/*

 * Copyright (c) 2005, 2012, 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

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#ifndef SHARE_VM_OPTO_ESCAPE_HPP

#define SHARE_VM_OPTO_ESCAPE_HPP

#include "opto/addnode.hpp"

#include "opto/node.hpp"

#include "utilities/growableArray.hpp"

//

// Adaptation for C2 of the escape analysis algorithm described in:

//

// [Choi99] Jong-Deok Shoi, Manish Gupta, Mauricio Seffano,

//          Vugranam C. Sreedhar, Sam Midkiff,

//          "Escape Analysis for Java", Procedings of ACM SIGPLAN

//          OOPSLA  Conference, November 1, 1999

//

// The flow-insensitive analysis described in the paper has been implemented.

//

// The analysis requires construction of a "connection graph" (CG) for

// the method being analyzed.  The nodes of the connection graph are:

//

//     -  Java objects (JO)

//     -  Local variables (LV)

//     -  Fields of an object (OF),  these also include array elements

//

// The CG contains 3 types of edges:

//

//   -  PointsTo  (-P>)    {LV, OF} to JO

//   -  Deferred  (-D>)    from {LV, OF} to {LV, OF}

//   -  Field     (-F>)    from JO to OF

//

// The following  utility functions is used by the algorithm:

//

//   PointsTo(n) - n is any CG node, it returns the set of JO that n could

//                 point to.

//

// The algorithm describes how to construct the connection graph

// in the following 4 cases:

//

//          Case                  Edges Created

//

// (1)   p   = new T()              LV -P> JO

// (2)   p   = q                    LV -D> LV

// (3)   p.f = q                    JO -F> OF,  OF -D> LV

// (4)   p   = q.f                  JO -F> OF,  LV -D> OF

//

// In all these cases, p and q are local variables.  For static field

// references, we can construct a local variable containing a reference

// to the static memory.

//

// C2 does not have local variables.  However for the purposes of constructing

// the connection graph, the following IR nodes are treated as local variables:

//     Phi    (pointer values)

//     LoadP, LoadN

//     Proj#5 (value returned from callnodes including allocations)

//     CheckCastPP, CastPP

//

// The LoadP, Proj and CheckCastPP behave like variables assigned to only once.

// Only a Phi can have multiple assignments.  Each input to a Phi is treated

// as an assignment to it.

//

// The following node types are JavaObject:

//

//     phantom_object (general globally escaped object)

//     Allocate

//     AllocateArray

//     Parm  (for incoming arguments)

//     CastX2P ("unsafe" operations)

//     CreateEx

//     ConP

//     LoadKlass

//     ThreadLocal

//     CallStaticJava (which returns Object)

//

// AddP nodes are fields.

//

// After building the graph, a pass is made over the nodes, deleting deferred

// nodes and copying the edges from the target of the deferred edge to the

// source.  This results in a graph with no deferred edges, only:

//

//    LV -P> JO

//    OF -P> JO (the object whose oop is stored in the field)

//    JO -F> OF

//

// Then, for each node which is GlobalEscape, anything it could point to

// is marked GlobalEscape.  Finally, for any node marked ArgEscape, anything

// it could point to is marked ArgEscape.

//

class  Compile;

class  Node;

class  CallNode;

class  PhiNode;

class  PhaseTransform;

class  PointsToNode;

class  Type;

class  TypePtr;

class  VectorSet;

class JavaObjectNode;

class LocalVarNode;

class FieldNode;

class ArraycopyNode;

// ConnectionGraph nodes

class PointsToNode : public ResourceObj {

  GrowableArray<PointsToNode*> _edges; // List of nodes this node points to

  GrowableArray<PointsToNode*> _uses;  // List of nodes which point to this node

  const u1           _type;  // NodeType

  u1                _flags;  // NodeFlags

  u1               _escape;  // EscapeState of object

  u1        _fields_escape;  // EscapeState of object's fields

  Node* const        _node;  // Ideal node corresponding to this PointsTo node.

  const int           _idx;  // Cached ideal node's _idx

public:

  typedef enum {

    UnknownType = 0,

    JavaObject  = 1,

    LocalVar    = 2,

    Field       = 3,

    Arraycopy   = 4

  } NodeType;

  typedef enum {

    UnknownEscape = 0,

    NoEscape      = 1, // An object does not escape method or thread and it is

                       // not passed to call. It could be replaced with scalar.

    ArgEscape     = 2, // An object does not escape method or thread but it is

                       // passed as argument to call or referenced by argument

                       // and it does not escape during call.

    GlobalEscape  = 3  // An object escapes the method or thread.

