llvm/lib/Analysis/DataStructure/BottomUpClosure.cpp - toolchain/llvm-project - Gitiles

 //===- BottomUpClosure.cpp - Compute bottom-up interprocedural closure ----===//
 //
 //                     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 BUDataStructures class, which represents the
 // Bottom-Up Interprocedural closure of the data structure graph over the
 // program.  This is useful for applications like pool allocation, but **not**
 // applications like alias analysis.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/Analysis/DataStructure/DataStructure.h"
 #include "llvm/Analysis/DataStructure/DSGraph.h"
 #include "llvm/Module.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Support/Debug.h"
 using namespace llvm;

 namespace {
   Statistic<> MaxSCC("budatastructure", "Maximum SCC Size in Call Graph");
   Statistic<> NumBUInlines("budatastructures", "Number of graphs inlined");
   Statistic<> NumCallEdges("budatastructures", "Number of 'actual' call edges");

   RegisterAnalysis<BUDataStructures>
   X("budatastructure", "Bottom-up Data Structure Analysis");
 }

 // run - Calculate the bottom up data structure graphs for each function in the
 // program.
 //
 bool BUDataStructures::runOnModule(Module &M) {
   LocalDataStructures &LocalDSA = getAnalysis<LocalDataStructures>();
   GlobalECs = LocalDSA.getGlobalECs();

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

   IndCallGraphMap = new std::map<std::vector<Function*>,
                            std::pair<DSGraph*, std::vector<DSNodeHandle> > >();

   std::vector<Function*> Stack;
   hash_map<Function*, unsigned> ValMap;
   unsigned NextID = 1;

   Function *MainFunc = M.getMainFunction();
   if (MainFunc)
     calculateGraphs(MainFunc, Stack, NextID, ValMap);

   // Calculate the graphs for any functions that are unreachable from main...
   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
     if (!I->isExternal() && !DSInfo.count(I)) {
 #ifndef NDEBUG
       if (MainFunc)
         std::cerr << "*** Function unreachable from main: "
                   << I->getName() << "\n";
 #endif
       calculateGraphs(I, Stack, NextID, ValMap);     // Calculate all graphs.
     }

   NumCallEdges += ActualCallees.size();

   // If we computed any temporary indcallgraphs, free them now.
   for (std::map<std::vector<Function*>,
          std::pair<DSGraph*, std::vector<DSNodeHandle> > >::iterator I =
          IndCallGraphMap->begin(), E = IndCallGraphMap->end(); I != E; ++I) {
     I->second.second.clear();  // Drop arg refs into the graph.
     delete I->second.first;
   }
   delete IndCallGraphMap;

   // At the end of the bottom-up pass, the globals graph becomes complete.
   // FIXME: This is not the right way to do this, but it is sorta better than
   // nothing!  In particular, externally visible globals and unresolvable call
   // nodes at the end of the BU phase should make things that they point to
   // incomplete in the globals graph.
   //
   GlobalsGraph->removeTriviallyDeadNodes();
   GlobalsGraph->maskIncompleteMarkers();

   // Mark external globals incomplete.
   GlobalsGraph->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);
   }

   return false;
 }

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

   // Copy the local version into DSInfo...
   Graph = new DSGraph(getAnalysis<LocalDataStructures>().getDSGraph(*F),
                       GlobalECs);

   Graph->setGlobalsGraph(GlobalsGraph);
   Graph->setPrintAuxCalls();

   // Start with a copy of the original call sites...
   Graph->getAuxFunctionCalls() = Graph->getFunctionCalls();
   return *Graph;
 }

 static bool isVAHackFn(const Function *F) {
   return F->getName() == "printf"  || F->getName() == "sscanf" ||
     F->getName() == "fprintf" || F->getName() == "open" ||
     F->getName() == "sprintf" || F->getName() == "fputs" ||
     F->getName() == "fscanf";
 }

 static bool isResolvableFunc(const Function* callee) {
   return !callee->isExternal() || isVAHackFn(callee);
 }

 static void GetAllCallees(const DSCallSite &CS,
                           std::vector<Function*> &Callees) {
   if (CS.isDirectCall()) {
     if (isResolvableFunc(CS.getCalleeFunc()))
       Callees.push_back(CS.getCalleeFunc());
   } else if (!CS.getCalleeNode()->isIncomplete()) {
     // Get all callees.
     unsigned OldSize = Callees.size();
     CS.getCalleeNode()->addFullFunctionList(Callees);

