alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (escape.hpp)

This example Java source code file (escape.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraycopynode, escapestate, fieldnode, growablearray, javaobjectnode, list, node, nodetype, null, pointstoiterator, pointstonode, pointstonode\:\:escapestate, scalarreplaceable, unique_node_list

The escape.hpp Java example source code

/*
 * 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#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);
  }

  // Utility function for nodes that load an object
  void add_objload_to_connection_graph(Node *n, Unique_Node_List *delayed_worklist);
  // 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");
    }
    return is_new;
  }

  // Add LocalVar node and edge if possible
  void add_local_var_and_edge(Node* n, PointsToNode::EscapeState es, Node* to,
                              Unique_Node_List *delayed_worklist) {
    PointsToNode* ptn = ptnode_adr(to->_idx);
    if (delayed_worklist != NULL) { // First iteration of CG construction
      add_local_var(n, es);
      if (ptn == NULL) {
        delayed_worklist->push(n);
        return; // Process it later.
      }
    } else {
      assert(ptn != NULL, "node should be registered");
    }
    add_edge(ptnode_adr(n->_idx), ptn);
 }
  // Helper functions
  bool   is_oop_field(Node* n, int offset, bool* unsafe);
 static Node* get_addp_base(Node *addp);
 static Node* find_second_addp(Node* addp, Node* n);
  // offset of a field reference
  int address_offset(Node* adr, PhaseTransform *phase);


  // Propagate unique types created for unescaped allocated objects
  // through the graph
  void split_unique_types(GrowableArray<Node *>  &alloc_worklist);

  // Helper methods for unique types split.
  bool split_AddP(Node *addp, Node *base);

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

  void  move_inst_mem(Node* n, GrowableArray<PhiNode *>  &orig_phis);
  Node* find_inst_mem(Node* mem, int alias_idx,GrowableArray<PhiNode *>  &orig_phi_worklist);
  Node* step_through_mergemem(MergeMemNode *mmem, int alias_idx, const TypeOopPtr *toop);


  GrowableArray<MergeMemNode*>  _mergemem_worklist; // List of all MergeMem nodes

  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

  // manage entries in _node_map

  void  set_map(Node* from, Node* to)  {
    ideal_nodes.push(from);
    _node_map.map(from->_idx, to);
  }

  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
  void record_for_optimizer(Node *n) {
    _igvn->_worklist.push(n);
    _igvn->add_users_to_worklist(n);
  }

  // Compute the escape information
  bool compute_escape();

public:
  ConnectionGraph(Compile *C, PhaseIterGVN *igvn);

  // Check for non-escaping candidates
  static bool has_candidates(Compile *C);

  // Perform escape analysis
  static void do_analysis(Compile *C, PhaseIterGVN *igvn);

  bool not_global_escape(Node *n);

#ifndef PRODUCT
  void dump(GrowableArray<PointsToNode*>& ptnodes_worklist);
#endif
};

#endif // SHARE_VM_OPTO_ESCAPE_HPP

Other Java examples (source code examples)

Here is a short list of links related to this Java escape.hpp source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.