//===- DSNode.h - Node definition for datastructure graphs ------*- C++ -*-===//
//
// Data structure graph nodes and some implementation of DSNodeHandle.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_DSNODE_H
#define LLVM_ANALYSIS_DSNODE_H

#include "llvm/Analysis/DSSupport.h"

//===----------------------------------------------------------------------===//
/// DSNode - Data structure node class
///
/// This class represents an untyped memory object of Size bytes.  It keeps
/// track of any pointers that have been stored into the object as well as the
/// different types represented in this object.
///
class DSNode {
  /// Referrers - Keep track of all of the node handles that point to this
  /// DSNode.  These pointers may need to be updated to point to a different
  /// node if this node gets merged with it.
  ///
  std::vector<DSNodeHandle*> Referrers;

  /// Links - Contains one entry for every sizeof(void*) bytes in this memory
  /// object.  Note that if the node is not a multiple of size(void*) bytes
  /// large, that there is an extra entry for the "remainder" of the node as
  /// well.  For this reason, nodes of 1 byte in size do have one link.
  ///
  std::vector<DSNodeHandle> Links;

  /// Globals - The list of global values that are merged into this node.
  ///
  std::vector<GlobalValue*> Globals;

  /// Type - Keep track of the current outer most type of this object, in
  /// addition to whether or not it has been indexed like an array or not.  If
  /// the isArray bit is set, the node cannot grow.
  ///
  DSTypeRec Ty;

  /// Size - The current size of the node.  This should be equal to the size of
  /// the current type record.
  ///
  unsigned Size;

  void operator=(const DSNode &); // DO NOT IMPLEMENT
public:
  enum NodeTy {
    ShadowNode  = 0,        // Nothing is known about this node...
    AllocaNode  = 1 << 0,   // This node was allocated with alloca
    HeapNode    = 1 << 1,   // This node was allocated with malloc
    GlobalNode  = 1 << 2,   // This node was allocated by a global var decl
    UnknownNode = 1 << 3,   // This node points to unknown allocated memory 
    Incomplete  = 1 << 4,   // This node may not be complete
    Modified    = 1 << 5,   // This node is modified in this context
    Read        = 1 << 6,   // This node is read in this context
#if 1
    DEAD        = 1 << 7,   // This node is dead and should not be pointed to
#endif
  };
  
  /// NodeType - A union of the above bits.  "Shadow" nodes do not add any flags
  /// to the nodes in the data structure graph, so it is possible to have nodes
  /// with a value of 0 for their NodeType.  Scalar and Alloca markers go away
  /// when function graphs are inlined.
  ///
  unsigned char NodeType;

  DSNode(enum NodeTy NT, const Type *T);
  DSNode(const DSNode &);

  ~DSNode() {
#ifndef NDEBUG
    dropAllReferences();  // Only needed to satisfy assertion checks...
    assert(Referrers.empty() && "Referrers to dead node exist!");
#endif
  }

  // Iterator for graph interface...
  typedef DSNodeIterator iterator;
  typedef DSNodeIterator const_iterator;
  inline iterator begin() const;   // Defined in DSGraphTraits.h
  inline iterator end() const;

  //===--------------------------------------------------
  // Accessors

  /// getSize - Return the maximum number of bytes occupied by this object...
  ///
  unsigned getSize() const { return Size; }

  // getType - Return the node type of this object...
  const DSTypeRec &getType() const { return Ty; }

  /// getReferrers - Return a list of the pointers to this node...
  ///
  const std::vector<DSNodeHandle*> &getReferrers() const { return Referrers; }

  /// hasNoReferrers - Return true if nothing is pointing to this node at all.
  ///
  bool hasNoReferrers() const { return Referrers.empty(); }

  /// isModified - Return true if this node may be modified in this context
  ///
  bool isModified() const { return (NodeType & Modified) != 0; }

  /// isRead - Return true if this node may be read in this context
  ///
  bool isRead() const { return (NodeType & Read) != 0; }


  /// hasLink - Return true if this memory object has a link in slot #LinkNo
  ///
  bool hasLink(unsigned Offset) const {
    assert((Offset & ((1 << DS::PointerShift)-1)) == 0 &&
           "Pointer offset not aligned correctly!");
    unsigned Index = Offset >> DS::PointerShift;
    assert(Index < Links.size() && "Link index is out of range!");
    return Links[Index].getNode();
  }

  /// getLink - Return the link at the specified offset.
  DSNodeHandle &getLink(unsigned Offset) {
    assert((Offset & ((1 << DS::PointerShift)-1)) == 0 &&
           "Pointer offset not aligned correctly!");
    unsigned Index = Offset >> DS::PointerShift;
    assert(Index < Links.size() && "Link index is out of range!");
    return Links[Index];
  }
  const DSNodeHandle &getLink(unsigned Offset) const {
    assert((Offset & ((1 << DS::PointerShift)-1)) == 0 &&
           "Pointer offset not aligned correctly!");
    unsigned Index = Offset >> DS::PointerShift;
    assert(Index < Links.size() && "Link index is out of range!");
    return Links[Index];
  }

  /// getNumLinks - Return the number of links in a node...
  ///
  unsigned getNumLinks() const { return Links.size(); }

