//===- DataStructure.cpp - Implement the core data structure analysis -----===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the core data structure functionality.
//
//===----------------------------------------------------------------------===//

#include "dsa/DSGraphTraits.h"
#include "dsa/DataStructure.h"
#include "dsa/DSGraph.h"
#include "dsa/DSSupport.h"
#include "dsa/DSNode.h"
#include "dsa/stl_util.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Timer.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/GlobalAlias.h"

#include <iostream>
#include <algorithm>
using namespace llvm;

#define COLLAPSE_ARRAYS_AGGRESSIVELY 0
namespace {
  STATISTIC (NumCallNodesMerged               , "Number of call nodes merged");
  STATISTIC (NumDNE                           , "Number of nodes removed by reachability");
  STATISTIC (NumTrivialDNE                    , "Number of nodes trivially removed");
  STATISTIC (NumTrivialGlobalDNE              , "Number of globals trivially removed");
  STATISTIC (NumFiltered                      , "Number of calls filtered");
  
  static cl::opt<bool> noDSACallConv("dsa-no-filter-callcc",
         cl::desc("Don't filter call sites based on calling convention."),
         cl::Hidden,
         cl::init(false));
  static cl::opt<bool> noDSACallNumArgs("dsa-no-filter-numargs",
         cl::desc("Don't filter call sites based on number of arguments."),
         cl::Hidden,
         cl::init(false));
  static cl::opt<bool> noDSACallVA("dsa-no-filter-vararg",
         cl::desc("Don't filter call sites based on vararg presense"),
         cl::Hidden,
         cl::init(true));
  static cl::opt<bool> noDSACallFP("dsa-no-filter-intfp",
         cl::desc("Don't filter call sites based on implicit integer to FP conversion"),
         cl::Hidden,
         cl::init(false));
}

extern cl::opt<bool> TypeInferenceOptimize;

// Determines if the DSGraph 'should' have a node for a given value.
static bool shouldHaveNodeForValue(const Value *V) {
  // Peer through casts
  V = V->stripPointerCasts();
  
  // Only pointers get nodes
  if (!isa<PointerType>(V->getType())) return false;

  // Undef values, even ones of pointer type, don't get nodes.
  if (isa<UndefValue>(V)) return false;

  if (isa<ConstantPointerNull>(V))
    return false;

  // Use the Aliasee of GlobalAliases
  // FIXME: This check might not be required, it's here because
  // something similar is done in the Local pass.
  if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
    return shouldHaveNodeForValue(GA->getAliasee());

  return true;
}

/// getFunctionNames - Return a space separated list of the name of the
/// functions in this graph (if any)
std::string DSGraph::getFunctionNames() const {
  switch (getReturnNodes().size()) {
  case 0: return "Globals graph";
  case 1: return retnodes_begin()->first->getName();
  default:
    std::string Return;
    for (DSGraph::retnodes_iterator I = retnodes_begin();
         I != retnodes_end(); ++I)
      Return += I->first->getName().str() + " ";
    Return.erase(Return.end()-1, Return.end());   // Remove last space character
    return Return;
  }
}


DSGraph::DSGraph(DSGraph* G, EquivalenceClasses<const GlobalValue*> &ECs,
                 SuperSet<Type*>& tss,
                 unsigned CloneFlags)
  : GlobalsGraph(0), ScalarMap(ECs), TD(G->TD), TypeSS(tss) {
  UseAuxCalls = false;
  cloneInto(G, CloneFlags);
}

DSGraph::~DSGraph() {
  FunctionCalls.clear();
  AuxFunctionCalls.clear();
  ScalarMap.clear();
  ReturnNodes.clear();
  VANodes.clear();

  // Drop all intra-node references, so that assertions don't fail...
  for (node_iterator NI = node_begin(), E = node_end(); NI != E; ++NI)
    NI->dropAllReferences();

  // Free all of the nodes.
  Nodes.clear();
}

// dump - Allow inspection of graph in a debugger.
void DSGraph::dump() const { print(errs()); }

void DSGraph::removeFunctionCalls(Function& F) {
  FunctionListTy::iterator Erase = FunctionCalls.end();
  for (FunctionListTy::iterator I = FunctionCalls.begin();
       I != Erase; ) {
    if (I->isDirectCall() && I->getCalleeFunc() == &F)
      std::swap(*I, *--Erase);
    else
      ++I;
  }
  FunctionCalls.erase(Erase, FunctionCalls.end());

  Erase = AuxFunctionCalls.end();
  for (FunctionListTy::iterator I = AuxFunctionCalls.begin();
       I != Erase; ) {
    if (I->isDirectCall() && I->getCalleeFunc() == &F)
      std::swap(*I, *--Erase);
    else
      ++I;
  }
  AuxFunctionCalls.erase(Erase, AuxFunctionCalls.end());
}

/// addObjectToGraph - This method can be used to add global, stack, and heap
/// objects to the graph.  This can be used when updating DSGraphs due to the
/// introduction of new temporary objects.  The new object is not pointed to
/// and does not point to any other objects in the graph.
DSNode *DSGraph::addObjectToGraph(Value *Ptr, bool UseDeclaredType) {
  assert(isa<PointerType>(Ptr->getType()) && "Ptr is not a pointer!");
  DSNode *N = new DSNode(this);
  assert(ScalarMap[Ptr].isNull() && "Object already in this graph!");
  ScalarMap[Ptr] = N;

  if (GlobalValue *GV = dyn_cast<GlobalValue>(Ptr)) {
    N->addGlobal(GV);
//  } else if (isa<MallocInst>(Ptr)) {
//   N->setHeapMarker();
  } else if (isa<AllocaInst>(Ptr)) {
    N->setAllocaMarker();
  } else {
    assert(0 && "Illegal memory object input!");
  }
  return N;
}


/// cloneInto - Clone the specified DSGraph into the current graph.  The
/// translated ScalarMap for the old function is filled into the ScalarMap
/// for the graph, the translated ReturnNodes map is returned into
/// ReturnNodes, and the translated VANodes map is return into VANodes.
///
/// The CloneFlags member controls various aspects of the cloning process.
///
void DSGraph::cloneInto( DSGraph* G, unsigned CloneFlags) {
  assert(G != this && "Cannot clone graph into itself!");

  NodeMapTy OldNodeMap;

  // Remove alloca or mod/ref bits as specified...
  unsigned BitsToClear = ((CloneFlags & StripAllocaBit)? DSNode::AllocaNode : 0)
    | ((CloneFlags & StripModRefBits)? (DSNode::ModifiedNode | DSNode::ReadNode) : 0)
    | ((CloneFlags & StripIncompleteBit)? DSNode::IncompleteNode : 0);
  BitsToClear |= DSNode::DeadNode;  // Clear dead flag...

  for (node_const_iterator I = G->node_begin(), E = G->node_end(); I != E; ++I) {
    assert(!I->isForwarding() &&
           "Forward nodes shouldn't be in node list!");
    DSNode *New = new DSNode(*I, this);
    New->maskNodeTypes(~BitsToClear);
    OldNodeMap[I] = New;
  }

  // Rewrite the links in the new nodes to point into the current graph now.
  // Note that we don't loop over the node's list to do this.  The problem is
  // that remaping links can cause recursive merging to happen, which means
  // that node_iterator's can get easily invalidated!  Because of this, we
  // loop over the OldNodeMap, which contains all of the new nodes as the
  // .second element of the map elements.  Also note that if we remap a node
  // more than once, we won't break anything.
  for (NodeMapTy::iterator I = OldNodeMap.begin(), E = OldNodeMap.end();
       I != E; ++I)
    I->second.getNode()->remapLinks(OldNodeMap);

