poolalloc/lib/DSA/EquivClassGraphs.cpp - llvm-archive - Git at Google

 //===- EquivClassGraphs.cpp - Merge equiv-class graphs & inline bottom-up -===//
 //
 //                     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 pass is the same as the complete bottom-up graphs, but
 // with functions partitioned into equivalence classes and a single merged
 // DS graph for all functions in an equivalence class.  After this merging,
 // graphs are inlined bottom-up on the SCCs of the final (CBU) call graph.
 //
 //===----------------------------------------------------------------------===//

 #define DEBUG_TYPE "ECGraphs"
 #include "llvm/Analysis/DataStructure/DataStructure.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Analysis/DataStructure/DSGraph.h"
 #include "llvm/Support/CallSite.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/ADT/SCCIterator.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/EquivalenceClasses.h"
 #include "llvm/ADT/STLExtras.h"
 using namespace llvm;

 namespace {
   RegisterAnalysis<EquivClassGraphs> X("eqdatastructure",
                     "Equivalence-class Bottom-up Data Structure Analysis");
   Statistic<> NumEquivBUInlines("equivdatastructures",
                                 "Number of graphs inlined");
   Statistic<> NumFoldGraphInlines("Inline equiv-class graphs bottom up",
                                   "Number of graphs inlined");
 }

 #ifndef NDEBUG
 template<typename GT>
 static void CheckAllGraphs(Module *M, GT &ECGraphs) {
   DSGraph &GG = ECGraphs.getGlobalsGraph();

   for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
     if (!I->isExternal()) {
       DSGraph &G = ECGraphs.getDSGraph(*I);
       if (G.retnodes_begin()->first != I)
         continue;  // Only check a graph once.

       DSGraph::NodeMapTy GlobalsGraphNodeMapping;
       G.computeGToGGMapping(GlobalsGraphNodeMapping);
     }
 }
 #endif

 // getSomeCalleeForCallSite - Return any one callee function at a call site.
 //
 Function *EquivClassGraphs::getSomeCalleeForCallSite(const CallSite &CS) const{
   Function *thisFunc = CS.getCaller();
   assert(thisFunc && "getSomeCalleeForCallSite(): Not a valid call site?");
   DSGraph &DSG = getDSGraph(*thisFunc);
   DSNode *calleeNode = DSG.getNodeForValue(CS.getCalledValue()).getNode();
   std::map<DSNode*, Function *>::const_iterator I =
     OneCalledFunction.find(calleeNode);
   return (I == OneCalledFunction.end())? NULL : I->second;
 }

 // runOnModule - Calculate the bottom up data structure graphs for each function
 // in the program.
 //
 bool EquivClassGraphs::runOnModule(Module &M) {
   CBU = &getAnalysis<CompleteBUDataStructures>();
   GlobalECs = CBU->getGlobalECs();
   DEBUG(CheckAllGraphs(&M, *CBU));

   GlobalsGraph = new DSGraph(CBU->getGlobalsGraph(), GlobalECs);
   GlobalsGraph->setPrintAuxCalls();

   ActualCallees = CBU->getActualCallees();

   // Find equivalence classes of functions called from common call sites.
   // Fold the CBU graphs for all functions in an equivalence class.
   buildIndirectFunctionSets(M);

   // Stack of functions used for Tarjan's SCC-finding algorithm.
   std::vector<DSGraph*> Stack;
   std::map<DSGraph*, unsigned> ValMap;
   unsigned NextID = 1;

   Function *MainFunc = M.getMainFunction();
   if (MainFunc && !MainFunc->isExternal()) {
     processSCC(getOrCreateGraph(*MainFunc), Stack, NextID, ValMap);
   } else {
     std::cerr << "Fold Graphs: No 'main' function found!\n";
   }

   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
     if (!I->isExternal())
       processSCC(getOrCreateGraph(*I), Stack, NextID, ValMap);

   DEBUG(CheckAllGraphs(&M, *this));

   getGlobalsGraph().removeTriviallyDeadNodes();
   getGlobalsGraph().markIncompleteNodes(DSGraph::IgnoreGlobals);

   // Merge the globals variables (not the calls) from the globals graph back
   // into the main function's graph so that the main function contains all of
   // the information about global pools and GV usage in the program.
   if (MainFunc && !MainFunc->isExternal()) {
     DSGraph &MainGraph = getOrCreateGraph(*MainFunc);
     const DSGraph &GG = *MainGraph.getGlobalsGraph();
     ReachabilityCloner RC(MainGraph, GG,
                           DSGraph::DontCloneCallNodes |
                           DSGraph::DontCloneAuxCallNodes);

     // Clone the global nodes into this graph.
     for (DSScalarMap::global_iterator I = GG.getScalarMap().global_begin(),
            E = GG.getScalarMap().global_end(); I != E; ++I)
       if (isa<GlobalVariable>(*I))
         RC.getClonedNH(GG.getNodeForValue(*I));

     MainGraph.maskIncompleteMarkers();
     MainGraph.markIncompleteNodes(DSGraph::MarkFormalArgs |
                                   DSGraph::IgnoreGlobals);
   }