     // If any of the callees are unresolvable, remove the whole batch!
     for (unsigned i = OldSize, e = Callees.size(); i != e; ++i)
       if (!isResolvableFunc(Callees[i])) {
         Callees.erase(Callees.begin()+OldSize, Callees.end());
         return;
       }
   }
 }


 /// GetAllAuxCallees - Return a list containing all of the resolvable callees in
 /// the aux list for the specified graph in the Callees vector.
 static void GetAllAuxCallees(DSGraph &G, std::vector<Function*> &Callees) {
   Callees.clear();
   for (DSGraph::afc_iterator I = G.afc_begin(), E = G.afc_end(); I != E; ++I)
     GetAllCallees(*I, Callees);
 }

 unsigned BUDataStructures::calculateGraphs(Function *F,
                                            std::vector<Function*> &Stack,
                                            unsigned &NextID,
                                      hash_map<Function*, unsigned> &ValMap) {
   assert(!ValMap.count(F) && "Shouldn't revisit functions!");
   unsigned Min = NextID++, MyID = Min;
   ValMap[F] = Min;
   Stack.push_back(F);

   // FIXME!  This test should be generalized to be any function that we have
   // already processed, in the case when there isn't a main or there are
   // unreachable functions!
   if (F->isExternal()) {   // sprintf, fprintf, sscanf, etc...
     // No callees!
     Stack.pop_back();
     ValMap[F] = ~0;
     return Min;
   }

   DSGraph &Graph = getOrCreateGraph(F);

   // Find all callee functions.
   std::vector<Function*> CalleeFunctions;
   GetAllAuxCallees(Graph, CalleeFunctions);

   // The edges out of the current node are the call site targets...
   for (unsigned i = 0, e = CalleeFunctions.size(); i != e; ++i) {
     Function *Callee = CalleeFunctions[i];
     unsigned M;
     // Have we visited the destination function yet?
     hash_map<Function*, unsigned>::iterator It = ValMap.find(Callee);
     if (It == ValMap.end())  // No, visit it now.
       M = calculateGraphs(Callee, Stack, NextID, ValMap);
     else                    // Yes, get it's number.
       M = It->second;
     if (M < Min) Min = M;
   }

   assert(ValMap[F] == 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.
   if (Stack.back() == F) {           // Special case the single "SCC" case here.
     DEBUG(std::cerr << "Visiting single node SCC #: " << MyID << " fn: "
                     << F->getName() << "\n");
     Stack.pop_back();
     DSGraph &G = getDSGraph(*F);
     DEBUG(std::cerr << "  [BU] Calculating graph for: " << F->getName()<< "\n");
     calculateGraph(G);
     DEBUG(std::cerr << "  [BU] Done inlining: " << F->getName() << " ["
                     << G.getGraphSize() << "+" << G.getAuxFunctionCalls().size()
                     << "]\n");

     if (MaxSCC < 1) MaxSCC = 1;

     // Should we revisit the graph?  Only do it if there are now new resolvable
     // callees.
     GetAllAuxCallees(Graph, CalleeFunctions);
     if (!CalleeFunctions.empty()) {
       ValMap.erase(F);
       return calculateGraphs(F, Stack, NextID, ValMap);
     } else {
       ValMap[F] = ~0U;
     }
     return MyID;

   } else {
     // SCCFunctions - Keep track of the functions in the current SCC
     //
     hash_set<DSGraph*> SCCGraphs;

     Function *NF;
     std::vector<Function*>::iterator FirstInSCC = Stack.end();
     DSGraph *SCCGraph = 0;
     do {
       NF = *--FirstInSCC;
       ValMap[NF] = ~0U;

       // Figure out which graph is the largest one, in order to speed things up
       // a bit in situations where functions in the SCC have widely different
       // graph sizes.
       DSGraph &NFGraph = getDSGraph(*NF);
       SCCGraphs.insert(&NFGraph);
       // FIXME: If we used a better way of cloning graphs (ie, just splice all
       // of the nodes into the new graph), this would be completely unneeded!
       if (!SCCGraph || SCCGraph->getGraphSize() < NFGraph.getGraphSize())
         SCCGraph = &NFGraph;
     } while (NF != F);

     std::cerr << "Calculating graph for SCC #: " << MyID << " of size: "
               << SCCGraphs.size() << "\n";

     // Compute the Max SCC Size...
     if (MaxSCC < SCCGraphs.size())
       MaxSCC = SCCGraphs.size();