  // Copy the scalar map... merging all of the global nodes...
  for (DSScalarMap::const_iterator I = G->ScalarMap.begin(),
         E = G->ScalarMap.end(); I != E; ++I) {
    DSNodeHandle &MappedNode = OldNodeMap[I->second.getNode()];
    DSNodeHandle &H = ScalarMap.getRawEntryRef(I->first);
    DSNode *MappedNodeN = MappedNode.getNode();
    H.mergeWith(DSNodeHandle(MappedNodeN,
                             I->second.getOffset()+MappedNode.getOffset()));
  }

  if (!(CloneFlags & DontCloneCallNodes)) {
    // Copy the function calls list.
    for (fc_iterator I = G->fc_begin(), E = G->fc_end(); I != E; ++I)
      FunctionCalls.push_back(DSCallSite(*I, OldNodeMap));
  }

  if (!(CloneFlags & DontCloneAuxCallNodes)) {
    // Copy the auxiliary function calls list.
    for (afc_iterator I = G->afc_begin(), E = G->afc_end(); I != E; ++I)
      AuxFunctionCalls.push_back(DSCallSite(*I, OldNodeMap));
  }

  // Map the return node pointers over...
  for (retnodes_iterator I = G->retnodes_begin(),
         E = G->retnodes_end(); I != E; ++I) {
    const DSNodeHandle &Ret = I->second;
    DSNodeHandle &MappedRet = OldNodeMap[Ret.getNode()];
    DSNode *MappedRetN = MappedRet.getNode();
    ReturnNodes.insert(std::make_pair(I->first,
                                      DSNodeHandle(MappedRetN,
                                     MappedRet.getOffset()+Ret.getOffset())));
  }

  // Map the VA node pointers over...
  for (vanodes_iterator I = G->vanodes_begin(),
         E = G->vanodes_end(); I != E; ++I) {
    const DSNodeHandle &VarArg = I->second;
    DSNodeHandle &MappedVarArg = OldNodeMap[VarArg.getNode()];
    DSNode *MappedVarArgN = MappedVarArg.getNode();
    VANodes.insert(std::make_pair(I->first,
                   DSNodeHandle(MappedVarArgN,
                                MappedVarArg.getOffset()+VarArg.getOffset())));
  }
}

/// spliceFrom - Logically perform the operation of cloning the RHS graph into
/// this graph, then clearing the RHS graph.  Instead of performing this as
/// two seperate operations, do it as a single, much faster, one.
///
void DSGraph::spliceFrom(DSGraph* RHS) {
  assert(this != RHS && "Splicing self");
  // Change all of the nodes in RHS to think we are their parent.
  for (NodeListTy::iterator I = RHS->Nodes.begin(), E = RHS->Nodes.end();
       I != E; ++I)
    I->setParentGraph(this);
  // Take all of the nodes.
  splice(Nodes, RHS->Nodes);

  // Take all of the calls.
  splice(FunctionCalls, RHS->FunctionCalls);
  splice(AuxFunctionCalls, RHS->AuxFunctionCalls);

  // Take all of the return nodes.
  splice(ReturnNodes, RHS->ReturnNodes);

  // Same for the VA nodes
  splice(VANodes, RHS->VANodes);

  // Merge the scalar map in.
  ScalarMap.spliceFrom(RHS->ScalarMap);
}

/// getFunctionArgumentsForCall - Given a function that is currently in this
/// graph, return the DSNodeHandles that correspond to the pointer-compatible
/// function arguments.  The vector is filled in with the return value (or
/// null if it is not pointer compatible), a vararg node (null if not
/// applicable) followed by all of the pointer-compatible arguments.
void DSGraph::getFunctionArgumentsForCall(const Function *F,
                                       std::vector<DSNodeHandle> &Args) const {
  Args.push_back(getReturnNodeFor(*F));
  Args.push_back(getVANodeFor(*F));
  for (Function::const_arg_iterator AI = F->arg_begin(), E = F->arg_end();
       AI != E; ++AI)
    if (isa<PointerType>(AI->getType())) {
      Args.push_back(getNodeForValue(AI));
      assert(!Args.back().isNull() && "Pointer argument w/o scalarmap entry!?");
    }
}

namespace {
  // HackedGraphSCCFinder - This is used to find nodes that have a path from the
  // node to a node cloned by the ReachabilityCloner object contained.  To be
  // extra obnoxious it ignores edges from nodes that are globals, and truncates
  // search at RC marked nodes.  This is designed as an object so that
  // intermediate results can be memoized across invocations of
  // PathExistsToClonedNode.
  struct HackedGraphSCCFinder {
    ReachabilityCloner &RC;
    unsigned CurNodeId;
    std::vector<const DSNode*> SCCStack;
    std::map<const DSNode*, std::pair<unsigned, bool> > NodeInfo;

    HackedGraphSCCFinder(ReachabilityCloner &rc) : RC(rc), CurNodeId(1) {
      // Remove null pointer as a special case.
      NodeInfo[0] = std::make_pair(0, false);
    }

    std::pair<unsigned, bool> &VisitForSCCs(const DSNode *N);

    bool PathExistsToClonedNode(const DSNode *N) {
      return VisitForSCCs(N).second;
    }

    bool PathExistsToClonedNode(const DSCallSite &CS) {
      if (PathExistsToClonedNode(CS.getRetVal().getNode()))
        return true;
      if (CS.isIndirectCall() && PathExistsToClonedNode(CS.getCalleeNode()))
        return true;
      for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i)
        if (PathExistsToClonedNode(CS.getPtrArg(i).getNode()))
          return true;
      if (PathExistsToClonedNode(CS.getVAVal().getNode()))
        return true;
      return false;
    }
  };
}

std::pair<unsigned, bool> &HackedGraphSCCFinder::
VisitForSCCs(const DSNode *N) {
  std::map<const DSNode*, std::pair<unsigned, bool> >::iterator
    NodeInfoIt = NodeInfo.lower_bound(N);
  if (NodeInfoIt != NodeInfo.end() && NodeInfoIt->first == N)
    return NodeInfoIt->second;

  unsigned Min = CurNodeId++;
  unsigned MyId = Min;
  std::pair<unsigned, bool> &ThisNodeInfo =
    NodeInfo.insert(NodeInfoIt,
                    std::make_pair(N, std::make_pair(MyId, false)))->second;


  // Base case: if this does reach the cloned graph portion... it does. :)
  if (RC.hasClonedNode(N)) {
    ThisNodeInfo.second = true;
    return ThisNodeInfo;
  }
  // Base case: if we find a global, this doesn't reach the cloned graph
  // portion.
  if (N->isGlobalNode()) {
    ThisNodeInfo.second = false;
    return ThisNodeInfo;
  }

  SCCStack.push_back(N);

  // Otherwise, check all successors.
  bool AnyDirectSuccessorsReachClonedNodes = false;
  for (DSNode::const_edge_iterator EI = N->edge_begin(), EE = N->edge_end();
       EI != EE; ++EI)
    if (DSNode * Succ = EI->second.getNode()) {
      std::pair<unsigned, bool> &SuccInfo = VisitForSCCs(Succ);
      if (SuccInfo.first < Min) Min = SuccInfo.first;
      AnyDirectSuccessorsReachClonedNodes |= SuccInfo.second;
    }

  if (Min != MyId)
    return ThisNodeInfo;  // Part of a large SCC.  Leave self on stack.

  if (SCCStack.back() == N) {  // Special case single node SCC.
    SCCStack.pop_back();
    ThisNodeInfo.second = AnyDirectSuccessorsReachClonedNodes;
    return ThisNodeInfo;
  }

  // Find out if any direct successors of any node reach cloned nodes.
  if (!AnyDirectSuccessorsReachClonedNodes)
    for (unsigned i = SCCStack.size() - 1; SCCStack[i] != N; --i)
      for (DSNode::const_edge_iterator EI = N->edge_begin(), EE = N->edge_end();
           EI != EE; ++EI)
        if (DSNode * N = EI->second.getNode())
          if (NodeInfo[N].second) {
            AnyDirectSuccessorsReachClonedNodes = true;
            goto OutOfLoop;
          }
OutOfLoop:
  // If any successor reaches a cloned node, mark all nodes in this SCC as
  // reaching the cloned node.
  if (AnyDirectSuccessorsReachClonedNodes)
    while (SCCStack.back() != N) {
      NodeInfo[SCCStack.back()].second = true;
      SCCStack.pop_back();
    }
  SCCStack.pop_back();
  ThisNodeInfo.second = AnyDirectSuccessorsReachClonedNodes;
  return ThisNodeInfo;
}