   // Final processing.  Note that dead node elimination may actually remove
   // globals from a function graph that are immediately used.  If there are no
   // scalars pointing to the node (e.g. because the only use is a direct store
   // to a scalar global) we have to make sure to rematerialize the globals back
   // into the graphs here, or clients will break!
   for (Module::global_iterator GI = M.global_begin(), E = M.global_end();
        GI != E; ++GI)
     // This only happens to first class typed globals.
     if (GI->getType()->getElementType()->isFirstClassType())
       for (Value::use_iterator UI = GI->use_begin(), E = GI->use_end();
            UI != E; ++UI)
         // This only happens to direct uses by instructions.
         if (Instruction *User = dyn_cast<Instruction>(*UI)) {
           DSGraph &DSG = getOrCreateGraph(*User->getParent()->getParent());
           if (!DSG.getScalarMap().count(GI)) {
             // If this global does not exist in the graph, but it is immediately
             // used by an instruction in the graph, clone it over from the
             // globals graph.
             ReachabilityCloner RC(DSG, *GlobalsGraph, 0);
             RC.getClonedNH(GlobalsGraph->getNodeForValue(GI));
           }
         }

   return false;
 }


 // buildIndirectFunctionSets - Iterate over the module looking for indirect
 // calls to functions.  If a call site can invoke any functions [F1, F2... FN],
 // unify the N functions together in the FuncECs set.
 //
 void EquivClassGraphs::buildIndirectFunctionSets(Module &M) {
   const ActualCalleesTy& AC = CBU->getActualCallees();

   // Loop over all of the indirect calls in the program.  If a call site can
   // call multiple different functions, we need to unify all of the callees into
   // the same equivalence class.
   Instruction *LastInst = 0;
   Function *FirstFunc = 0;
   for (ActualCalleesTy::const_iterator I=AC.begin(), E=AC.end(); I != E; ++I) {
     if (I->second->isExternal())
       continue;                         // Ignore functions we cannot modify

     CallSite CS = CallSite::get(I->first);

     if (CS.getCalledFunction()) {       // Direct call:
       FuncECs.insert(I->second);        // -- Make sure function has equiv class
       FirstFunc = I->second;            // -- First callee at this site
     } else {                            // Else indirect call
       // DEBUG(std::cerr << "CALLEE: " << I->second->getName()
       //       << " from : " << I->first);
       if (I->first != LastInst) {
         // This is the first callee from this call site.
         LastInst = I->first;
         FirstFunc = I->second;
         // Instead of storing the lastInst For Indirection call Sites we store
         // the DSNode for the function ptr arguemnt
         Function *thisFunc = LastInst->getParent()->getParent();
         DSGraph &TFG = CBU->getDSGraph(*thisFunc);
         DSNode *calleeNode = TFG.getNodeForValue(CS.getCalledValue()).getNode();
         OneCalledFunction[calleeNode] = FirstFunc;
         FuncECs.insert(I->second);
       } else {
         // This is not the first possible callee from a particular call site.
         // Union the callee in with the other functions.
         FuncECs.unionSets(FirstFunc, I->second);
 #ifndef NDEBUG
         Function *thisFunc = LastInst->getParent()->getParent();
         DSGraph &TFG = CBU->getDSGraph(*thisFunc);
         DSNode *calleeNode = TFG.getNodeForValue(CS.getCalledValue()).getNode();
         assert(OneCalledFunction.count(calleeNode) > 0 && "Missed a call?");
 #endif
       }
     }

     // Now include all functions that share a graph with any function in the
     // equivalence class.  More precisely, if F is in the class, and G(F) is
     // its graph, then we include all other functions that are also in G(F).
     // Currently, that is just the functions in the same call-graph-SCC as F.
     //
     DSGraph& funcDSGraph = CBU->getDSGraph(*I->second);
     for (DSGraph::retnodes_iterator RI = funcDSGraph.retnodes_begin(),
            RE = funcDSGraph.retnodes_end(); RI != RE; ++RI)
       FuncECs.unionSets(FirstFunc, RI->first);
   }

   // Now that all of the equivalences have been built, merge the graphs for
   // each equivalence class.
   //
   DEBUG(std::cerr << "\nIndirect Function Equivalence Sets:\n");
   for (EquivalenceClasses<Function*>::iterator EQSI = FuncECs.begin(), E =
          FuncECs.end(); EQSI != E; ++EQSI) {
     if (!EQSI->isLeader()) continue;

     EquivalenceClasses<Function*>::member_iterator SI =
       FuncECs.member_begin(EQSI);
     assert(SI != FuncECs.member_end() && "Empty equiv set??");
     EquivalenceClasses<Function*>::member_iterator SN = SI;
     ++SN;
     if (SN == FuncECs.member_end())
       continue;   // Single function equivalence set, no merging to do.