     // First thing first, collapse all of the DSGraphs into a single graph for
     // the entire SCC.  We computed the largest graph, so clone all of the other
     // (smaller) graphs into it.  Discard all of the old graphs.
     //
     for (hash_set<DSGraph*>::iterator I = SCCGraphs.begin(),
            E = SCCGraphs.end(); I != E; ++I) {
       DSGraph &G = **I;
       if (&G != SCCGraph) {
         SCCGraph->cloneInto(G);

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

     // Clean up the graph before we start inlining a bunch again...
     SCCGraph->removeDeadNodes(DSGraph::KeepUnreachableGlobals);

     // Now that we have one big happy family, resolve all of the call sites in
     // the graph...
     calculateGraph(*SCCGraph);
     DEBUG(std::cerr << "  [BU] Done inlining SCC  [" << SCCGraph->getGraphSize()
                     << "+" << SCCGraph->getAuxFunctionCalls().size() << "]\n");

     std::cerr << "DONE with SCC #: " << MyID << "\n";

     // We never have to revisit "SCC" processed functions...

     // Drop the stuff we don't need from the end of the stack
     Stack.erase(FirstInSCC, Stack.end());
     return MyID;
   }

   return MyID;  // == Min
 }


 // releaseMemory - If the pass pipeline is done with this pass, we can release
 // our memory... here...
 //
 void BUDataStructures::releaseMemory() {
   for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
          E = DSInfo.end(); I != E; ++I) {
     I->second->getReturnNodes().erase(I->first);
     if (I->second->getReturnNodes().empty())
       delete I->second;
   }

   // Empty map so next time memory is released, data structures are not
   // re-deleted.
   DSInfo.clear();
   delete GlobalsGraph;
   GlobalsGraph = 0;
 }

 void BUDataStructures::calculateGraph(DSGraph &Graph) {
   // Move our call site list into TempFCs so that inline call sites go into the
   // new call site list and doesn't invalidate our iterators!
   std::list<DSCallSite> TempFCs;
   std::list<DSCallSite> &AuxCallsList = Graph.getAuxFunctionCalls();
   TempFCs.swap(AuxCallsList);

   DSGraph::ReturnNodesTy &ReturnNodes = Graph.getReturnNodes();

   bool Printed = false;
   std::vector<Function*> CalledFuncs;
   while (!TempFCs.empty()) {
     DSCallSite &CS = *TempFCs.begin();

     CalledFuncs.clear();

     // Fast path for noop calls.  Note that we don't care about merging globals
     // in the callee with nodes in the caller here.
     if (CS.getRetVal().isNull() && CS.getNumPtrArgs() == 0) {
       TempFCs.erase(TempFCs.begin());
       continue;
     } else if (CS.isDirectCall() && isVAHackFn(CS.getCalleeFunc())) {
       TempFCs.erase(TempFCs.begin());
       continue;
     }

     GetAllCallees(CS, CalledFuncs);

     if (CalledFuncs.empty()) {
       // Remember that we could not resolve this yet!
       AuxCallsList.splice(AuxCallsList.end(), TempFCs, TempFCs.begin());
       continue;
     } else {
       DSGraph *GI;
       Instruction *TheCall = CS.getCallSite().getInstruction();

       if (CalledFuncs.size() == 1) {
         Function *Callee = CalledFuncs[0];
         ActualCallees.insert(std::make_pair(TheCall, Callee));

         // Get the data structure graph for the called function.
         GI = &getDSGraph(*Callee);  // Graph to inline
         DEBUG(std::cerr << "    Inlining graph for " << Callee->getName());

         DEBUG(std::cerr << "[" << GI->getGraphSize() << "+"
               << GI->getAuxFunctionCalls().size() << "] into '"
               << Graph.getFunctionNames() << "' [" << Graph.getGraphSize() <<"+"
               << Graph.getAuxFunctionCalls().size() << "]\n");
         Graph.mergeInGraph(CS, *Callee, *GI,
                            DSGraph::KeepModRefBits |
                            DSGraph::StripAllocaBit|DSGraph::DontCloneCallNodes);
         ++NumBUInlines;
       } else {
         if (!Printed)
           std::cerr << "In Fns: " << Graph.getFunctionNames() << "\n";
         std::cerr << "  calls " << CalledFuncs.size()
                   << " fns from site: " << CS.getCallSite().getInstruction()
                   << "  " << *CS.getCallSite().getInstruction();
         std::cerr << "   Fns =";
         unsigned NumPrinted = 0;

         for (std::vector<Function*>::iterator I = CalledFuncs.begin(),
                E = CalledFuncs.end(); I != E; ++I) {
           if (NumPrinted++ < 8) std::cerr << " " << (*I)->getName();

