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 /*

  * Copyright 2005-2006 Sun Microsystems, Inc.  All Rights Reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * 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.

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  * 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.

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  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

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 //

 // 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

 //     Proj  (value returned from callnodes including allocations)

 //     CheckCastPP

 //

 // 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 note types are JavaObject:

 //

 //     top()

 //     Allocate

 //     AllocateArray

 //     Parm  (for incoming arguments)

 //     CreateEx

 //     ConP

 //     LoadKlass

 //

 // 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

 //    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  Type;

 class  TypePtr;

 class  VectorSet;

 class PointsToNode {

 friend class ConnectionGraph;

 public:

   typedef enum {

     UnknownType    = 0,

     JavaObject = 1,

     LocalVar   = 2,

     Field      = 3

   } NodeType;

   typedef enum {

     UnknownEscape = 0,

     NoEscape      = 1,

     ArgEscape     = 2,

     GlobalEscape  = 3

   } EscapeState;

   typedef enum {

     UnknownEdge   = 0,

     PointsToEdge  = 1,

     DeferredEdge  = 2,

     FieldEdge     = 3

   } EdgeType;

 private:

   enum {

     EdgeMask = 3,

     EdgeShift = 2,

     INITIAL_EDGE_COUNT = 4

   };

   NodeType             _type;

   EscapeState          _escape;

   GrowableArray<uint>* _edges;  // outgoing edges

   int                  _offset; // for fields

   bool       _unique_type;       // For allocated objects, this node may be a unique type

 public:

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

   int        _inputs_processed;  // the number of Phi inputs that have been processed so far

   bool       _hidden_alias;      // this node is an argument to a function which may return it

                                  // creating a hidden alias

   PointsToNode(): _offset(-1), _type(UnknownType), _escape(UnknownEscape), _edges(NULL), _node(NULL), _inputs_processed(0), _hidden_alias(false), _unique_type(true) {}

   EscapeState escape_state() const { return _escape; }

   NodeType node_type() const { return _type;}

   int offset() { return _offset;}

   void set_offset(int offs) { _offset = offs;}

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

   void set_node_type(NodeType ntype) {

     assert(_type == UnknownType || _type == ntype, "Can't change node type");

     _type = ntype;

   }

   // count of outgoing edges

   uint edge_count() const { return (_edges == NULL) ? 0 : _edges->length(); }

   // node index of target of outgoing edge "e"

   uint edge_target(uint e)  const;

   // type of outgoing edge "e"

   EdgeType edge_type(uint e)  const;

   // add a edge of the specified type pointing to the specified target

   void add_edge(uint targIdx, EdgeType et);

   // remove an edge of the specified type pointing to the specified target

   void remove_edge(uint targIdx, EdgeType et);

 #ifndef PRODUCT

   void dump() const;

 #endif

 };

 class ConnectionGraph: public ResourceObj {

 private:

   enum {

     INITIAL_NODE_COUNT = 100                    // initial size of _nodes array

   };

   GrowableArray<PointsToNode>* _nodes;          // connection graph nodes  Indexed by ideal

                                                 // node index

   Unique_Node_List             _deferred;       // Phi's to be processed after parsing

   VectorSet                    _processed;      // records which nodes have been processed

   bool                         _collecting;     // indicates whether escape information is

                                                 // still being collected.  If false, no new

                                                 // nodes will be processed

   uint                         _phantom_object; // index of globally escaping object that

                                                 // pointer values loaded from a field which

                                                 // has not been set are assumed to point to

   Compile *                    _compile;        // Compile object for current compilation

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

   PointsToNode *ptnode_adr(uint idx) {

     if ((uint)_nodes->length() <= idx) {

       // expand _nodes array

       PointsToNode dummy = _nodes->at_grow(idx);

     }

     return _nodes->adr_at(idx);

   }

   // offset of a field reference

   int type_to_offset(const Type *t);

   // compute the escape state for arguments to a call

   void process_call_arguments(CallNode *call, PhaseTransform *phase);

   // compute the escape state for the return value of a call

   void process_call_result(ProjNode *resproj, PhaseTransform *phase);