     Function* LF = *SI;

 #ifndef NDEBUG
     DEBUG(std::cerr <<"  Equivalence set for leader " << LF->getName() <<" = ");
     for (SN = SI; SN != FuncECs.member_end(); ++SN)
       DEBUG(std::cerr << " " << (*SN)->getName() << "," );
     DEBUG(std::cerr << "\n");
 #endif

     // This equiv class has multiple functions: merge their graphs.  First,
     // clone the CBU graph for the leader and make it the common graph for the
     // equivalence graph.
     DSGraph &MergedG = getOrCreateGraph(*LF);

     // Record the argument nodes for use in merging later below.
     std::vector<DSNodeHandle> ArgNodes;

     for (Function::arg_iterator AI = LF->arg_begin(), E = LF->arg_end();
          AI != E; ++AI)
       if (DS::isPointerType(AI->getType()))
         ArgNodes.push_back(MergedG.getNodeForValue(AI));

     // Merge in the graphs of all other functions in this equiv. class.  Note
     // that two or more functions may have the same graph, and it only needs
     // to be merged in once.
     std::set<DSGraph*> GraphsMerged;
     GraphsMerged.insert(&CBU->getDSGraph(*LF));

     for (++SI; SI != FuncECs.member_end(); ++SI) {
       Function *F = *SI;
       DSGraph *&FG = DSInfo[F];

       DSGraph &CBUGraph = CBU->getDSGraph(*F);
       if (GraphsMerged.insert(&CBUGraph).second) {
         // Record the "folded" graph for the function.
         for (DSGraph::retnodes_iterator I = CBUGraph.retnodes_begin(),
                E = CBUGraph.retnodes_end(); I != E; ++I) {
           assert(DSInfo[I->first] == 0 && "Graph already exists for Fn!");
           DSInfo[I->first] = &MergedG;
         }

         // Clone this member of the equivalence class into MergedG.
         MergedG.cloneInto(CBUGraph);
       }

       // Merge the return nodes of all functions together.
       MergedG.getReturnNodes()[LF].mergeWith(MergedG.getReturnNodes()[F]);

       // Merge the function arguments with all argument nodes found so far.
       // If there are extra function args, add them to the vector of argNodes
       Function::arg_iterator AI2 = F->arg_begin(), AI2end = F->arg_end();
       for (unsigned arg = 0, numArgs = ArgNodes.size();
            arg != numArgs && AI2 != AI2end; ++AI2, ++arg)
         if (DS::isPointerType(AI2->getType()))
           ArgNodes[arg].mergeWith(MergedG.getNodeForValue(AI2));

       for ( ; AI2 != AI2end; ++AI2)
         if (DS::isPointerType(AI2->getType()))
           ArgNodes.push_back(MergedG.getNodeForValue(AI2));
       DEBUG(MergedG.AssertGraphOK());
     }
   }
   DEBUG(std::cerr << "\n");
 }


 DSGraph &EquivClassGraphs::getOrCreateGraph(Function &F) {
   // Has the graph already been created?
   DSGraph *&Graph = DSInfo[&F];
   if (Graph) return *Graph;

   DSGraph &CBUGraph = CBU->getDSGraph(F);

   // Copy the CBU graph...
   Graph = new DSGraph(CBUGraph, GlobalECs);   // updates the map via reference
   Graph->setGlobalsGraph(&getGlobalsGraph());
   Graph->setPrintAuxCalls();

   // Make sure to update the DSInfo map for all functions in the graph!
   for (DSGraph::retnodes_iterator I = Graph->retnodes_begin();
        I != Graph->retnodes_end(); ++I)
     if (I->first != &F) {
       DSGraph *&FG = DSInfo[I->first];
       assert(FG == 0 && "Merging function in SCC twice?");
       FG = Graph;
     }

   return *Graph;
 }


 unsigned EquivClassGraphs::
 processSCC(DSGraph &FG, std::vector<DSGraph*> &Stack, unsigned &NextID,
            std::map<DSGraph*, unsigned> &ValMap) {
   std::map<DSGraph*, unsigned>::iterator It = ValMap.lower_bound(&FG);
   if (It != ValMap.end() && It->first == &FG)
     return It->second;

   DEBUG(std::cerr << "    ProcessSCC for function " << FG.getFunctionNames()
                   << "\n");

   unsigned Min = NextID++, MyID = Min;
   ValMap[&FG] = Min;
   Stack.push_back(&FG);

   // The edges out of the current node are the call site targets...
   for (DSGraph::fc_iterator CI = FG.fc_begin(), CE = FG.fc_end();
        CI != CE; ++CI) {
     Instruction *Call = CI->getCallSite().getInstruction();

     // Loop over all of the actually called functions...
     for (callee_iterator I = callee_begin(Call), E = callee_end(Call);
          I != E; ++I)
       if (!I->second->isExternal()) {
         // Process the callee as necessary.
         unsigned M = processSCC(getOrCreateGraph(*I->second),
                                 Stack, NextID, ValMap);
         if (M < Min) Min = M;
       }
   }

   assert(ValMap[&FG] == MyID && "SCC construction assumption wrong!");
   if (Min != MyID)
     return Min;         // This is part of a larger SCC!