           // Add the call edges to the call graph.
           ActualCallees.insert(std::make_pair(TheCall, *I));
         }
         std::cerr << "\n";

         // See if we already computed a graph for this set of callees.
         std::sort(CalledFuncs.begin(), CalledFuncs.end());
         std::pair<DSGraph*, std::vector<DSNodeHandle> > &IndCallGraph =
           (*IndCallGraphMap)[CalledFuncs];

         if (IndCallGraph.first == 0) {
           std::vector<Function*>::iterator I = CalledFuncs.begin(),
             E = CalledFuncs.end();

           // Start with a copy of the first graph.
           GI = IndCallGraph.first = new DSGraph(getDSGraph(**I), GlobalECs);
           GI->setGlobalsGraph(Graph.getGlobalsGraph());
           std::vector<DSNodeHandle> &Args = IndCallGraph.second;

           // Get the argument nodes for the first callee.  The return value is
           // the 0th index in the vector.
           GI->getFunctionArgumentsForCall(*I, Args);

           // Merge all of the other callees into this graph.
           for (++I; I != E; ++I) {
             // If the graph already contains the nodes for the function, don't
             // bother merging it in again.
             if (!GI->containsFunction(*I)) {
               GI->cloneInto(getDSGraph(**I));
               ++NumBUInlines;
             }

             std::vector<DSNodeHandle> NextArgs;
             GI->getFunctionArgumentsForCall(*I, NextArgs);
             unsigned i = 0, e = Args.size();
             for (; i != e; ++i) {
               if (i == NextArgs.size()) break;
               Args[i].mergeWith(NextArgs[i]);
             }
             for (e = NextArgs.size(); i != e; ++i)
               Args.push_back(NextArgs[i]);
           }

           // Clean up the final graph!
           GI->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
         } else {
           std::cerr << "***\n*** RECYCLED GRAPH ***\n***\n";
         }

         GI = IndCallGraph.first;

         // Merge the unified graph into this graph now.
         DEBUG(std::cerr << "    Inlining multi callee graph "
               << "[" << GI->getGraphSize() << "+"
               << GI->getAuxFunctionCalls().size() << "] into '"
               << Graph.getFunctionNames() << "' [" << Graph.getGraphSize() <<"+"
               << Graph.getAuxFunctionCalls().size() << "]\n");

         Graph.mergeInGraph(CS, IndCallGraph.second, *GI,
                            DSGraph::KeepModRefBits |
                            DSGraph::StripAllocaBit |
                            DSGraph::DontCloneCallNodes);
         ++NumBUInlines;
       }
     }
     TempFCs.erase(TempFCs.begin());
   }

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

   // Delete dead nodes.  Treat globals that are unreachable but that can
   // reach live nodes as live.
   Graph.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.
   DSScalarMap &MainSM = Graph.getScalarMap();
   ReachabilityCloner RC(*GlobalsGraph, Graph, DSGraph::StripAllocaBit);

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

   //Graph.writeGraphToFile(std::cerr, "bu_" + F.getName());
 }

 static const Function *getFnForValue(const Value *V) {
   if (const Instruction *I = dyn_cast<Instruction>(V))
     return I->getParent()->getParent();
   else if (const Argument *A = dyn_cast<Argument>(V))
     return A->getParent();
   else if (const BasicBlock *BB = dyn_cast<BasicBlock>(V))
     return BB->getParent();
   return 0;
 }

 /// deleteValue/copyValue - Interfaces to update the DSGraphs in the program.
 /// These correspond to the interfaces defined in the AliasAnalysis class.
 void BUDataStructures::deleteValue(Value *V) {
   if (const Function *F = getFnForValue(V)) {  // Function local value?
     // If this is a function local value, just delete it from the scalar map!
     getDSGraph(*F).getScalarMap().eraseIfExists(V);
     return;
   }

   if (Function *F = dyn_cast<Function>(V)) {
     assert(getDSGraph(*F).getReturnNodes().size() == 1 &&
            "cannot handle scc's");
     delete DSInfo[F];
     DSInfo.erase(F);
     return;
   }

