/*

 * Copyright 1997-2009 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.

 *

 */

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

  Node  *sentinel() { return _sentinel; }

#ifndef PRODUCT

  Node  *find_index(uint idx);  // For debugging

  void   dump();                // For debugging, dump statistics

#endif

  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

};

//-----------------------------------------------------------------------------

// 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 );

  Unique_Node_List *get_useful() { return &_useful; }

};

//------------------------------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_Array _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; }

  // _nodes is used in varying ways by subclasses, which define local accessors

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 {

    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 {

    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; }

  // Return whether two Nodes are equivalent, after stripping casting.

  bool eqv_uncast(const Node* n1, const Node* n2) const {

    return eqv(n1->uncast(), n2->uncast());

  }

  // 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; }

#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   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 {

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 );

  // 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 );

protected:

  // Idealize new Node 'n' with respect to its inputs and its value

  virtual Node *transform( Node *a_node );

  // 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

  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();

  // 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.   It is allowed to have uses which are

  // assumed dead and left 'in limbo'.

  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);

  }

  // Subsume users of node 'old' into node 'nn'

  // If no Def-Use info existed for 'nn' it will after call.

  void subsume_node( Node *old, Node *nn );

  // 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);

    subsume_node(old, nn);

  }

  bool delay_transform() const { return _delay_transform; }

  void set_delay_transform(bool delay) {

    _delay_transform = delay;

  }

#ifndef PRODUCT

protected:

  // Sub-quadratic implementation of VerifyIterativeGVN.

  unsigned long _verify_counter;

  unsigned long _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();