   // If this is a new SCC, process it now.
   bool MergedGraphs = false;
   while (Stack.back() != &FG) {
     DSGraph *NG = Stack.back();
     ValMap[NG] = ~0U;

     // If the SCC found is not the same as those found in CBU, make sure to
     // merge the graphs as appropriate.
     FG.cloneInto(*NG);

     // Update the DSInfo map and delete the old graph...
     for (DSGraph::retnodes_iterator I = NG->retnodes_begin();
          I != NG->retnodes_end(); ++I)
       DSInfo[I->first] = &FG;

     // Remove NG from the ValMap since the pointer may get recycled.
     ValMap.erase(NG);
     delete NG;
     MergedGraphs = true;
     Stack.pop_back();
   }

   // Clean up the graph before we start inlining a bunch again.
   if (MergedGraphs)
     FG.removeTriviallyDeadNodes();

   Stack.pop_back();

   processGraph(FG);
   ValMap[&FG] = ~0U;
   return MyID;
 }


 /// processGraph - Process the CBU graphs for the program in bottom-up order on
 /// the SCC of the __ACTUAL__ call graph.  This builds final folded CBU graphs.
 void EquivClassGraphs::processGraph(DSGraph &G) {
   DEBUG(std::cerr << "    ProcessGraph for function "
                   << G.getFunctionNames() << "\n");

   hash_set<Instruction*> calls;

   // Else we need to inline some callee graph.  Visit all call sites.
   // The edges out of the current node are the call site targets...
   unsigned i = 0;
   for (DSGraph::fc_iterator CI = G.fc_begin(), CE = G.fc_end(); CI != CE;
        ++CI, ++i) {
     const DSCallSite &CS = *CI;
     Instruction *TheCall = CS.getCallSite().getInstruction();

     assert(calls.insert(TheCall).second &&
            "Call instruction occurs multiple times in graph??");

     if (CS.getRetVal().isNull() && CS.getNumPtrArgs() == 0)
       continue;

     // Inline the common callee graph into the current graph, if the callee
     // graph has not changed.  Note that all callees should have the same
     // graph so we only need to do this once.
     //
     DSGraph* CalleeGraph = NULL;
     callee_iterator I = callee_begin(TheCall), E = callee_end(TheCall);
     unsigned TNum, Num;

     // Loop over all potential callees to find the first non-external callee.
     for (TNum = 0, Num = std::distance(I, E); I != E; ++I, ++TNum)
       if (!I->second->isExternal())
         break;

     // Now check if the graph has changed and if so, clone and inline it.
     if (I != E) {
       Function *CalleeFunc = I->second;

       // Merge the callee's graph into this graph, if not already the same.
       // Callees in the same equivalence class (which subsumes those
       // in the same SCCs) have the same graph.  Note that all recursion
       // including self-recursion have been folded in the equiv classes.
       //
       CalleeGraph = &getOrCreateGraph(*CalleeFunc);
       if (CalleeGraph != &G) {
         ++NumFoldGraphInlines;
         G.mergeInGraph(CS, *CalleeFunc, *CalleeGraph,
                        DSGraph::StripAllocaBit |
                        DSGraph::DontCloneCallNodes |
                        DSGraph::DontCloneAuxCallNodes);
         DEBUG(std::cerr << "    Inlining graph [" << i << "/"
               << G.getFunctionCalls().size()-1
               << ":" << TNum << "/" << Num-1 << "] for "
               << CalleeFunc->getName() << "["
               << CalleeGraph->getGraphSize() << "+"
               << CalleeGraph->getAuxFunctionCalls().size()
               << "] into '" /*<< G.getFunctionNames()*/ << "' ["
               << G.getGraphSize() << "+" << G.getAuxFunctionCalls().size()
               << "]\n");
       }
     }

 #ifndef NDEBUG
     // Now loop over the rest of the callees and make sure they have the
     // same graph as the one inlined above.
     if (CalleeGraph)
       for (++I, ++TNum; I != E; ++I, ++TNum)
         if (!I->second->isExternal())
           assert(CalleeGraph == &getOrCreateGraph(*I->second) &&
                  "Callees at a call site have different graphs?");
 #endif
   }

   // Recompute the Incomplete markers.
   G.maskIncompleteMarkers();
   G.markIncompleteNodes(DSGraph::MarkFormalArgs);

   // Delete dead nodes.  Treat globals that are unreachable but that can
   // reach live nodes as live.
   G.removeDeadNodes(DSGraph::KeepUnreachableGlobals);

   // When this graph is finalized, clone the globals in the graph into the
   // globals graph to make sure it has everything, from all graphs.
   ReachabilityCloner RC(*G.getGlobalsGraph(), G, DSGraph::StripAllocaBit);

   // Clone everything reachable from globals in the function graph into the
   // globals graph.
   DSScalarMap &MainSM = G.getScalarMap();
   for (DSScalarMap::global_iterator I = MainSM.global_begin(),
          E = MainSM.global_end(); I != E; ++I)
     RC.getClonedNH(MainSM[*I]);