   assert(!isa<GlobalVariable>(V) && "Do not know how to delete GV's yet!");
 }

 void BUDataStructures::copyValue(Value *From, Value *To) {
   if (From == To) return;
   if (const Function *F = getFnForValue(From)) {  // Function local value?
     // If this is a function local value, just delete it from the scalar map!
     getDSGraph(*F).getScalarMap().copyScalarIfExists(From, To);
     return;
   }

   if (Function *FromF = dyn_cast<Function>(From)) {
     Function *ToF = cast<Function>(To);
     assert(!DSInfo.count(ToF) && "New Function already exists!");
     DSGraph *NG = new DSGraph(getDSGraph(*FromF), GlobalECs);
     DSInfo[ToF] = NG;
     assert(NG->getReturnNodes().size() == 1 && "Cannot copy SCC's yet!");

     // Change the Function* is the returnnodes map to the ToF.
     DSNodeHandle Ret = NG->retnodes_begin()->second;
     NG->getReturnNodes().clear();
     NG->getReturnNodes()[ToF] = Ret;
     return;
   }

   assert(!isa<GlobalVariable>(From) && "Do not know how to copy GV's yet!");
 }
	//===- BottomUpClosure.cpp - Compute bottom-up interprocedural closure ----===//
	//
	// 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 BUDataStructures class, which represents the
	// Bottom-Up Interprocedural closure of the data structure graph over the
	// program. This is useful for applications like pool allocation, but not
	// applications like alias analysis.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/Analysis/DataStructure/DataStructure.h"
	#include "llvm/Analysis/DataStructure/DSGraph.h"
	#include "llvm/Module.h"
	#include "llvm/ADT/Statistic.h"
	#include "llvm/Support/Debug.h"
	using namespace llvm;

	namespace {
	Statistic<> MaxSCC("budatastructure", "Maximum SCC Size in Call Graph");
	Statistic<> NumBUInlines("budatastructures", "Number of graphs inlined");
	Statistic<> NumCallEdges("budatastructures", "Number of 'actual' call edges");

	RegisterAnalysis<BUDataStructures>
	X("budatastructure", "Bottom-up Data Structure Analysis");
	}

	// run - Calculate the bottom up data structure graphs for each function in the
	// program.
	//
	bool BUDataStructures::runOnModule(Module &M) {
	LocalDataStructures &LocalDSA = getAnalysis<LocalDataStructures>();
	GlobalECs = LocalDSA.getGlobalECs();

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

	IndCallGraphMap = new std::map<std::vector<Function*>,
	std::pair<DSGraph*, std::vector<DSNodeHandle> > >();

	std::vector<Function*> Stack;
	hash_map<Function*, unsigned> ValMap;
	unsigned NextID = 1;

	Function *MainFunc = M.getMainFunction();
	if (MainFunc)
	calculateGraphs(MainFunc, Stack, NextID, ValMap);

	// Calculate the graphs for any functions that are unreachable from main...
	for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
	if (!I->isExternal() && !DSInfo.count(I)) {
	#ifndef NDEBUG
	if (MainFunc)
	std::cerr << "*** Function unreachable from main: "
	<< I->getName() << "\n";
	#endif
	calculateGraphs(I, Stack, NextID, ValMap); // Calculate all graphs.
	}

	NumCallEdges += ActualCallees.size();

	// If we computed any temporary indcallgraphs, free them now.
	for (std::map<std::vector<Function*>,
	std::pair<DSGraph*, std::vector<DSNodeHandle> > >::iterator I =
	IndCallGraphMap->begin(), E = IndCallGraphMap->end(); I != E; ++I) {
	I->second.second.clear(); // Drop arg refs into the graph.
	delete I->second.first;
	}
	delete IndCallGraphMap;

	// At the end of the bottom-up pass, the globals graph becomes complete.
	// FIXME: This is not the right way to do this, but it is sorta better than
	// nothing! In particular, externally visible globals and unresolvable call
	// nodes at the end of the BU phase should make things that they point to
	// incomplete in the globals graph.
	//
	GlobalsGraph->removeTriviallyDeadNodes();
	GlobalsGraph->maskIncompleteMarkers();

	// Mark external globals incomplete.
	GlobalsGraph->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);
	}

	return false;
	}

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

	// Copy the local version into DSInfo...
	Graph = new DSGraph(getAnalysis<LocalDataStructures>().getDSGraph(*F),
	GlobalECs);

	Graph->setGlobalsGraph(GlobalsGraph);
	Graph->setPrintAuxCalls();