  } EscapeState;

  typedef enum {

    ScalarReplaceable = 1,  // Not escaped object could be replaced with scalar

    PointsToUnknown   = 2,  // Has edge to phantom_object

    ArraycopySrc      = 4,  // Has edge from Arraycopy node

    ArraycopyDst      = 8   // Has edge to Arraycopy node

  } NodeFlags;

  PointsToNode(Compile *C, Node* n, EscapeState es, NodeType type):

    _edges(C->comp_arena(), 2, 0, NULL),

    _uses (C->comp_arena(), 2, 0, NULL),

    _node(n),

    _idx(n->_idx),

    _type((u1)type),

    _escape((u1)es),

    _fields_escape((u1)es),

    _flags(ScalarReplaceable) {

    assert(n != NULL && es != UnknownEscape, "sanity");

  }

  Node* ideal_node()   const { return _node; }

  int          idx()   const { return _idx; }

  bool is_JavaObject() const { return _type == (u1)JavaObject; }

  bool is_LocalVar()   const { return _type == (u1)LocalVar; }

  bool is_Field()      const { return _type == (u1)Field; }

  bool is_Arraycopy()  const { return _type == (u1)Arraycopy; }

  JavaObjectNode* as_JavaObject() { assert(is_JavaObject(),""); return (JavaObjectNode*)this; }

  LocalVarNode*   as_LocalVar()   { assert(is_LocalVar(),"");   return (LocalVarNode*)this; }

  FieldNode*      as_Field()      { assert(is_Field(),"");      return (FieldNode*)this; }

  ArraycopyNode*  as_Arraycopy()  { assert(is_Arraycopy(),"");  return (ArraycopyNode*)this; }

  EscapeState escape_state() const { return (EscapeState)_escape; }

  void    set_escape_state(EscapeState state) { _escape = (u1)state; }

  EscapeState fields_escape_state() const { return (EscapeState)_fields_escape; }

  void    set_fields_escape_state(EscapeState state) { _fields_escape = (u1)state; }

  bool     has_unknown_ptr() const { return (_flags & PointsToUnknown) != 0; }

  void set_has_unknown_ptr()       { _flags |= PointsToUnknown; }

  bool     arraycopy_src() const { return (_flags & ArraycopySrc) != 0; }

  void set_arraycopy_src()       { _flags |= ArraycopySrc; }

  bool     arraycopy_dst() const { return (_flags & ArraycopyDst) != 0; }

  void set_arraycopy_dst()       { _flags |= ArraycopyDst; }

  bool     scalar_replaceable() const { return (_flags & ScalarReplaceable) != 0;}

  void set_scalar_replaceable(bool v) {

    if (v)

      _flags |= ScalarReplaceable;

    else

      _flags &= ~ScalarReplaceable;

  }

  int edge_count()              const { return _edges.length(); }

  PointsToNode* edge(int e)     const { return _edges.at(e); }

  bool add_edge(PointsToNode* edge)    { return _edges.append_if_missing(edge); }

  int use_count()             const { return _uses.length(); }

  PointsToNode* use(int e)    const { return _uses.at(e); }

  bool add_use(PointsToNode* use)    { return _uses.append_if_missing(use); }

  // Mark base edge use to distinguish from stored value edge.

  bool add_base_use(FieldNode* use) { return _uses.append_if_missing((PointsToNode*)((intptr_t)use + 1)); }

  static bool is_base_use(PointsToNode* use) { return (((intptr_t)use) & 1); }

  static PointsToNode* get_use_node(PointsToNode* use) { return (PointsToNode*)(((intptr_t)use) & ~1); }

  // Return true if this node points to specified node or nodes it points to.

  bool points_to(JavaObjectNode* ptn) const;

  // Return true if this node points only to non-escaping allocations.

  bool non_escaping_allocation();

  // Return true if one node points to an other.

  bool meet(PointsToNode* ptn);

#ifndef PRODUCT

  NodeType node_type() const { return (NodeType)_type;}

  void dump(bool print_state=true) const;

#endif

};

class LocalVarNode: public PointsToNode {

public:

  LocalVarNode(Compile *C, Node* n, EscapeState es):

    PointsToNode(C, n, es, LocalVar) {}

};

class JavaObjectNode: public PointsToNode {

public:

  JavaObjectNode(Compile *C, Node* n, EscapeState es):

    PointsToNode(C, n, es, JavaObject) {

      if (es > NoEscape)

        set_scalar_replaceable(false);

    }

};

class FieldNode: public PointsToNode {

  GrowableArray<PointsToNode*> _bases; // List of JavaObject nodes which point to this node

  const int   _offset; // Field's offset.