   DEBUG(std::cerr << "  -- DONE ProcessGraph for function "
                   << G.getFunctionNames() << "\n");
 }
	//===- EquivClassGraphs.cpp - Merge equiv-class graphs & inline bottom-up -===//
	//
	// 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 pass is the same as the complete bottom-up graphs, but
	// with functions partitioned into equivalence classes and a single merged
	// DS graph for all functions in an equivalence class. After this merging,
	// graphs are inlined bottom-up on the SCCs of the final (CBU) call graph.
	//
	//===----------------------------------------------------------------------===//

	#define DEBUG_TYPE "ECGraphs"
	#include "llvm/Analysis/DataStructure/DataStructure.h"
	#include "llvm/DerivedTypes.h"
	#include "llvm/Module.h"
	#include "llvm/Pass.h"
	#include "llvm/Analysis/DataStructure/DSGraph.h"
	#include "llvm/Support/CallSite.h"
	#include "llvm/Support/Debug.h"
	#include "llvm/ADT/SCCIterator.h"
	#include "llvm/ADT/Statistic.h"
	#include "llvm/ADT/EquivalenceClasses.h"
	#include "llvm/ADT/STLExtras.h"
	using namespace llvm;

	namespace {
	RegisterAnalysis<EquivClassGraphs> X("eqdatastructure",
	"Equivalence-class Bottom-up Data Structure Analysis");
	Statistic<> NumEquivBUInlines("equivdatastructures",
	"Number of graphs inlined");
	Statistic<> NumFoldGraphInlines("Inline equiv-class graphs bottom up",
	"Number of graphs inlined");
	}

	#ifndef NDEBUG
	template<typename GT>
	static void CheckAllGraphs(Module *M, GT &ECGraphs) {
	DSGraph &GG = ECGraphs.getGlobalsGraph();

	for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
	if (!I->isExternal()) {
	DSGraph &G = ECGraphs.getDSGraph(*I);
	if (G.retnodes_begin()->first != I)
	continue; // Only check a graph once.

	DSGraph::NodeMapTy GlobalsGraphNodeMapping;
	G.computeGToGGMapping(GlobalsGraphNodeMapping);
	}
	}
	#endif

	// getSomeCalleeForCallSite - Return any one callee function at a call site.
	//
	Function *EquivClassGraphs::getSomeCalleeForCallSite(const CallSite &CS) const{
	Function *thisFunc = CS.getCaller();
	assert(thisFunc && "getSomeCalleeForCallSite(): Not a valid call site?");
	DSGraph &DSG = getDSGraph(*thisFunc);
	DSNode *calleeNode = DSG.getNodeForValue(CS.getCalledValue()).getNode();
	std::map<DSNode, Function >::const_iterator I =
	OneCalledFunction.find(calleeNode);
	return (I == OneCalledFunction.end())? NULL : I->second;
	}

	// runOnModule - Calculate the bottom up data structure graphs for each function
	// in the program.
	//
	bool EquivClassGraphs::runOnModule(Module &M) {
	CBU = &getAnalysis<CompleteBUDataStructures>();
	GlobalECs = CBU->getGlobalECs();
	DEBUG(CheckAllGraphs(&M, *CBU));

	GlobalsGraph = new DSGraph(CBU->getGlobalsGraph(), GlobalECs);
	GlobalsGraph->setPrintAuxCalls();

	ActualCallees = CBU->getActualCallees();

	// Find equivalence classes of functions called from common call sites.
	// Fold the CBU graphs for all functions in an equivalence class.
	buildIndirectFunctionSets(M);

	// Stack of functions used for Tarjan's SCC-finding algorithm.
	std::vector<DSGraph*> Stack;
	std::map<DSGraph*, unsigned> ValMap;
	unsigned NextID = 1;

	Function *MainFunc = M.getMainFunction();
	if (MainFunc && !MainFunc->isExternal()) {
	processSCC(getOrCreateGraph(*MainFunc), Stack, NextID, ValMap);
	} else {
	std::cerr << "Fold Graphs: No 'main' function found!\n";
	}

	for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
	if (!I->isExternal())
	processSCC(getOrCreateGraph(*I), Stack, NextID, ValMap);

	DEBUG(CheckAllGraphs(&M, *this));

	getGlobalsGraph().removeTriviallyDeadNodes();
	getGlobalsGraph().markIncompleteNodes(DSGraph::IgnoreGlobals);

	// Merge the globals variables (not the calls) from the globals graph back
	// into the main function's graph so that the main function contains all of
	// the information about global pools and GV usage in the program.
	if (MainFunc && !MainFunc->isExternal()) {
	DSGraph &MainGraph = getOrCreateGraph(*MainFunc);
	const DSGraph &GG = *MainGraph.getGlobalsGraph();
	ReachabilityCloner RC(MainGraph, GG,
	DSGraph::DontCloneCallNodes \|
	DSGraph::DontCloneAuxCallNodes);

	// Clone the global nodes into this graph.
	for (DSScalarMap::global_iterator I = GG.getScalarMap().global_begin(),
	E = GG.getScalarMap().global_end(); I != E; ++I)
	if (isa<GlobalVariable>(*I))
	RC.getClonedNH(GG.getNodeForValue(*I));