   // compute the escape state of a Phi.  This may be called multiple

   // times as new inputs are added to the Phi.

   void process_phi_escape(PhiNode *phi, PhaseTransform *phase);

   // compute the escape state of an ideal node.

   void record_escape_work(Node *n, PhaseTransform *phase);

   // walk the connection graph starting at the node corresponding to "n" and

   // add the index of everything it could point to, to "ptset".  This may cause

   // Phi's encountered to get (re)processed  (which requires "phase".)

   void PointsTo(VectorSet &ptset, Node * n, PhaseTransform *phase);

   //  Edge manipulation.  The "from_i" and "to_i" arguments are the

   //  node indices of the source and destination of the edge

   void add_pointsto_edge(uint from_i, uint to_i);

   void add_deferred_edge(uint from_i, uint to_i);

   void add_field_edge(uint from_i, uint to_i, int offs);

   // Add an edge to node given by "to_i" from any field of adr_i whose offset

   // matches "offset"  A deferred edge is added if to_i is a LocalVar, and

   // a pointsto edge is added if it is a JavaObject

   void add_edge_from_fields(uint adr, uint to_i, int offs);

   // Add a deferred  edge from node given by "from_i" to any field of adr_i whose offset

   // matches "offset"

   void add_deferred_edge_to_fields(uint from_i, uint adr, int offs);

   // Remove outgoing deferred edges from the node referenced by "ni".

   // Any outgoing edges from the target of the deferred edge are copied

   // to "ni".

   void remove_deferred(uint ni);

   Node_Array _node_map; // used for bookeeping during type splitting

                         // Used for the following purposes:

                         // Memory Phi    - most recent unique Phi split out

                         //                 from this Phi

                         // MemNode       - new memory input for this node

                         // ChecCastPP    - allocation that this is a cast of

                         // allocation    - CheckCastPP of the allocation

   void split_AddP(Node *addp, Node *base,  PhaseGVN  *igvn);

   PhiNode *create_split_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist, PhaseGVN  *igvn, bool &new_created);

   PhiNode *split_memory_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist, PhaseGVN  *igvn);

   Node *find_mem(Node *mem, int alias_idx, PhaseGVN  *igvn);

   // Propagate unique types created for unescaped allocated objects

   // through the graph

   void split_unique_types(GrowableArray<Node *>  &alloc_worklist);

   // manage entries in _node_map

   void  set_map(int idx, Node *n)        { _node_map.map(idx, n); }

   void  set_map_phi(int idx, PhiNode *p) { _node_map.map(idx, (Node *) p); }

   Node *get_map(int idx)                 { return _node_map[idx]; }

   PhiNode *get_map_phi(int idx) {

     Node *phi = _node_map[idx];

     return (phi == NULL) ? NULL : phi->as_Phi();

   }

   // Notify optimizer that a node has been modified

   // Node:  This assumes that escape analysis is run before

   //        PhaseIterGVN creation

   void record_for_optimizer(Node *n) {

     _compile->record_for_igvn(n);

   }

   // Set the escape state of a node

   void set_escape_state(uint ni, PointsToNode::EscapeState es);

   // bypass any casts and return the node they refer to

   Node * skip_casts(Node *n);

   // Get Compile object for current compilation.

   Compile *C() const        { return _compile; }

 public:

   ConnectionGraph(Compile *C);

   // record a Phi for later processing.

   void record_for_escape_analysis(Node *n);

   // process a node and  fill in its connection graph node

   void record_escape(Node *n, PhaseTransform *phase);

   // All nodes have been recorded, compute the escape information

   void compute_escape();

   // escape state of a node

   PointsToNode::EscapeState escape_state(Node *n, PhaseTransform *phase);

   bool hidden_alias(Node *n) {

     if (_collecting)

       return true;

     PointsToNode  ptn = _nodes->at_grow(n->_idx);

     return (ptn.escape_state() != PointsToNode::NoEscape) || ptn._hidden_alias;

   }

 #ifndef PRODUCT

   void dump();

 #endif

 };