/// mergeInCallFromOtherGraph - This graph merges in the minimal number of
/// nodes from G2 into 'this' graph, merging the bindings specified by the
/// call site (in this graph) with the bindings specified by the vector in G2.
/// The two DSGraphs must be different.
///
void DSGraph::mergeInGraph(const DSCallSite &CS,
                           std::vector<DSNodeHandle> &Args,
                           const DSGraph &Graph, unsigned CloneFlags) {
  assert((CloneFlags & DontCloneCallNodes) &&
         "Doesn't support copying of call nodes!");

  // If this is not a recursive call, clone the graph into this graph...
  if (&Graph == this) {
    // Merge the return value with the return value of the context.
    Args[0].mergeWith(CS.getRetVal());

    // Merge var-arg node
    Args[1].mergeWith(CS.getVAVal());

    // Resolve all of the function arguments.
    for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i) {
      if (i == Args.size()-2)
        break;

      // Add the link from the argument scalar to the provided value.
      Args[i+2].mergeWith(CS.getPtrArg(i));
    }
    return;
  }

  // Clone the callee's graph into the current graph, keeping track of where
  // scalars in the old graph _used_ to point, and of the new nodes matching
  // nodes of the old graph.
  ReachabilityCloner RC(this, &Graph, CloneFlags);

  // Map the return node pointer over.
  if (!CS.getRetVal().isNull())
    RC.merge(CS.getRetVal(), Args[0]);

  // Map the variable arguments
  if (!CS.getVAVal().isNull())
    RC.merge(CS.getVAVal(), Args[1]);

  // Map over all of the arguments.
  for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i) {
    if (i == Args.size()-2)
      break;

    // Add the link from the argument scalar to the provided value.
    RC.merge(CS.getPtrArg(i), Args[i+2]);
  }

  // We generally don't want to copy global nodes or aux calls from the callee
  // graph to the caller graph.  However, we have to copy them if there is a
  // path from the node to a node we have already copied which does not go
  // through another global.  Compute the set of node that can reach globals and
  // aux call nodes to copy over, then do it.
  std::vector<const DSCallSite*> AuxCallToCopy;
  std::vector<const GlobalValue*> GlobalsToCopy;

  // NodesReachCopiedNodes - Memoize results for efficiency.  Contains a
  // true/false value for every visited node that reaches a copied node without
  // going through a global.
  HackedGraphSCCFinder SCCFinder(RC);

  if (!(CloneFlags & DontCloneAuxCallNodes))
    for (afc_const_iterator I = Graph.afc_begin(), E = Graph.afc_end(); I!=E; ++I)
      if (!I->isUnresolvable() && SCCFinder.PathExistsToClonedNode(*I))
        AuxCallToCopy.push_back(&*I);

  // Copy aux calls that are needed.
  // Copy these before calculating the globals to be copied, as there might be
  // globals that reach the nodes cloned due to aux calls.
  for (unsigned i = 0, e = AuxCallToCopy.size(); i != e; ++i)
    AuxFunctionCalls.push_back(DSCallSite(*AuxCallToCopy[i], RC));

  const DSScalarMap &GSM = Graph.getScalarMap();
  for (DSScalarMap::global_iterator GI = GSM.global_begin(),
         E = GSM.global_end(); GI != E; ++GI) {
    DSNode *GlobalNode = Graph.getNodeForValue(*GI).getNode();
    for (DSNode::edge_iterator EI = GlobalNode->edge_begin(),
           EE = GlobalNode->edge_end(); EI != EE; ++EI)
      if (SCCFinder.PathExistsToClonedNode(EI->second.getNode())) {
        GlobalsToCopy.push_back(*GI);
        break;
      }
  }

  // Copy globals that are needed.
  for (unsigned i = 0, e = GlobalsToCopy.size(); i != e; ++i)
    RC.getClonedNH(Graph.getNodeForValue(GlobalsToCopy[i]));
}


/// mergeInGraph - The method is used for merging graphs together.  If the
/// argument graph is not *this, it makes a clone of the specified graph, then
/// merges the nodes specified in the call site with the formal arguments in the
/// graph.
///
void DSGraph::mergeInGraph(const DSCallSite &CS, const Function &F,
                           const DSGraph &Graph, unsigned CloneFlags) {
  // Set up argument bindings.
  std::vector<DSNodeHandle> Args;
  Graph.getFunctionArgumentsForCall(&F, Args);

  mergeInGraph(CS, Args, Graph, CloneFlags);
}

/// getCallSiteForArguments - Get the arguments and return value bindings for
/// the specified function in the current graph.
///
DSCallSite DSGraph::getCallSiteForArguments(const Function &F) const {
  std::vector<DSNodeHandle> Args;

  for (Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
    if (isa<PointerType>(I->getType()))
      Args.push_back(getNodeForValue(I));

  return DSCallSite(CallSite(), getReturnNodeFor(F), getVANodeFor(F), &F, Args);
}

/// getDSCallSiteForCallSite - Given an LLVM CallSite object that is live in
/// the context of this graph, return the DSCallSite for it.
DSCallSite DSGraph::getDSCallSiteForCallSite(CallSite CS) const {
  DSNodeHandle RetVal, VarArg;
  Instruction *I = CS.getInstruction();
  if (shouldHaveNodeForValue(I))
    RetVal = getNodeForValue(I);

  //FIXME: Here we trust the signature of the callsite to determine which arguments
  //are var-arg and which are fixed.  Apparently we can't assume this, but I'm not sure
  //of a better way.  For now, this assumption is known limitation.
  const FunctionType *CalleeFuncType = DSCallSite::FunctionTypeOfCallSite(CS);
  int NumFixedArgs = CalleeFuncType->getNumParams();
  
  // Sanity check--this really, really shouldn't happen
  if (!CalleeFuncType->isVarArg())
    assert(CS.arg_size() == static_cast<unsigned>(NumFixedArgs) &&
        "Too many arguments/incorrect function signature!");

  std::vector<DSNodeHandle> Args;
  Args.reserve(CS.arg_end()-CS.arg_begin());

  // Calculate the arguments vector...
  for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
    if (isa<PointerType>((*I)->getType())) {
      DSNodeHandle ArgNode; // Initially empty
      if (shouldHaveNodeForValue(*I)) ArgNode = getNodeForValue(*I);
      if (I - CS.arg_begin() < NumFixedArgs) {
        Args.push_back(ArgNode);
      } else {
        VarArg.mergeWith(ArgNode);
      }
    }

  //
  // Add a new function call entry.  We get the called value from the call site
  // and strip pointer casts instead of asking the CallSite class to do that
  // since CallSite::getCalledFunction() returns 0 if the called value is
  // a bit-casted function constant.
  //
  if (Function *F=dyn_cast<Function>(CS.getCalledValue()->stripPointerCasts()))
    return DSCallSite(CS, RetVal, VarArg, F, Args);
  else
    return DSCallSite(CS, RetVal, VarArg,
                      getNodeForValue(CS.getCalledValue()).getNode(), Args);
}


// markIncompleteNodes - Mark the specified node as having contents that are not
// known with the current analysis we have performed.  Because a node makes all
// of the nodes it can reach incomplete if the node itself is incomplete, we
// must recursively traverse the data structure graph, marking all reachable
// nodes as incomplete.
//
static void markIncompleteNode(DSNode *N) {
  // Stop recursion if no node, or if node already marked...
  if (N == 0 || N->isIncompleteNode()) return;

  // Actually mark the node
  N->setIncompleteMarker();

  // Recursively process children...
  for (DSNode::edge_iterator ii = N->edge_begin(), ee = N->edge_end();
       ii != ee; ++ii)
    markIncompleteNode(ii->second.getNode());
}

static void markIncomplete(DSCallSite &Call) {
  // Then the return value is certainly incomplete!
  markIncompleteNode(Call.getRetVal().getNode());

  markIncompleteNode(Call.getVAVal().getNode());

  // All objects pointed to by function arguments are incomplete!
  for (unsigned i = 0, e = Call.getNumPtrArgs(); i != e; ++i)
    markIncompleteNode(Call.getPtrArg(i).getNode());
}