	// Start with a copy of the original call sites...
	Graph->getAuxFunctionCalls() = Graph->getFunctionCalls();
	return *Graph;
	}

	static bool isVAHackFn(const Function *F) {
	return F->getName() == "printf" \|\| F->getName() == "sscanf" \|\|
	F->getName() == "fprintf" \|\| F->getName() == "open" \|\|
	F->getName() == "sprintf" \|\| F->getName() == "fputs" \|\|
	F->getName() == "fscanf";
	}

	static bool isResolvableFunc(const Function* callee) {
	return !callee->isExternal() \|\| isVAHackFn(callee);
	}

	static void GetAllCallees(const DSCallSite &CS,
	std::vector<Function*> &Callees) {
	if (CS.isDirectCall()) {
	if (isResolvableFunc(CS.getCalleeFunc()))
	Callees.push_back(CS.getCalleeFunc());
	} else if (!CS.getCalleeNode()->isIncomplete()) {
	// Get all callees.
	unsigned OldSize = Callees.size();
	CS.getCalleeNode()->addFullFunctionList(Callees);

	// If any of the callees are unresolvable, remove the whole batch!
	for (unsigned i = OldSize, e = Callees.size(); i != e; ++i)
	if (!isResolvableFunc(Callees[i])) {
	Callees.erase(Callees.begin()+OldSize, Callees.end());
	return;
	}
	}
	}


	/// GetAllAuxCallees - Return a list containing all of the resolvable callees in
	/// the aux list for the specified graph in the Callees vector.
	static void GetAllAuxCallees(DSGraph &G, std::vector<Function*> &Callees) {
	Callees.clear();
	for (DSGraph::afc_iterator I = G.afc_begin(), E = G.afc_end(); I != E; ++I)
	GetAllCallees(*I, Callees);
	}

	unsigned BUDataStructures::calculateGraphs(Function *F,
	std::vector<Function*> &Stack,
	unsigned &NextID,
	hash_map<Function*, unsigned> &ValMap) {
	assert(!ValMap.count(F) && "Shouldn't revisit functions!");
	unsigned Min = NextID++, MyID = Min;
	ValMap[F] = Min;
	Stack.push_back(F);

	// FIXME! This test should be generalized to be any function that we have
	// already processed, in the case when there isn't a main or there are
	// unreachable functions!
	if (F->isExternal()) { // sprintf, fprintf, sscanf, etc...
	// No callees!
	Stack.pop_back();
	ValMap[F] = ~0;
	return Min;
	}

	DSGraph &Graph = getOrCreateGraph(F);

	// Find all callee functions.
	std::vector<Function*> CalleeFunctions;
	GetAllAuxCallees(Graph, CalleeFunctions);

	// The edges out of the current node are the call site targets...
	for (unsigned i = 0, e = CalleeFunctions.size(); i != e; ++i) {
	Function *Callee = CalleeFunctions[i];
	unsigned M;
	// Have we visited the destination function yet?
	hash_map<Function*, unsigned>::iterator It = ValMap.find(Callee);
	if (It == ValMap.end()) // No, visit it now.
	M = calculateGraphs(Callee, Stack, NextID, ValMap);
	else // Yes, get it's number.
	M = It->second;
	if (M < Min) Min = M;
	}

	assert(ValMap[F] == 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.
	if (Stack.back() == F) { // Special case the single "SCC" case here.
	DEBUG(std::cerr << "Visiting single node SCC #: " << MyID << " fn: "
	<< F->getName() << "\n");
	Stack.pop_back();
	DSGraph &G = getDSGraph(*F);
	DEBUG(std::cerr << " [BU] Calculating graph for: " << F->getName()<< "\n");
	calculateGraph(G);
	DEBUG(std::cerr << " [BU] Done inlining: " << F->getName() << " ["
	<< G.getGraphSize() << "+" << G.getAuxFunctionCalls().size()
	<< "]\n");

	if (MaxSCC < 1) MaxSCC = 1;

	// Should we revisit the graph? Only do it if there are now new resolvable
	// callees.
	GetAllAuxCallees(Graph, CalleeFunctions);
	if (!CalleeFunctions.empty()) {
	ValMap.erase(F);
	return calculateGraphs(F, Stack, NextID, ValMap);
	} else {
	ValMap[F] = ~0U;
	}
	return MyID;

	} else {
	// SCCFunctions - Keep track of the functions in the current SCC
	//
	hash_set<DSGraph*> SCCGraphs;