  /// mergeTypeInfo - This method merges the specified type into the current
  /// node at the specified offset.  This may update the current node's type
  /// record if this gives more information to the node, it may do nothing to
  /// the node if this information is already known, or it may merge the node
  /// completely (and return true) if the information is incompatible with what
  /// is already known.
  ///
  /// This method returns true if the node is completely folded, otherwise
  /// false.
  ///
  bool mergeTypeInfo(const Type *Ty, unsigned Offset);

  /// foldNodeCompletely - If we determine that this node has some funny
  /// behavior happening to it that we cannot represent, we fold it down to a
  /// single, completely pessimistic, node.  This node is represented as a
  /// single byte with a single TypeEntry of "void" with isArray = true.
  ///
  void foldNodeCompletely();

  /// isNodeCompletelyFolded - Return true if this node has been completely
  /// folded down to something that can never be expanded, effectively losing
  /// all of the field sensitivity that may be present in the node.
  ///
  bool isNodeCompletelyFolded() const;

  /// setLink - Set the link at the specified offset to the specified
  /// NodeHandle, replacing what was there.  It is uncommon to use this method,
  /// instead one of the higher level methods should be used, below.
  ///
  void setLink(unsigned Offset, const DSNodeHandle &NH) {
    assert((Offset & ((1 << DS::PointerShift)-1)) == 0 &&
           "Pointer offset not aligned correctly!");
    unsigned Index = Offset >> DS::PointerShift;
    assert(Index < Links.size() && "Link index is out of range!");
    Links[Index] = NH;
  }

  /// getPointerSize - Return the size of a pointer for the current target.
  ///
  unsigned getPointerSize() const { return DS::PointerSize; }

  /// addEdgeTo - Add an edge from the current node to the specified node.  This
  /// can cause merging of nodes in the graph.
  ///
  void addEdgeTo(unsigned Offset, const DSNodeHandle &NH);

  /// mergeWith - Merge this node and the specified node, moving all links to
  /// and from the argument node into the current node, deleting the node
  /// argument.  Offset indicates what offset the specified node is to be merged
  /// into the current node.
  ///
  /// The specified node may be a null pointer (in which case, nothing happens).
  ///
  void mergeWith(const DSNodeHandle &NH, unsigned Offset);

  /// addGlobal - Add an entry for a global value to the Globals list.  This
  /// also marks the node with the 'G' flag if it does not already have it.
  ///
  void addGlobal(GlobalValue *GV);
  const std::vector<GlobalValue*> &getGlobals() const { return Globals; }
  std::vector<GlobalValue*> &getGlobals() { return Globals; }

  void print(std::ostream &O, const DSGraph *G) const;
  void dump() const;

  void dropAllReferences() {
    Links.clear();
  }

  /// remapLinks - Change all of the Links in the current node according to the
  /// specified mapping.
  void remapLinks(std::map<const DSNode*, DSNodeHandle> &OldNodeMap);

private:
  friend class DSNodeHandle;
  // addReferrer - Keep the referrer set up to date...
  void addReferrer(DSNodeHandle *H) { Referrers.push_back(H); }
  void removeReferrer(DSNodeHandle *H);
};


//===----------------------------------------------------------------------===//
// Define inline DSNodeHandle functions that depend on the definition of DSNode
//
inline void DSNodeHandle::setNode(DSNode *n) {
  if (N) N->removeReferrer(this);
  N = n;
  if (N) N->addReferrer(this);
  assert(!N || ((N->NodeType & DSNode::DEAD) == 0));
}

inline bool DSNodeHandle::hasLink(unsigned Num) const {
  assert(N && "DSNodeHandle does not point to a node yet!");
  return N->hasLink(Num+Offset);
}


/// getLink - Treat this current node pointer as a pointer to a structure of
/// some sort.  This method will return the pointer a mem[this+Num]
///
inline const DSNodeHandle &DSNodeHandle::getLink(unsigned Off) const {
  assert(N && "DSNodeHandle does not point to a node yet!");
  return N->getLink(Offset+Off);
}
inline DSNodeHandle &DSNodeHandle::getLink(unsigned Off) {
  assert(N && "DSNodeHandle does not point to a node yet!");
  return N->getLink(Off+Offset);
}

inline void DSNodeHandle::setLink(unsigned Off, const DSNodeHandle &NH) {
  assert(N && "DSNodeHandle does not point to a node yet!");
  N->setLink(Off+Offset, NH);
}

///  addEdgeTo - Add an edge from the current node to the specified node.  This
/// can cause merging of nodes in the graph.
///
inline void DSNodeHandle::addEdgeTo(unsigned Off, const DSNodeHandle &Node) {
  assert(N && "DSNodeHandle does not point to a node yet!");
  N->addEdgeTo(Off+Offset, Node);
}

/// mergeWith - Merge the logical node pointed to by 'this' with the node
/// pointed to by 'N'.
///
inline void DSNodeHandle::mergeWith(const DSNodeHandle &Node) {
  if (N != 0)
    N->mergeWith(Node, Offset);
  else     // No node to merge with, so just point to Node
    *this = Node;
}

#endif