	MainGraph.maskIncompleteMarkers();
	MainGraph.markIncompleteNodes(DSGraph::MarkFormalArgs \|
	DSGraph::IgnoreGlobals);
	}

	// Final processing. Note that dead node elimination may actually remove
	// globals from a function graph that are immediately used. If there are no
	// scalars pointing to the node (e.g. because the only use is a direct store
	// to a scalar global) we have to make sure to rematerialize the globals back
	// into the graphs here, or clients will break!
	for (Module::global_iterator GI = M.global_begin(), E = M.global_end();
	GI != E; ++GI)
	// This only happens to first class typed globals.
	if (GI->getType()->getElementType()->isFirstClassType())
	for (Value::use_iterator UI = GI->use_begin(), E = GI->use_end();
	UI != E; ++UI)
	// This only happens to direct uses by instructions.
	if (Instruction User = dyn_cast<Instruction>(UI)) {
	DSGraph &DSG = getOrCreateGraph(*User->getParent()->getParent());
	if (!DSG.getScalarMap().count(GI)) {
	// If this global does not exist in the graph, but it is immediately
	// used by an instruction in the graph, clone it over from the
	// globals graph.
	ReachabilityCloner RC(DSG, *GlobalsGraph, 0);
	RC.getClonedNH(GlobalsGraph->getNodeForValue(GI));
	}
	}

	return false;
	}


	// buildIndirectFunctionSets - Iterate over the module looking for indirect
	// calls to functions. If a call site can invoke any functions [F1, F2... FN],
	// unify the N functions together in the FuncECs set.
	//
	void EquivClassGraphs::buildIndirectFunctionSets(Module &M) {
	const ActualCalleesTy& AC = CBU->getActualCallees();

	// Loop over all of the indirect calls in the program. If a call site can
	// call multiple different functions, we need to unify all of the callees into
	// the same equivalence class.
	Instruction *LastInst = 0;
	Function *FirstFunc = 0;
	for (ActualCalleesTy::const_iterator I=AC.begin(), E=AC.end(); I != E; ++I) {
	if (I->second->isExternal())
	continue; // Ignore functions we cannot modify

	CallSite CS = CallSite::get(I->first);

	if (CS.getCalledFunction()) { // Direct call:
	FuncECs.insert(I->second); // -- Make sure function has equiv class
	FirstFunc = I->second; // -- First callee at this site
	} else { // Else indirect call
	// DEBUG(std::cerr << "CALLEE: " << I->second->getName()
	// << " from : " << I->first);
	if (I->first != LastInst) {
	// This is the first callee from this call site.
	LastInst = I->first;
	FirstFunc = I->second;
	// Instead of storing the lastInst For Indirection call Sites we store
	// the DSNode for the function ptr arguemnt
	Function *thisFunc = LastInst->getParent()->getParent();
	DSGraph &TFG = CBU->getDSGraph(*thisFunc);
	DSNode *calleeNode = TFG.getNodeForValue(CS.getCalledValue()).getNode();
	OneCalledFunction[calleeNode] = FirstFunc;
	FuncECs.insert(I->second);
	} else {
	// This is not the first possible callee from a particular call site.
	// Union the callee in with the other functions.
	FuncECs.unionSets(FirstFunc, I->second);
	#ifndef NDEBUG
	Function *thisFunc = LastInst->getParent()->getParent();
	DSGraph &TFG = CBU->getDSGraph(*thisFunc);
	DSNode *calleeNode = TFG.getNodeForValue(CS.getCalledValue()).getNode();
	assert(OneCalledFunction.count(calleeNode) > 0 && "Missed a call?");
	#endif
	}
	}

	// Now include all functions that share a graph with any function in the
	// equivalence class. More precisely, if F is in the class, and G(F) is
	// its graph, then we include all other functions that are also in G(F).
	// Currently, that is just the functions in the same call-graph-SCC as F.
	//
	DSGraph& funcDSGraph = CBU->getDSGraph(*I->second);
	for (DSGraph::retnodes_iterator RI = funcDSGraph.retnodes_begin(),
	RE = funcDSGraph.retnodes_end(); RI != RE; ++RI)
	FuncECs.unionSets(FirstFunc, RI->first);
	}

	// Now that all of the equivalences have been built, merge the graphs for
	// each equivalence class.
	//
	DEBUG(std::cerr << "\nIndirect Function Equivalence Sets:\n");
	for (EquivalenceClasses<Function*>::iterator EQSI = FuncECs.begin(), E =
	FuncECs.end(); EQSI != E; ++EQSI) {
	if (!EQSI->isLeader()) continue;

	EquivalenceClasses<Function*>::member_iterator SI =
	FuncECs.member_begin(EQSI);
	assert(SI != FuncECs.member_end() && "Empty equiv set??");
	EquivalenceClasses<Function*>::member_iterator SN = SI;
	++SN;
	if (SN == FuncECs.member_end())
	continue; // Single function equivalence set, no merging to do.