	Function *NF;
	std::vector<Function*>::iterator FirstInSCC = Stack.end();
	DSGraph *SCCGraph = 0;
	do {
	NF = *--FirstInSCC;
	ValMap[NF] = ~0U;

	// Figure out which graph is the largest one, in order to speed things up
	// a bit in situations where functions in the SCC have widely different
	// graph sizes.
	DSGraph &NFGraph = getDSGraph(*NF);
	SCCGraphs.insert(&NFGraph);
	// FIXME: If we used a better way of cloning graphs (ie, just splice all
	// of the nodes into the new graph), this would be completely unneeded!
	if (!SCCGraph \|\| SCCGraph->getGraphSize() < NFGraph.getGraphSize())
	SCCGraph = &NFGraph;
	} while (NF != F);

	std::cerr << "Calculating graph for SCC #: " << MyID << " of size: "
	<< SCCGraphs.size() << "\n";

	// Compute the Max SCC Size...
	if (MaxSCC < SCCGraphs.size())
	MaxSCC = SCCGraphs.size();

	// First thing first, collapse all of the DSGraphs into a single graph for
	// the entire SCC. We computed the largest graph, so clone all of the other
	// (smaller) graphs into it. Discard all of the old graphs.
	//
	for (hash_set<DSGraph*>::iterator I = SCCGraphs.begin(),
	E = SCCGraphs.end(); I != E; ++I) {
	DSGraph &G = **I;
	if (&G != SCCGraph) {
	SCCGraph->cloneInto(G);

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

	// Clean up the graph before we start inlining a bunch again...
	SCCGraph->removeDeadNodes(DSGraph::KeepUnreachableGlobals);

	// Now that we have one big happy family, resolve all of the call sites in
	// the graph...
	calculateGraph(*SCCGraph);
	DEBUG(std::cerr << " [BU] Done inlining SCC [" << SCCGraph->getGraphSize()
	<< "+" << SCCGraph->getAuxFunctionCalls().size() << "]\n");

	std::cerr << "DONE with SCC #: " << MyID << "\n";

	// We never have to revisit "SCC" processed functions...

	// Drop the stuff we don't need from the end of the stack
	Stack.erase(FirstInSCC, Stack.end());
	return MyID;
	}

	return MyID; // == Min
	}


	// releaseMemory - If the pass pipeline is done with this pass, we can release
	// our memory... here...
	//
	void BUDataStructures::releaseMemory() {
	for (hash_map<Function, DSGraph>::iterator I = DSInfo.begin(),
	E = DSInfo.end(); I != E; ++I) {
	I->second->getReturnNodes().erase(I->first);
	if (I->second->getReturnNodes().empty())
	delete I->second;
	}

	// Empty map so next time memory is released, data structures are not
	// re-deleted.
	DSInfo.clear();
	delete GlobalsGraph;
	GlobalsGraph = 0;
	}

	void BUDataStructures::calculateGraph(DSGraph &Graph) {
	// Move our call site list into TempFCs so that inline call sites go into the
	// new call site list and doesn't invalidate our iterators!
	std::list<DSCallSite> TempFCs;
	std::list<DSCallSite> &AuxCallsList = Graph.getAuxFunctionCalls();
	TempFCs.swap(AuxCallsList);

	DSGraph::ReturnNodesTy &ReturnNodes = Graph.getReturnNodes();

	bool Printed = false;
	std::vector<Function*> CalledFuncs;
	while (!TempFCs.empty()) {
	DSCallSite &CS = *TempFCs.begin();

	CalledFuncs.clear();

	// Fast path for noop calls. Note that we don't care about merging globals
	// in the callee with nodes in the caller here.
	if (CS.getRetVal().isNull() && CS.getNumPtrArgs() == 0) {
	TempFCs.erase(TempFCs.begin());
	continue;
	} else if (CS.isDirectCall() && isVAHackFn(CS.getCalleeFunc())) {
	TempFCs.erase(TempFCs.begin());
	continue;
	}

	GetAllCallees(CS, CalledFuncs);

	if (CalledFuncs.empty()) {
	// Remember that we could not resolve this yet!
	AuxCallsList.splice(AuxCallsList.end(), TempFCs, TempFCs.begin());
	continue;
	} else {
	DSGraph *GI;
	Instruction *TheCall = CS.getCallSite().getInstruction();

	if (CalledFuncs.size() == 1) {
	Function *Callee = CalledFuncs[0];
	ActualCallees.insert(std::make_pair(TheCall, Callee));