// markIncompleteNodes - Traverse the graph, identifying nodes that may be
// modified by other functions that have not been resolved yet.  This marks
// nodes that are reachable through three sources of "unknownness":
//
//  Global Variables, Function Calls, and Incoming Arguments
//
// For any node that may have unknown components (because something outside the
// scope of current analysis may have modified it), the 'Incomplete' flag is
// added to the NodeType.
//
void DSGraph::markIncompleteNodes(unsigned Flags) {
  // Mark any incoming arguments as incomplete.
  if (Flags & DSGraph::MarkFormalArgs) {
    for (ReturnNodesTy::iterator FI = ReturnNodes.begin(), E =ReturnNodes.end();
         FI != E; ++FI) {
      const Function &F = *FI->first;
      for (Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end();
           I != E; ++I)
        if (isa<PointerType>(I->getType()))
          markIncompleteNode(getNodeForValue(I).getNode());
      markIncompleteNode(FI->second.getNode());
    }
    // Mark all vanodes as incomplete (they are also arguments)
    for (vanodes_iterator I = vanodes_begin(), E = vanodes_end();
        I != E; ++I)
      markIncompleteNode(I->second.getNode());
  }

  // Mark stuff passed into functions calls as being incomplete.
  if (!shouldUseAuxCalls())
    for (FunctionListTy::iterator I = FunctionCalls.begin(),
           E = FunctionCalls.end(); I != E; ++I)
      markIncomplete(*I);
  else
    for (FunctionListTy::iterator I = AuxFunctionCalls.begin(),
           E = AuxFunctionCalls.end(); I != E; ++I)
      markIncomplete(*I);

  // Mark all global nodes as incomplete that aren't initialized and constant.
  if ((Flags & DSGraph::IgnoreGlobals) == 0) 
    for (DSScalarMap::global_iterator I = ScalarMap.global_begin(),
        E = ScalarMap.global_end(); I != E; ++I)
      if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(*I)) {
        if (!(GV->hasInitializer() && GV->isConstant())){
          markIncompleteNode(ScalarMap[GV].getNode());
        }
      }

  // Mark any node with the VAStart flag as incomplete.
  if (Flags & DSGraph::MarkVAStart) {
    for (node_iterator i=node_begin(); i != node_end(); ++i) {
      if (i->isVAStartNode())
        markIncompleteNode(i);
    }
  }
}

//
// Function: markExternalNode()
//
// Description:
//  Marks the specified node, and all that's reachable from it, as external.
//  It uses 'processedNodes' to track recursion.
//
static void markExternalNode(DSNode *N, DenseSet<DSNode *> & processedNodes) {
  // Stop recursion if no node, or if node already processed
  if (N == 0 || processedNodes.count(N) ) return;

  processedNodes.insert(N);

  // Actually mark the node
  N->setExternalMarker();
  
  // FIXME: Should we 'collapse' the node as well?

  // Recursively process children...
  for (DSNode::edge_iterator ii = N->edge_begin(), ee = N->edge_end();
       ii != ee; ++ii)
    markExternalNode(ii->second.getNode(), processedNodes);
}

// markExternal --marks the specified callsite external, using 'processedNodes' to track recursion.
static void markExternal(const DSCallSite &Call, DenseSet<DSNode *> & processedNodes) {
  markExternalNode(Call.getRetVal().getNode(), processedNodes);

  markExternalNode(Call.getVAVal().getNode(), processedNodes);

  // Mark all pointer arguments...
  for (unsigned i = 0, e = Call.getNumPtrArgs(); i != e; ++i)
    markExternalNode(Call.getPtrArg(i).getNode(), processedNodes);
}

//
// Method: propagateExternal()
//
// Description:
//  Walk the given DSGraph and ensure that, within this graph,
//  everything reachable from a node marked External is also marked External.
//
static void propagateExternal(DSGraph * G, DenseSet<DSNode *> & processedNodes) {
  DSGraph::node_iterator I = G->node_begin(),
                         E = G->node_end();
  for ( ; I != E; ++I ) {
    if (I->isExternalNode())
      markExternalNode(&*I, processedNodes);
  }
}

//
// Method: computeIntPtrFlags()
//
// Description:
//  Mark all nodes that must get P2 flags due to type overlap.
//
void DSGraph::computeIntPtrFlags() {
  DSGraph::node_iterator I = node_begin(),
                         E = node_end();
  for ( ; I != E; ++I ) {
    I->markIntPtrFlags();
  }
}

// computeExternalFlags -- mark all reachable from external as external
void DSGraph::computeExternalFlags(unsigned Flags) {

  DenseSet<DSNode *> processedNodes;

  // Reset if indicated
  if (Flags & ResetExternal) {
    maskNodeTypes(~DSNode::ExternalNode);
  }

  // Make sure that everything reachable from something already external is
  // also external
  propagateExternal(this, processedNodes);

  // If requested, we mark all functions (their formals) in this
  // graph (read: SCC) as external.
  if (Flags & MarkFormalsExternal) {
    for (ReturnNodesTy::iterator FI = ReturnNodes.begin(), E =ReturnNodes.end();
        FI != E; ++FI) {
      const Function &F = *FI->first;
      // Mark its arguments, return value (and vanode) as external.
      for (Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end();
          I != E; ++I){
        if(TypeInferenceOptimize) {
          if(I->getName().str() == "argv")
            continue;
        }
        if (isa<PointerType>(I->getType()))
          markExternalNode(getNodeForValue(I).getNode(), processedNodes);
      }
      markExternalNode(FI->second.getNode(), processedNodes);
      markExternalNode(getVANodeFor(F).getNode(), processedNodes);
    }
  }

  // If requested, look for callsites to external functions and make
  // sure that they're marked external as appropriate.
  if (Flags & ProcessCallSites) {
    // Get List of all callsites, resolved or not...
    std::list<DSCallSite> AllCalls;
    AllCalls.insert(AllCalls.begin(), fc_begin(), fc_end());
    AllCalls.insert(AllCalls.begin(), afc_begin(), afc_end());

    // ...and use that list to find all CallSites that call external functions
    // and mark them accordingly.
    for (std::list<DSCallSite>::iterator I = AllCalls.begin(),
        E = AllCalls.end(); I != E; ++I) {
      bool shouldBeMarkedExternal = false;

      // Figure out what this callsite calls...
      std::vector<const Function *> Functions;
      if (I->isDirectCall())
        Functions.push_back(I->getCalleeFunc());
      else
        I->getCalleeNode()->addFullFunctionList(Functions);

      // ...And examine each callee:
      for (std::vector<const Function *>::iterator II = Functions.begin(),
          EE = Functions.end();
          (II != EE) && !shouldBeMarkedExternal; ++II) {

        // Calls to external functions should be marked external
        shouldBeMarkedExternal |= (*II)->isDeclaration();
      }

      // If this callsite can call external code, it better be the case that
      // the pointer arguments and the return values are all marked external
      // (and what's reachable from them)
      if (shouldBeMarkedExternal) {
        markExternal(*I, processedNodes);
      }
    }
  }

  // Finally handle all external globals...
  for (DSScalarMap::global_iterator I = ScalarMap.global_begin(),
      E = ScalarMap.global_end(); I != E; ++I) {
    if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(*I)) {
      if(TypeInferenceOptimize) {
        if(GV->getName().str() == "stderr"){
          continue;
        }
        if(GV->getName().str() == "stdout"){
          continue;
        }
        if(GV->getName().str() == "stdin"){
          continue;
        }
      }
      // If the global is external... mark it as such!
      DSNode * N = ScalarMap[GV].getNode();
      if (!(GV->hasInternalLinkage() || GV->hasPrivateLinkage()) || N->isExternalNode())
        markExternalNode(N, processedNodes);
    }
  }

}

static inline void killIfUselessEdge(DSNodeHandle &Edge) {
  if (DSNode * N = Edge.getNode()) // Is there an edge?
    if (N->getNumReferrers() == 1)  // Does it point to a lonely node?
      // No interesting info?
      if ((N->getNodeFlags() & ~DSNode::IncompleteNode) == 0
          && N->hasNoType()
          && !N->isNodeCompletelyFolded())
        Edge.setTo(0, 0);  // Kill the edge!
}

static void removeIdenticalCalls(DSGraph::FunctionListTy &Calls) {
  // Remove trivially identical function calls

  unsigned NumDeleted = 0;

