
    ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
                                          Deoptimization::DeoptReason reason,
                                          int opcode);
  
    void remove_speculative_types();
    void check_no_speculative_types() {
      _table.check_no_speculative_types();
    }
  
    bool is_dominator(Node *d, Node *n) { return is_dominator_helper(d, n, false); }
  
  #ifndef PRODUCT
  protected:
    // Sub-quadratic implementation of VerifyIterativeGVN.
    julong _verify_counter;
    julong _verify_full_passes;
    enum { _verify_window_size = 30 };
    Node* _verify_window[_verify_window_size];
    void verify_step(Node* n);
  #endif
  };
  
  //------------------------------PhaseCCP---------------------------------------
  // Phase for performing global Conditional Constant Propagation.
  // Should be replaced with combined CCP & GVN someday.
  class PhaseCCP : public PhaseIterGVN {
    // Non-recursive.  Use analysis to transform single Node.
    virtual Node *transform_once( Node *n );
  
  public:
    PhaseCCP( PhaseIterGVN *igvn ); // Compute conditional constants
    NOT_PRODUCT( ~PhaseCCP(); )
  
    // Worklist algorithm identifies constants
    void analyze();
    // Recursive traversal of program.  Used analysis to modify program.
    virtual Node *transform( Node *n );
    // Do any transformation after analysis
    void          do_transform();
  
    virtual const Type* saturate(const Type* new_type, const Type* old_type,
                                 const Type* limit_type) const;
    // Returns new_type->widen(old_type), which increments the widen bits until
    // giving up with TypeInt::INT or TypeLong::LONG.
    // Result is clipped to limit_type if necessary.
  
  #ifndef PRODUCT
    static uint _total_invokes;    // For profiling, count invocations
    void    inc_invokes()          { ++PhaseCCP::_total_invokes; }
  
    static uint _total_constants;  // For profiling, count constants found
    uint   _count_constants;
    void    clear_constants()      { _count_constants = 0; }
    void    inc_constants()        { ++_count_constants; }
    uint    count_constants() const { return _count_constants; }
  
    static void print_statistics();
  #endif
  };
  
  
  //------------------------------PhasePeephole----------------------------------
  // Phase for performing peephole optimizations on register allocated basic blocks.
  class PhasePeephole : public PhaseTransform {
    PhaseRegAlloc *_regalloc;
    PhaseCFG     &_cfg;
    // Recursive traversal of program.  Pure function is unused in this phase
    virtual Node *transform( Node *n );
  
  public:
    PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg );
    NOT_PRODUCT( ~PhasePeephole(); )
  
    // Do any transformation after analysis
    void          do_transform();
  
  #ifndef PRODUCT
    static uint _total_peepholes;  // For profiling, count peephole rules applied
    uint   _count_peepholes;
    void    clear_peepholes()      { _count_peepholes = 0; }
    void    inc_peepholes()        { ++_count_peepholes; }
    uint    count_peepholes() const { return _count_peepholes; }
  
    static void print_statistics();
  #endif
  };
  
  #endif // SHARE_VM_OPTO_PHASEX_HPP
  