  const bool  _is_oop; // Field points to object

        bool  _has_unknown_base; // Has phantom_object base

public:

  FieldNode(Compile *C, Node* n, EscapeState es, int offs, bool is_oop):

    PointsToNode(C, n, es, Field),

    _offset(offs), _is_oop(is_oop),

    _has_unknown_base(false) {}

  int      offset()              const { return _offset;}

  bool     is_oop()              const { return _is_oop;}

  bool     has_unknown_base()    const { return _has_unknown_base; }

  void set_has_unknown_base()          { _has_unknown_base = true; }

  int base_count()              const { return _bases.length(); }

  PointsToNode* base(int e)     const { return _bases.at(e); }

  bool add_base(PointsToNode* base)    { return _bases.append_if_missing(base); }

#ifdef ASSERT

  // Return true if bases points to this java object.

  bool has_base(JavaObjectNode* ptn) const;

#endif

};

class ArraycopyNode: public PointsToNode {

public:

  ArraycopyNode(Compile *C, Node* n, EscapeState es):

    PointsToNode(C, n, es, Arraycopy) {}

};

// Iterators for PointsTo node's edges:

//   for (EdgeIterator i(n); i.has_next(); i.next()) {

//     PointsToNode* u = i.get();

class PointsToIterator: public StackObj {

protected:

  const PointsToNode* node;

  const int cnt;

  int i;

public:

  inline PointsToIterator(const PointsToNode* n, int cnt) : node(n), cnt(cnt), i(0) { }

  inline bool has_next() const { return i < cnt; }

  inline void next() { i++; }

  PointsToNode* get() const { ShouldNotCallThis(); return NULL; }

};

class EdgeIterator: public PointsToIterator {

public:

  inline EdgeIterator(const PointsToNode* n) : PointsToIterator(n, n->edge_count()) { }

  inline PointsToNode* get() const { return node->edge(i); }

};

class UseIterator: public PointsToIterator {

public:

  inline UseIterator(const PointsToNode* n) : PointsToIterator(n, n->use_count()) { }

  inline PointsToNode* get() const { return node->use(i); }

};

class BaseIterator: public PointsToIterator {

public:

  inline BaseIterator(const FieldNode* n) : PointsToIterator(n, n->base_count()) { }

  inline PointsToNode* get() const { return ((PointsToNode*)node)->as_Field()->base(i); }

};

class ConnectionGraph: public ResourceObj {

private:

  GrowableArray<PointsToNode*>  _nodes; // Map from ideal nodes to

                                        // ConnectionGraph nodes.

  GrowableArray<PointsToNode*>  _worklist; // Nodes to be processed

  bool            _collecting; // Indicates whether escape information

                               // is still being collected. If false,

                               // no new nodes will be processed.

  bool               _verify;  // verify graph

  JavaObjectNode* phantom_obj; // Unknown object

  JavaObjectNode*    null_obj;

  Node*             _pcmp_neq; // ConI(#CC_GT)

  Node*              _pcmp_eq; // ConI(#CC_EQ)

  Compile*           _compile; // Compile object for current compilation

  PhaseIterGVN*         _igvn; // Value numbering

  Unique_Node_List ideal_nodes; // Used by CG construction and types splitting.

  // Address of an element in _nodes.  Used when the element is to be modified

  PointsToNode* ptnode_adr(int idx) const {

    // There should be no new ideal nodes during ConnectionGraph build,

    // growableArray::at() will throw assert otherwise.

    return _nodes.at(idx);

  }

  uint nodes_size() const { return _nodes.length(); }

  // Add nodes to ConnectionGraph.

  void add_local_var(Node* n, PointsToNode::EscapeState es);

  void add_java_object(Node* n, PointsToNode::EscapeState es);

  void add_field(Node* n, PointsToNode::EscapeState es, int offset);

  void add_arraycopy(Node* n, PointsToNode::EscapeState es, PointsToNode* src, PointsToNode* dst);

  // Compute the escape state for arguments to a call.

  void process_call_arguments(CallNode *call);

  // Add PointsToNode node corresponding to a call

  void add_call_node(CallNode* call);

  // Map ideal node to existing PointsTo node (usually phantom_object).

  void map_ideal_node(Node *n, PointsToNode* ptn) {

    assert(ptn != NULL, "only existing PointsTo node");

    _nodes.at_put(n->_idx, ptn);

  }

  // Create PointsToNode node and add it to Connection Graph.

  void add_node_to_connection_graph(Node *n, Unique_Node_List *delayed_worklist);

  // Add final simple edges to graph.

  void add_final_edges(Node *n);

  // Finish Graph construction.