  // First, scan through killing off useless edges and trivially dead callsites
  for (DSGraph::FunctionListTy::iterator I = Calls.begin(), E = Calls.end();
       I != E; ) {
    DSCallSite &CS = *I;

    // If the return value or any arguments point to a void node with no
    // information at all in it, and the call node is the only node to point
    // to it, remove the edge to the node (killing the node).
    //
    killIfUselessEdge(CS.getRetVal());
    killIfUselessEdge(CS.getVAVal());
    for (unsigned a = 0, e = CS.getNumPtrArgs(); a != e; ++a)
      killIfUselessEdge(CS.getPtrArg(a));

    // If this is an indirect callsite, but the Callee DSNode isn't
    // tied to from anything, remove it trivially.
    if (CS.isIndirectCall()) {
      DSNode *Callee = CS.getCalleeNode();
      if (Callee->getNumReferrers() == 1 && Callee->isCompleteNode() &&
          Callee->isEmptyGlobals()) {  // No useful info?
        DEBUG(errs() << "WARNING: Useless call site found.\n");
        I = Calls.erase(I);
        E = Calls.end();
        ++NumDeleted;
        continue;
      }
    }
    ++I;
  }

  // Now scan for redundant indirect callsites
  // First, sort by callee (using DSCallSite::operator<)
  sort(Calls);

  // Then find adjacent callsites that are equivalent and handle accordingly
  DSGraph::FunctionListTy::iterator I = Calls.begin();
  while((I = std::adjacent_find(I, Calls.end())) != Calls.end()) {
    DSGraph::FunctionListTy::iterator Second = I;
    DSCallSite &DCS1 = *I, &DCS2 = *++Second;

    if (DCS1.isIndirectCall()) {
      // Merge them together (into the first one)
      DCS1.mergeWith(DCS2);
    }

    // Remove the second one
    ++NumDeleted;
    Calls.erase(Second);

    // Carry on, searching from 'I' (first one)...
  }

  // Track the number of call nodes merged away...
  NumCallNodesMerged += NumDeleted;

  if (NumDeleted)
    DEBUG(errs() << "Merged " << NumDeleted << " call nodes.\n");
}
// removeTriviallyDeadNodes - After the graph has been constructed, this method
// removes all unreachable nodes that are created because they got merged with
// other nodes in the graph.  These nodes will all be trivially unreachable, so
// we don't have to perform any non-trivial analysis here.
//
void DSGraph::removeTriviallyDeadNodes() {
  /// NOTE: This code is disabled.  This slows down DSA on 177.mesa
  /// substantially!

  // Loop over all of the nodes in the graph, calling getNode on each field.
  // This will cause all nodes to update their forwarding edges, causing
  // forwarded nodes to be delete-able.  Further, reclaim any memory used by
  // useless edge or type entries
  for (node_iterator NI = node_begin(), E = node_end(); NI != E; ++NI)
    for (DSNode::edge_iterator ii = NI->edge_begin(), ee = NI->edge_end();
         ii != ee; ++ii) {
      ii->second.getNode()->cleanEdges();
    }

  // Likewise, forward any edges from the scalar nodes.  While we are at it,
  // clean house a bit.
  for (DSScalarMap::iterator I = ScalarMap.begin(), E = ScalarMap.end();
       I != E; ++I)
    I->second.getNode();

  bool isGlobalsGraph = !GlobalsGraph;

  for (NodeListTy::iterator NI = Nodes.begin(), E = Nodes.end(); NI != E; ) {
    DSNode &Node = *NI;

    // Do not remove *any* global nodes in the globals graph.
    // This is a special case because such nodes may not have I, M, R flags set.
    if (Node.isGlobalNode() && isGlobalsGraph) {
      ++NI;
      continue;
    }

    if (Node.isCompleteNode() && !Node.isModifiedNode() && !Node.isReadNode()) {
      // This is a useless node if it has no mod/ref info (checked above),
      // outgoing edges (which it cannot, as it is not modified in this
      // context), and it has no incoming edges.  If it is a global node it may
      // have all of these properties and still have incoming edges, due to the
      // scalar map, so we check those now.
      //
      if (Node.getNumReferrers() == Node.numGlobals()) {

        // Loop through and make sure all of the globals are referring directly
        // to the node...
        for (DSNode::globals_iterator j = Node.globals_begin(), e = Node.globals_end();
             j != e; ++j) {
          getNodeForValue(*j).getNode();
          assert((getNodeForValue(*j).getNode()) == &Node && "ScalarMap doesn't match globals list!");
        }

        // Make sure NumReferrers still agrees, if so, the node is truly dead.
        if (Node.getNumReferrers() == Node.numGlobals()) {
          for (DSNode::globals_iterator j = Node.globals_begin(), e = Node.globals_end();
               j != e; ++j)
            if (ScalarMap.find(*j) != ScalarMap.end())
              ScalarMap.erase(*j);
          Node.makeNodeDead();
          ++NumTrivialGlobalDNE;
        }
      }
    }

    if ((Node.getNodeFlags() == 0 && Node.hasNoReferrers())
        || (isGlobalsGraph && Node.hasNoReferrers() && !Node.isGlobalNode())){
      // This node is dead!
      NI = Nodes.erase(NI);    // Erase & remove from node list.
      ++NumTrivialDNE;
    } else {
      ++NI;
    }
  }
#if 0
#endif
  removeIdenticalCalls(FunctionCalls);
  removeIdenticalCalls(AuxFunctionCalls);
}

// CanReachAliveNodes - Simple graph walker that recursively traverses the graph
// looking for a node that is marked alive.  If an alive node is found, return
// true, otherwise return false.  If an alive node is reachable, this node is
// marked as alive...
//
static bool CanReachAliveNodes(DSNode *N, DenseSet<const DSNode*> &Alive,
                               DenseSet<const DSNode*> &Visited,
                               bool IgnoreGlobals) {
  if (N == 0) return false;
  assert(N->isForwarding() == 0 && "Cannot mark a forwarded node!");

  // If this is a global node, it will end up in the globals graph anyway, so we
  // don't need to worry about it.
  if (IgnoreGlobals && N->isGlobalNode()) return false;

  // If we know that this node is alive, return so!
  if (Alive.count(N)) return true;

  // Otherwise, we don't think the node is alive yet, check for infinite
  // recursion.
  if (Visited.count(N)) return false;  // Found a cycle
  Visited.insert(N);   // No recursion, insert into Visited...

  for (DSNode::edge_iterator I = N->edge_begin(),E = N->edge_end(); I != E; ++I)
    if (CanReachAliveNodes(I->second.getNode(), Alive, Visited, IgnoreGlobals)) {
      N->markReachableNodes(Alive);
      return true;
    }
  return false;
}

// CallSiteUsesAliveArgs - Return true if the specified call site can reach any
// alive nodes.
//
static bool CallSiteUsesAliveArgs(const DSCallSite &CS,
                                  DenseSet<const DSNode*> &Alive,
                                  DenseSet<const DSNode*> &Visited,
                                  bool IgnoreGlobals) {
  if (CanReachAliveNodes(CS.getRetVal().getNode(), Alive, Visited,
                         IgnoreGlobals))
    return true;
  if (CanReachAliveNodes(CS.getVAVal().getNode(), Alive, Visited, IgnoreGlobals))
    return true;
  if (CS.isIndirectCall() &&
      CanReachAliveNodes(CS.getCalleeNode(), Alive, Visited, IgnoreGlobals))
    return true;
  for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i)
    if (CanReachAliveNodes(CS.getPtrArg(i).getNode(), Alive, Visited,
                           IgnoreGlobals))
      return true;
  return false;
}

// removeDeadNodes - Use a more powerful reachability analysis to eliminate
// subgraphs that are unreachable.  This often occurs because the data
// structure doesn't "escape" into it's caller, and thus should be eliminated
// from the caller's graph entirely.  This is only appropriate to use when
// inlining graphs.
//
// This function also clones information about globals back into the globals
// graph before it deletes the nodes.
void DSGraph::removeDeadNodes(unsigned Flags) {
  DEBUG(AssertGraphOK(); if (GlobalsGraph) GlobalsGraph->AssertGraphOK());

  // Reduce the amount of work we have to do... remove dummy nodes left over by
  // merging...
  removeTriviallyDeadNodes();

  // FIXME: Merge non-trivially identical call nodes...