	Function* LF = *SI;

	#ifndef NDEBUG
	DEBUG(std::cerr <<" Equivalence set for leader " << LF->getName() <<" = ");
	for (SN = SI; SN != FuncECs.member_end(); ++SN)
	DEBUG(std::cerr << " " << (*SN)->getName() << "," );
	DEBUG(std::cerr << "\n");
	#endif

	// This equiv class has multiple functions: merge their graphs. First,
	// clone the CBU graph for the leader and make it the common graph for the
	// equivalence graph.
	DSGraph &MergedG = getOrCreateGraph(*LF);

	// Record the argument nodes for use in merging later below.
	std::vector<DSNodeHandle> ArgNodes;

	for (Function::arg_iterator AI = LF->arg_begin(), E = LF->arg_end();
	AI != E; ++AI)
	if (DS::isPointerType(AI->getType()))
	ArgNodes.push_back(MergedG.getNodeForValue(AI));

	// Merge in the graphs of all other functions in this equiv. class. Note
	// that two or more functions may have the same graph, and it only needs
	// to be merged in once.
	std::set<DSGraph*> GraphsMerged;
	GraphsMerged.insert(&CBU->getDSGraph(*LF));

	for (++SI; SI != FuncECs.member_end(); ++SI) {
	Function F = SI;
	DSGraph *&FG = DSInfo[F];

	DSGraph &CBUGraph = CBU->getDSGraph(*F);
	if (GraphsMerged.insert(&CBUGraph).second) {
	// Record the "folded" graph for the function.
	for (DSGraph::retnodes_iterator I = CBUGraph.retnodes_begin(),
	E = CBUGraph.retnodes_end(); I != E; ++I) {
	assert(DSInfo[I->first] == 0 && "Graph already exists for Fn!");
	DSInfo[I->first] = &MergedG;
	}

	// Clone this member of the equivalence class into MergedG.
	MergedG.cloneInto(CBUGraph);
	}

	// Merge the return nodes of all functions together.
	MergedG.getReturnNodes()[LF].mergeWith(MergedG.getReturnNodes()[F]);

	// Merge the function arguments with all argument nodes found so far.
	// If there are extra function args, add them to the vector of argNodes
	Function::arg_iterator AI2 = F->arg_begin(), AI2end = F->arg_end();
	for (unsigned arg = 0, numArgs = ArgNodes.size();
	arg != numArgs && AI2 != AI2end; ++AI2, ++arg)
	if (DS::isPointerType(AI2->getType()))
	ArgNodes[arg].mergeWith(MergedG.getNodeForValue(AI2));

	for ( ; AI2 != AI2end; ++AI2)
	if (DS::isPointerType(AI2->getType()))
	ArgNodes.push_back(MergedG.getNodeForValue(AI2));
	DEBUG(MergedG.AssertGraphOK());
	}
	}
	DEBUG(std::cerr << "\n");
	}


	DSGraph &EquivClassGraphs::getOrCreateGraph(Function &F) {
	// Has the graph already been created?
	DSGraph *&Graph = DSInfo[&F];
	if (Graph) return *Graph;

	DSGraph &CBUGraph = CBU->getDSGraph(F);

	// Copy the CBU graph...
	Graph = new DSGraph(CBUGraph, GlobalECs); // updates the map via reference
	Graph->setGlobalsGraph(&getGlobalsGraph());
	Graph->setPrintAuxCalls();

	// Make sure to update the DSInfo map for all functions in the graph!
	for (DSGraph::retnodes_iterator I = Graph->retnodes_begin();
	I != Graph->retnodes_end(); ++I)
	if (I->first != &F) {
	DSGraph *&FG = DSInfo[I->first];
	assert(FG == 0 && "Merging function in SCC twice?");
	FG = Graph;
	}

	return *Graph;
	}


	unsigned EquivClassGraphs::
	processSCC(DSGraph &FG, std::vector<DSGraph*> &Stack, unsigned &NextID,
	std::map<DSGraph*, unsigned> &ValMap) {
	std::map<DSGraph*, unsigned>::iterator It = ValMap.lower_bound(&FG);
	if (It != ValMap.end() && It->first == &FG)
	return It->second;

	DEBUG(std::cerr << " ProcessSCC for function " << FG.getFunctionNames()
	<< "\n");

	unsigned Min = NextID++, MyID = Min;
	ValMap[&FG] = Min;
	Stack.push_back(&FG);

	// The edges out of the current node are the call site targets...
	for (DSGraph::fc_iterator CI = FG.fc_begin(), CE = FG.fc_end();
	CI != CE; ++CI) {
	Instruction *Call = CI->getCallSite().getInstruction();

	// Loop over all of the actually called functions...
	for (callee_iterator I = callee_begin(Call), E = callee_end(Call);
	I != E; ++I)
	if (!I->second->isExternal()) {
	// Process the callee as necessary.
	unsigned M = processSCC(getOrCreateGraph(*I->second),
	Stack, NextID, ValMap);
	if (M < Min) Min = M;
	}
	}

	assert(ValMap[&FG] == MyID && "SCC construction assumption wrong!");
	if (Min != MyID)
	return Min; // This is part of a larger SCC!