  bool complete_connection_graph(GrowableArray<PointsToNode*>&   ptnodes_worklist,

                                 GrowableArray<JavaObjectNode*>& non_escaped_worklist,

                                 GrowableArray<JavaObjectNode*>& java_objects_worklist,

                                 GrowableArray<FieldNode*>&      oop_fields_worklist);

#ifdef ASSERT

  void verify_connection_graph(GrowableArray<PointsToNode*>&   ptnodes_worklist,

                               GrowableArray<JavaObjectNode*>& non_escaped_worklist,

                               GrowableArray<JavaObjectNode*>& java_objects_worklist,

                               GrowableArray<Node*>& addp_worklist);

#endif

  // Add all references to this JavaObject node.

  int add_java_object_edges(JavaObjectNode* jobj, bool populate_worklist);

  // Put node on worklist if it is (or was) not there.

  void add_to_worklist(PointsToNode* pt) {

    _worklist.push(pt);

    return;

  }

  // Put on worklist all uses of this node.

  void add_uses_to_worklist(PointsToNode* pt) {

    for (UseIterator i(pt); i.has_next(); i.next())

      _worklist.push(i.get());

  }

  // Put on worklist all field's uses and related field nodes.

  void add_field_uses_to_worklist(FieldNode* field);

  // Put on worklist all related field nodes.

  void add_fields_to_worklist(FieldNode* field, PointsToNode* base);

  // Find fields which have unknown value.

  int find_field_value(FieldNode* field);

  // Find fields initializing values for allocations.

  int find_init_values(JavaObjectNode* ptn, PointsToNode* init_val, PhaseTransform* phase);

  // Set the escape state of an object and its fields.

  void set_escape_state(PointsToNode* ptn, PointsToNode::EscapeState esc) {

    // Don't change non-escaping state of NULL pointer.

    if (ptn != null_obj) {

      if (ptn->escape_state() < esc)

        ptn->set_escape_state(esc);

      if (ptn->fields_escape_state() < esc)

        ptn->set_fields_escape_state(esc);

    }

  }

  void set_fields_escape_state(PointsToNode* ptn, PointsToNode::EscapeState esc) {

    // Don't change non-escaping state of NULL pointer.

    if (ptn != null_obj) {

      if (ptn->fields_escape_state() < esc)

        ptn->set_fields_escape_state(esc);

    }

  }

  // Propagate GlobalEscape and ArgEscape escape states to all nodes

  // and check that we still have non-escaping java objects.

  bool find_non_escaped_objects(GrowableArray<PointsToNode*>& ptnodes_worklist,

                                GrowableArray<JavaObjectNode*>& non_escaped_worklist);

  // Adjust scalar_replaceable state after Connection Graph is built.

  void adjust_scalar_replaceable_state(JavaObjectNode* jobj);

  // Optimize ideal graph.

  void optimize_ideal_graph(GrowableArray<Node*>& ptr_cmp_worklist,

                            GrowableArray<Node*>& storestore_worklist);

  // Optimize objects compare.

  Node* optimize_ptr_compare(Node* n);

  // Returns unique corresponding java object or NULL.

  JavaObjectNode* unique_java_object(Node *n);

  // Add an edge of the specified type pointing to the specified target.

  bool add_edge(PointsToNode* from, PointsToNode* to) {

    assert(!from->is_Field() || from->as_Field()->is_oop(), "sanity");

    if (to == phantom_obj) {

      if (from->has_unknown_ptr()) {

        return false; // already points to phantom_obj

      }

      from->set_has_unknown_ptr();

    }

    bool is_new = from->add_edge(to);

    assert(to != phantom_obj || is_new, "sanity");

    if (is_new) { // New edge?

      assert(!_verify, "graph is incomplete");

      is_new = to->add_use(from);

      assert(is_new, "use should be also new");

    }

    return is_new;

  }

  // Add an edge from Field node to its base and back.

  bool add_base(FieldNode* from, PointsToNode* to) {

    assert(!to->is_Arraycopy(), "sanity");

    if (to == phantom_obj) {

      if (from->has_unknown_base()) {

        return false; // already has phantom_obj base

      }

      from->set_has_unknown_base();

    }

    bool is_new = from->add_base(to);

    assert(to != phantom_obj || is_new, "sanity");

    if (is_new) {      // New edge?

      assert(!_verify, "graph is incomplete");

      if (to == null_obj)

        return is_new; // Don't add fields to NULL pointer.

      if (to->is_JavaObject()) {

        is_new = to->add_edge(from);

      } else {

        is_new = to->add_base_use(from);

      }

      assert(is_new, "use should be also new");

    }