  // Alive - a set that holds all nodes found to be reachable/alive.
  DenseSet<const DSNode*> Alive;
  std::vector<std::pair<const Value*, DSNode*> > GlobalNodes;

  // Copy and merge all information about globals to the GlobalsGraph if this is
  // not a final pass (where unreachable globals are removed).
  //
  // Strip all alloca bits since we are merging information into the globals
  // graph.
  // Strip all incomplete bits since they are short-lived properties and they
  // will be correctly computed when rematerializing nodes into the functions.
  //
  // This code merges information learned about the globals in 'this' graph
  // back into the globals graph, before it deletes any such global nodes, 
  // (with some new information possibly) from 'this' current function graph.
  ReachabilityCloner GGCloner(GlobalsGraph, this, DSGraph::StripAllocaBit |
                              DSGraph::StripIncompleteBit);

  // Mark all nodes reachable by (non-global) scalar nodes as alive...
  for (DSScalarMap::iterator I = ScalarMap.begin(), E = ScalarMap.end();
          I != E; ++I)
    if (isa<GlobalValue > (I->first)) { // Keep track of global nodes
      assert(!I->second.isNull() && "Null global node?");
      assert(I->second.getNode()->isGlobalNode() && "Should be a global node!");
      GlobalNodes.push_back(std::make_pair(I->first, I->second.getNode()));

      // Make sure that all globals are cloned over as roots.
      if (!(Flags & DSGraph::RemoveUnreachableGlobals) && GlobalsGraph) {
          GGCloner.getClonedNH(I->second);
      }
    } else {
      I->second.getNode()->markReachableNodes(Alive);
    }

  // The return values are alive as well.
  for (ReturnNodesTy::iterator I = ReturnNodes.begin(), E = ReturnNodes.end();
       I != E; ++I)
    I->second.getNode()->markReachableNodes(Alive);

  // Mark any nodes reachable by primary calls as alive...
  for (fc_iterator I = fc_begin(), E = fc_end(); I != E; ++I)
    I->markReachableNodes(Alive);


  // Now find globals and aux call nodes that are already live or reach a live
  // value (which makes them live in turn), and continue till no more are found.
  //
  bool Iterate;
  DenseSet<const DSNode*> Visited;
  std::set<const DSCallSite*> AuxFCallsAlive;
  do {
    Visited.clear();
    // If any global node points to a non-global that is "alive", the global is
    // "alive" as well...  Remove it from the GlobalNodes list so we only have
    // unreachable globals in the list.
    //
    Iterate = false;
    if (!(Flags & DSGraph::RemoveUnreachableGlobals))
      for (unsigned i = 0; i != GlobalNodes.size(); ++i)
        if (CanReachAliveNodes(GlobalNodes[i].second, Alive, Visited,
                               Flags & DSGraph::RemoveUnreachableGlobals)) {
          std::swap(GlobalNodes[i--], GlobalNodes.back()); // Move to end to...
          GlobalNodes.pop_back();                          // erase efficiently
          Iterate = true;
        }

    // Mark only unresolvable call nodes for moving to the GlobalsGraph since
    // call nodes that get resolved will be difficult to remove from that graph.
    // The final unresolved call nodes must be handled specially at the end of
    // the BU pass (i.e., in main or other roots of the call graph).
    for (afc_iterator CI = afc_begin(), E = afc_end(); CI != E; ++CI)
      if (!AuxFCallsAlive.count(&*CI) &&
          (CI->isIndirectCall()
           || CallSiteUsesAliveArgs(*CI, Alive, Visited,
                                  Flags & DSGraph::RemoveUnreachableGlobals))) {
        CI->markReachableNodes(Alive);
        AuxFCallsAlive.insert(&*CI);
        Iterate = true;
      }
  } while (Iterate);

  // If only some of the aux calls are alive
  if (AuxFCallsAlive.size() != AuxFunctionCalls.size()) {
    // Move dead aux function calls to the end of the list
    FunctionListTy::iterator Erase = AuxFunctionCalls.end();
    for (FunctionListTy::iterator CI = AuxFunctionCalls.begin(); CI != Erase; )
      if (AuxFCallsAlive.count(&*CI))
        ++CI;
      else {
        // Copy and merge global nodes and dead aux call nodes into the
        // GlobalsGraph, and all nodes reachable from those nodes.  Update their
        // target pointers using the GGCloner.
        //
        if (!(Flags & DSGraph::RemoveUnreachableGlobals))
          GlobalsGraph->AuxFunctionCalls.push_back(DSCallSite(*CI, GGCloner));

        std::swap(*CI, *--Erase);
      }
    AuxFunctionCalls.erase(Erase, AuxFunctionCalls.end());
  }
  AuxFCallsAlive.clear();

  // We are finally done with the GGCloner so we can destroy it.
  GGCloner.destroy();

  // At this point, any nodes which are visited, but not alive, are nodes
  // which can be removed.  Loop over all nodes, eliminating completely
  // unreachable nodes.
  //
  std::vector<DSNode*> DeadNodes;
  DeadNodes.reserve(Nodes.size());
  for (NodeListTy::iterator NI = Nodes.begin(), E = Nodes.end(); NI != E;) {
    DSNode *N = NI++;
    assert(!N->isForwarding() && "Forwarded node in nodes list?");

    if (!Alive.count(N)) {
      Nodes.remove(N);
      assert(!N->isForwarding() && "Cannot remove a forwarding node!");
      DeadNodes.push_back(N);
      N->dropAllReferences();
      ++NumDNE;
    }
  }

  // Remove all unreachable globals from the ScalarMap.
  // If flag RemoveUnreachableGlobals is set, GlobalNodes has only dead nodes.
  // In either case, the dead nodes will not be in the set Alive.
  for (unsigned i = 0, e = GlobalNodes.size(); i != e; ++i)
    if (!Alive.count(GlobalNodes[i].second))
      ScalarMap.erase(GlobalNodes[i].first);
    else
      assert((Flags & DSGraph::RemoveUnreachableGlobals) && "non-dead global");

  // Delete all dead nodes now since their referrer counts are zero.
  for (unsigned i = 0, e = DeadNodes.size(); i != e; ++i)
    delete DeadNodes[i];

  DEBUG(AssertGraphOK(); GlobalsGraph->AssertGraphOK());
}

void DSGraph::AssertNodeContainsGlobal(const DSNode *N, const GlobalValue *GV) const {
  assert(std::find(N->globals_begin(),N->globals_end(), GV) !=
         N->globals_end() && "Global value not in node!");
}

void DSGraph::AssertCallSiteInGraph(const DSCallSite &CS) const {
  if (CS.isIndirectCall()) {
    AssertNodeInGraph(CS.getCalleeNode());
#if 0
    if (CS.getNumPtrArgs() && CS.getCalleeNode() == CS.getPtrArg(0).getNode() &&
        CS.getCalleeNode() && CS.getCalleeNode()->getGlobals().empty())
      DEBUG(errs() << "WARNING: WEIRD CALL SITE FOUND!\n");
#endif
  }
  AssertNodeInGraph(CS.getRetVal().getNode());
  AssertNodeInGraph(CS.getVAVal().getNode());
  for (unsigned j = 0, e = CS.getNumPtrArgs(); j != e; ++j)
    AssertNodeInGraph(CS.getPtrArg(j).getNode());
}

void DSGraph::AssertCallNodesInGraph() const {
  for (fc_iterator I = fc_begin(), E = fc_end(); I != E; ++I)
    AssertCallSiteInGraph(*I);
}
void DSGraph::AssertAuxCallNodesInGraph() const {
  for (afc_const_iterator I = afc_begin(), E = afc_end(); I != E; ++I)
    AssertCallSiteInGraph(*I);
}

void DSGraph::AssertGraphOK() const {
  for (node_const_iterator NI = node_begin(), E = node_end(); NI != E; ++NI)
    NI->assertOK();

  for (ScalarMapTy::const_iterator I = ScalarMap.begin(),
         E = ScalarMap.end(); I != E; ++I) {
    assert(!I->second.isNull() && "Null node in scalarmap!");
    AssertNodeInGraph(I->second.getNode());
    if (const GlobalValue *GV = dyn_cast<GlobalValue>(I->first)) {
      assert(I->second.getNode()->isGlobalNode() &&
             "Global points to node, but node isn't global?");
      AssertNodeContainsGlobal(I->second.getNode(), GV);
    }
  }
  AssertCallNodesInGraph();
  AssertAuxCallNodesInGraph();