	// If this is a new SCC, process it now.
	bool MergedGraphs = false;
	while (Stack.back() != &FG) {
	DSGraph *NG = Stack.back();
	ValMap[NG] = ~0U;

	// If the SCC found is not the same as those found in CBU, make sure to
	// merge the graphs as appropriate.
	FG.cloneInto(*NG);

	// Update the DSInfo map and delete the old graph...
	for (DSGraph::retnodes_iterator I = NG->retnodes_begin();
	I != NG->retnodes_end(); ++I)
	DSInfo[I->first] = &FG;

	// Remove NG from the ValMap since the pointer may get recycled.
	ValMap.erase(NG);
	delete NG;
	MergedGraphs = true;
	Stack.pop_back();
	}

	// Clean up the graph before we start inlining a bunch again.
	if (MergedGraphs)
	FG.removeTriviallyDeadNodes();

	Stack.pop_back();

	processGraph(FG);
	ValMap[&FG] = ~0U;
	return MyID;
	}


	/// processGraph - Process the CBU graphs for the program in bottom-up order on
	/// the SCC of the __ACTUAL__ call graph. This builds final folded CBU graphs.
	void EquivClassGraphs::processGraph(DSGraph &G) {
	DEBUG(std::cerr << " ProcessGraph for function "
	<< G.getFunctionNames() << "\n");

	hash_set<Instruction*> calls;

	// Else we need to inline some callee graph. Visit all call sites.
	// The edges out of the current node are the call site targets...
	unsigned i = 0;
	for (DSGraph::fc_iterator CI = G.fc_begin(), CE = G.fc_end(); CI != CE;
	++CI, ++i) {
	const DSCallSite &CS = *CI;
	Instruction *TheCall = CS.getCallSite().getInstruction();

	assert(calls.insert(TheCall).second &&
	"Call instruction occurs multiple times in graph??");

	if (CS.getRetVal().isNull() && CS.getNumPtrArgs() == 0)
	continue;

	// Inline the common callee graph into the current graph, if the callee
	// graph has not changed. Note that all callees should have the same
	// graph so we only need to do this once.
	//
	DSGraph* CalleeGraph = NULL;
	callee_iterator I = callee_begin(TheCall), E = callee_end(TheCall);
	unsigned TNum, Num;

	// Loop over all potential callees to find the first non-external callee.
	for (TNum = 0, Num = std::distance(I, E); I != E; ++I, ++TNum)
	if (!I->second->isExternal())
	break;

	// Now check if the graph has changed and if so, clone and inline it.
	if (I != E) {
	Function *CalleeFunc = I->second;

	// Merge the callee's graph into this graph, if not already the same.
	// Callees in the same equivalence class (which subsumes those
	// in the same SCCs) have the same graph. Note that all recursion
	// including self-recursion have been folded in the equiv classes.
	//
	CalleeGraph = &getOrCreateGraph(*CalleeFunc);
	if (CalleeGraph != &G) {
	++NumFoldGraphInlines;
	G.mergeInGraph(CS, CalleeFunc, CalleeGraph,
	DSGraph::StripAllocaBit \|
	DSGraph::DontCloneCallNodes \|
	DSGraph::DontCloneAuxCallNodes);
	DEBUG(std::cerr << " Inlining graph [" << i << "/"
	<< G.getFunctionCalls().size()-1
	<< ":" << TNum << "/" << Num-1 << "] for "
	<< CalleeFunc->getName() << "["
	<< CalleeGraph->getGraphSize() << "+"
	<< CalleeGraph->getAuxFunctionCalls().size()
	<< "] into '" /<< G.getFunctionNames()/ << "' ["
	<< G.getGraphSize() << "+" << G.getAuxFunctionCalls().size()
	<< "]\n");
	}
	}

	#ifndef NDEBUG
	// Now loop over the rest of the callees and make sure they have the
	// same graph as the one inlined above.
	if (CalleeGraph)
	for (++I, ++TNum; I != E; ++I, ++TNum)
	if (!I->second->isExternal())
	assert(CalleeGraph == &getOrCreateGraph(*I->second) &&
	"Callees at a call site have different graphs?");
	#endif
	}

	// Recompute the Incomplete markers.
	G.maskIncompleteMarkers();
	G.markIncompleteNodes(DSGraph::MarkFormalArgs);

	// Delete dead nodes. Treat globals that are unreachable but that can
	// reach live nodes as live.
	G.removeDeadNodes(DSGraph::KeepUnreachableGlobals);

	// When this graph is finalized, clone the globals in the graph into the
	// globals graph to make sure it has everything, from all graphs.
	ReachabilityCloner RC(*G.getGlobalsGraph(), G, DSGraph::StripAllocaBit);

	// Clone everything reachable from globals in the function graph into the
	// globals graph.
	DSScalarMap &MainSM = G.getScalarMap();
	for (DSScalarMap::global_iterator I = MainSM.global_begin(),
	E = MainSM.global_end(); I != E; ++I)
	RC.getClonedNH(MainSM[*I]);

	DEBUG(std::cerr << " -- DONE ProcessGraph for function "
	<< G.getFunctionNames() << "\n");
	}