--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/opto/escape.hpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,319 @@
+/*
+ * Copyright 2005-2006 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.
+ *
+ */
+
+//
+// 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
+};