  // Check that all pointer arguments to any functions in this graph have
  // destinations.
  for (ReturnNodesTy::const_iterator RI = ReturnNodes.begin(),
         E = ReturnNodes.end();
       RI != E; ++RI) {
    const Function &F = *RI->first;
    for (Function::const_arg_iterator AI = F.arg_begin(); AI != F.arg_end(); ++AI)
      if (isa<PointerType>(AI->getType()))
        assert(!getNodeForValue(AI).isNull() &&
               "Pointer argument must be in the scalar map!");
    if (F.isVarArg())
      assert(VANodes.find(&F) != VANodes.end() &&
          "VarArg function missing VANode!");
  }
}

/// computeNodeMapping - Given roots in two different DSGraphs, traverse the
/// nodes reachable from the two graphs, computing the mapping of nodes from the
/// first to the second graph.  This mapping may be many-to-one (i.e. the first
/// graph may have multiple nodes representing one node in the second graph),
/// but it will not work if there is a one-to-many or many-to-many mapping.
///
/// Inputs:
///   @NH1            - The first root value for which a node mapping is
///                     desired.  This value can have a NULL DSNode.
///   @NH2            - The second root value for which a node mapping is
///                     desired.  This value can have a NULL DSNode.
///   @StrictChecking - Flags whether strict sanity checks should be enforced.
///
/// Outputs:
///   @NodeMap - A mapping of DSNodes to DSNode handles providing the node
///              mapping desired by the caller.
///
/// Notes:
///   FIXME: Why was StrictChecking not passed in the recursive calls?
///   FIXME: Why isn't StrictChecking always desired?
///
void DSGraph::computeNodeMapping(const DSNodeHandle &NH1,
                                 const DSNodeHandle &NH2, NodeMapTy &NodeMap,
                                 bool StrictChecking) {
  //
  // Get the DSNodes associated with the root values.  If either one of them is
  // NULL, then we are done.
  //
  DSNode *N1 = NH1.getNode(), *N2 = NH2.getNode();
  if (N1 == 0 || N2 == 0) return;

  DSNodeHandle &Entry = NodeMap[N1];
  if (!Entry.isNull()) {
    // Termination of recursion!
    if (StrictChecking) {
      assert(Entry.getNode() == N2 && "Inconsistent mapping detected!");
      assert((Entry.getOffset() == (NH2.getOffset()-NH1.getOffset()) ||
              Entry.getNode()->isNodeCompletelyFolded()) &&
             "Inconsistent mapping detected!");
    }
    return;
  }

  //
  // Modify the entry in the node map so that the DSNode from the first
  // DSNodeHandle is mapped to the second DSNodeHandle.
  //
  // FIXME: AA:I am not sure what the right mapping for the
  // following case is. I believe we do not need to create any 
  // new mapping.
  //assert(((signed int)(NH2.getOffset()-NH1.getOffset())>=0) && " Underflow error ");
  if(NH2.getOffset() >= NH1.getOffset()) {
    Entry.setTo(N2, NH2.getOffset()-NH1.getOffset());
  }

  //
  // The two DSNodes that we have could be strucures with outgoing links to
  // other DSNodes.  Recursively map such outgoing edges together, too.
  //

  //
  // If the second DSNode has no outgoing edges, then stop processing.  There
  // is nothing more to do.
  //
  unsigned N2Size = N2->getSize();
  if (N2Size == 0) return;   // No edges to map to.

  //
  // Recursively link outgoing edges together.
  //
  int N2Idx = NH2.getOffset()-NH1.getOffset();
  for (unsigned i = 0, e = N1->getSize(); i < e; ++i) {
    const DSNodeHandle &N1NH = N1->getLink(i);
    //
    // Don't call N2->getLink if not needed (avoiding crash if N2Idx is not
    // aligned correctly).
    //
    if (!N1NH.isNull()) {
      //
      // Compute the offset into the second DSNode.
      //
      unsigned offset = 0;
      if (unsigned(N2Idx)+i < N2Size)
        offset = N2Idx+i;
      else
        offset = (unsigned(N2Idx+i) % N2Size);

      //
      // Compute the node mapping for the link.
      //
      computeNodeMapping (N1NH, N2->getLink(offset), NodeMap, StrictChecking);
    }
  }
}


/// computeGToGGMapping - Compute the mapping of nodes in the global graph to
/// nodes in this graph.
void DSGraph::computeGToGGMapping(NodeMapTy &NodeMap) {
  DSGraph &GG = *getGlobalsGraph();

  DSScalarMap &SM = getScalarMap();

  //
  // Iterate through all values used by this function (i.e., those values in
  // the local graph in the function's DSGraph).  For each one, compute the
  // mapping between its DSNode in the local graph and its DSNode in the
  // globals graph.
  //
  // Note that we use variables to hold intermediate values.  This allows us
  // to query these values more easily in the debugger.
  //
  for (DSScalarMap::global_iterator I = SM.global_begin(),
         E = SM.global_end(); I != E; ++I) {
    // Local value in the scalar map
    const Value * LocalValue = *I;

    // DSNode Handle for the value in the local graph
    DSNodeHandle LocalNodeHandle = SM[LocalValue];

    // DSNode Handle for the value in the globals graph
    DSNodeHandle GlobalNodeHandle = GG.getNodeForValue(LocalValue);

    //
    // Add to the node mapping the mapping between the DSNode in the local
    // graph and the DSNode in the globals graph.
    //
    DSGraph::computeNodeMapping(LocalNodeHandle, GlobalNodeHandle, NodeMap);
  }
}

/// computeGGToGMapping - Compute the mapping of nodes in the global graph to
/// nodes in this graph.  Note that any uses of this method are probably bugs,
/// unless it is known that the globals graph has been merged into this graph!
void DSGraph::computeGGToGMapping(InvNodeMapTy &InvNodeMap) {
  NodeMapTy NodeMap;
  computeGToGGMapping(NodeMap);

  while (!NodeMap.empty()) {
    InvNodeMap.insert(std::make_pair(NodeMap.begin()->second,
                                     NodeMap.begin()->first));
    NodeMap.erase(NodeMap.begin());
  }
}


/// computeCalleeCallerMapping - Given a call from a function in the current
/// graph to the 'Callee' function (which lives in 'CalleeGraph'), compute the
/// mapping of nodes from the callee to nodes in the caller.
void DSGraph::computeCalleeCallerMapping(DSCallSite CS, const Function &Callee,
                                         DSGraph &CalleeGraph,
                                         NodeMapTy &NodeMap) {

  DSCallSite CalleeArgs =
    CalleeGraph.getCallSiteForArguments(const_cast<Function&>(Callee));

  computeNodeMapping(CalleeArgs.getRetVal(), CS.getRetVal(), NodeMap);
  computeNodeMapping(CalleeArgs.getVAVal(), CS.getVAVal(), NodeMap);

  unsigned NumArgs = CS.getNumPtrArgs();
  if (NumArgs > CalleeArgs.getNumPtrArgs())
    NumArgs = CalleeArgs.getNumPtrArgs();

  for (unsigned i = 0; i != NumArgs; ++i)
    computeNodeMapping(CalleeArgs.getPtrArg(i), CS.getPtrArg(i), NodeMap);

  // Map the nodes that are pointed to by globals.
  DSScalarMap &CalleeSM = CalleeGraph.getScalarMap();
  DSScalarMap &CallerSM = getScalarMap();

  if (CalleeSM.global_size() >= CallerSM.global_size()) {
    for (DSScalarMap::global_iterator GI = CallerSM.global_begin(),
           E = CallerSM.global_end(); GI != E; ++GI)
      if (CalleeSM.global_count(*GI))
        computeNodeMapping(CalleeSM[*GI], CallerSM[*GI], NodeMap);
  } else {
    for (DSScalarMap::global_iterator GI = CalleeSM.global_begin(),
           E = CalleeSM.global_end(); GI != E; ++GI)
      if (CallerSM.global_count(*GI))
        computeNodeMapping(CalleeSM[*GI], CallerSM[*GI], NodeMap);
  }
}

/// updateFromGlobalGraph - This function rematerializes global nodes and
/// nodes reachable from them from the globals graph into the current graph.
///
void DSGraph::updateFromGlobalGraph() {
  ReachabilityCloner RC(this, GlobalsGraph, 0);

  // Clone the non-up-to-date global nodes into this graph.
  for (DSScalarMap::global_iterator I = getScalarMap().global_begin(),
         E = getScalarMap().global_end(); I != E; ++I) {
    DSScalarMap::iterator It = GlobalsGraph->ScalarMap.find(*I);
    if (It != GlobalsGraph->ScalarMap.end())
      RC.merge(getNodeForValue(*I), It->second);
  }
}

//
// Function: functionIsCallable()
//
// Description:
//  Determine whether the specified function can be a target of the specified
//  call site.  We allow the user to configure what we consider to be
//  uncallable at an indirect function call site.
//
// Inputs:
//  CS - The call site which calls the function.
//  F  - The function that is potentially called by CS.
//
// Return value:
//  true  - The function F can be called by the call site.
//  false - The function F cannot be called by the call site.
//
bool
llvm::functionIsCallable (ImmutableCallSite CS, const Function* F) {
  //Which targets do we choose?
  //Conservative: all of them
  //Pretty Safe: same calling convention, otherwise undefined behavior
  //Safe on some archs:
  //Safe?: vararg call only calling vararg functions
  //Safe?: non-vararg call only calling non-vararg functions
  //Safe?: iany/ptr can't be interchanged in args w/ float/double
  //Not so safe: number of args matching
  const PointerType*  PT = cast<PointerType>(CS.getCalledValue()->getType());
  const FunctionType* FT = cast<FunctionType>(PT->getElementType());

  //
  // If the calling convention doesn't match, then the function cannot be
  // called by this call site.
  //
  if (!noDSACallConv && CS.getCallingConv() != F->getCallingConv())
    return false;

  //
  // We will consider the byval parameter attribute to be a part of the calling
  // convention.  If an actual argument is marked byval while the formal
  // argument is not (or vice-versa), then the function is not a valid target.
  //
  if (!noDSACallConv) {
    Function::const_arg_iterator farg = F->arg_begin(), fend = F->arg_end();
    for (unsigned index = 1; index < (CS.arg_size() + 1) && farg != fend;
        ++farg, ++index) {
      if (CS.isByValArgument(index) != farg->hasByValAttr()) {
        return false;
      }
    }
  }

  //
  // If the caller and callee don't agree on whether the target is a vararg
  // function, then the function is not a valid target.
  //
  if (!noDSACallVA && FT->isVarArg() != F->isVarArg())
    return false;

  //
  // If calling this function from this call site would require an implicit
  // integer to floating point cast (or vice-versa), then don't consider the
  // function callable from this call site.
  //
  if (!noDSACallFP) {
    unsigned ANumParams = F->getFunctionType()->getNumParams();
    unsigned PNumParams = FT->getNumParams();
    unsigned NumParams = (ANumParams < PNumParams) ? ANumParams : PNumParams;
    for (unsigned index = 0; index < NumParams; ++index) {
      Type * AType = F->getFunctionType()->getParamType(index);
      Type * PType = FT->getParamType(index);
      if ((AType->isFPOrFPVectorTy() && !PType->isFPOrFPVectorTy())
          ||
          (!AType->isFPOrFPVectorTy() && PType->isFPOrFPVectorTy()))
        return false;
    }
  }
  
  if (!noDSACallNumArgs) {
    if(CS.arg_size() < F->arg_size()) {
      return false;
    }
  }

  //
  // We've done all the checks we've cared to do.  The function F can be called
  // from this call site.
  //
  return true;
}

//
// Method: buildCallGraph()
//
// Description:
//  This method updates the given call graph with new information about targets
//  of function calls that can be inferred from the unresolved call sites
//  within the DSGraph.
//
//  The parameter GlobalFunctionList, is a list of all the address taken 
//  functions in the module. This is used as the list of targets when a callee
//  node is Incomplete.
//
//  The parameter 'filter' determines if we should attempt to prune callees
//  that are illegal to be called from the callsite.
//
void DSGraph::buildCallGraph(DSCallGraph& DCG, std::vector<const Function*>& GlobalFunctionList, bool filter) const {
  //
  // Get the list of unresolved call sites.
  //
  const FunctionListTy& Calls = getFunctionCalls();
  for (FunctionListTy::const_iterator ii = Calls.begin(),
      ee = Calls.end();
      ii != ee; ++ii) {
    //
    // Direct calls are easy.  We know to where they go.
    //

    if (ii->isDirectCall()) {
      DCG.insert(ii->getCallSite(), ii->getCalleeFunc());
    } else {
      CallSite CS = ii->getCallSite();
      std::vector<const Function*> MaybeTargets;

      if(ii->getCalleeNode()->isIncompleteNode())
        continue;
      //
      // Get the list of known targets of this function.
      //
      ii->getCalleeNode()->addFullFunctionList(MaybeTargets);

      //
      // Ensure that the call graph at least knows about (has a record of) this
      //  call site.
      //
      DCG.insert(CS, 0);

      //
      // Add to the call graph only function targets that have well-defined
      // behavior using LLVM semantics.
      //
      for (std::vector<const Function*>::iterator Fi = MaybeTargets.begin(),
           Fe = MaybeTargets.end(); Fi != Fe; ++Fi)
        if (!filter || functionIsCallable(CS, *Fi))
          DCG.insert(CS, *Fi);
        else
          ++NumFiltered;
      for (DSCallSite::MappedSites_t::iterator I = ii->ms_begin(),
           E = ii->ms_end(); I != E; ++I) {
        CallSite MCS = *I;
        for (std::vector<const Function*>::iterator Fi = MaybeTargets.begin(),
             Fe = MaybeTargets.end(); Fi != Fe; ++Fi)
          if (!filter || functionIsCallable(MCS, *Fi))
            DCG.insert(MCS, *Fi);
          else
            ++NumFiltered;
      }
    }
  }
}

void DSGraph::buildCompleteCallGraph(DSCallGraph& DCG, 
                                     std::vector<const Function*>& GlobalFunctionList, bool filter) const {
  //
  // Get the list of unresolved call sites.
  //
  const FunctionListTy& Calls = getAuxFunctionCalls();
  for (FunctionListTy::const_iterator ii = Calls.begin(),
                                             ee = Calls.end();
       ii != ee; ++ii) {

    if (ii->isDirectCall()) continue;
    CallSite CS = ii->getCallSite();
    if (DCG.callee_size(CS) != 0) continue;
    std::vector<const Function*> MaybeTargets;
    MaybeTargets.assign(GlobalFunctionList.begin(), GlobalFunctionList.end());

    DCG.insert(CS, 0);
    //
    // Add to the call graph only function targets that have well-defined
    // behavior using LLVM semantics.
    //
    for (std::vector<const Function*>::iterator Fi = MaybeTargets.begin(),
         Fe = MaybeTargets.end(); Fi != Fe; ++Fi)
      if (!filter || functionIsCallable(CS, *Fi))
        DCG.insert(CS, *Fi);
      else
        ++NumFiltered;

    for (DSCallSite::MappedSites_t::iterator I = ii->ms_begin(),
         E = ii->ms_end(); I != E; ++I) {
      CallSite MCS = *I;
      for (std::vector<const Function*>::iterator Fi = MaybeTargets.begin(),
           Fe = MaybeTargets.end(); Fi != Fe; ++Fi) {
        if (!filter || functionIsCallable(MCS, *Fi))
          DCG.insert(MCS, *Fi);
        else
          ++NumFiltered;
      }
    }
  }
  svset<const llvm::Function*> callees;
  callees.insert(GlobalFunctionList.begin(), GlobalFunctionList.end());
  DCG.buildIncompleteCalleeSet(callees);
}