	// Get the data structure graph for the called function.
	GI = &getDSGraph(*Callee); // Graph to inline
	DEBUG(std::cerr << " Inlining graph for " << Callee->getName());

	DEBUG(std::cerr << "[" << GI->getGraphSize() << "+"
	<< GI->getAuxFunctionCalls().size() << "] into '"
	<< Graph.getFunctionNames() << "' [" << Graph.getGraphSize() <<"+"
	<< Graph.getAuxFunctionCalls().size() << "]\n");
	Graph.mergeInGraph(CS, Callee, GI,
	DSGraph::KeepModRefBits \|
	DSGraph::StripAllocaBit\|DSGraph::DontCloneCallNodes);
	++NumBUInlines;
	} else {
	if (!Printed)
	std::cerr << "In Fns: " << Graph.getFunctionNames() << "\n";
	std::cerr << " calls " << CalledFuncs.size()
	<< " fns from site: " << CS.getCallSite().getInstruction()
	<< " " << *CS.getCallSite().getInstruction();
	std::cerr << " Fns =";
	unsigned NumPrinted = 0;

	for (std::vector<Function*>::iterator I = CalledFuncs.begin(),
	E = CalledFuncs.end(); I != E; ++I) {
	if (NumPrinted++ < 8) std::cerr << " " << (*I)->getName();

	// Add the call edges to the call graph.
	ActualCallees.insert(std::make_pair(TheCall, *I));
	}
	std::cerr << "\n";

	// See if we already computed a graph for this set of callees.
	std::sort(CalledFuncs.begin(), CalledFuncs.end());
	std::pair<DSGraph*, std::vector<DSNodeHandle> > &IndCallGraph =
	(*IndCallGraphMap)[CalledFuncs];

	if (IndCallGraph.first == 0) {
	std::vector<Function*>::iterator I = CalledFuncs.begin(),
	E = CalledFuncs.end();

	// Start with a copy of the first graph.
	GI = IndCallGraph.first = new DSGraph(getDSGraph(**I), GlobalECs);
	GI->setGlobalsGraph(Graph.getGlobalsGraph());
	std::vector<DSNodeHandle> &Args = IndCallGraph.second;

	// Get the argument nodes for the first callee. The return value is
	// the 0th index in the vector.
	GI->getFunctionArgumentsForCall(*I, Args);

	// Merge all of the other callees into this graph.
	for (++I; I != E; ++I) {
	// If the graph already contains the nodes for the function, don't
	// bother merging it in again.
	if (!GI->containsFunction(*I)) {
	GI->cloneInto(getDSGraph(**I));
	++NumBUInlines;
	}

	std::vector<DSNodeHandle> NextArgs;
	GI->getFunctionArgumentsForCall(*I, NextArgs);
	unsigned i = 0, e = Args.size();
	for (; i != e; ++i) {
	if (i == NextArgs.size()) break;
	Args[i].mergeWith(NextArgs[i]);
	}
	for (e = NextArgs.size(); i != e; ++i)
	Args.push_back(NextArgs[i]);
	}

	// Clean up the final graph!
	GI->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
	} else {
	std::cerr << "*\n* RECYCLED GRAPH *\n*\n";
	}

	GI = IndCallGraph.first;

	// Merge the unified graph into this graph now.
	DEBUG(std::cerr << " Inlining multi callee graph "
	<< "[" << GI->getGraphSize() << "+"
	<< GI->getAuxFunctionCalls().size() << "] into '"
	<< Graph.getFunctionNames() << "' [" << Graph.getGraphSize() <<"+"
	<< Graph.getAuxFunctionCalls().size() << "]\n");

	Graph.mergeInGraph(CS, IndCallGraph.second, *GI,
	DSGraph::KeepModRefBits \|
	DSGraph::StripAllocaBit \|
	DSGraph::DontCloneCallNodes);
	++NumBUInlines;
	}
	}
	TempFCs.erase(TempFCs.begin());
	}

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

	// Delete dead nodes. Treat globals that are unreachable but that can
	// reach live nodes as live.
	Graph.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.
	DSScalarMap &MainSM = Graph.getScalarMap();
	ReachabilityCloner RC(*GlobalsGraph, Graph, DSGraph::StripAllocaBit);

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

	//Graph.writeGraphToFile(std::cerr, "bu_" + F.getName());
	}

	static const Function getFnForValue(const Value V) {
	if (const Instruction *I = dyn_cast<Instruction>(V))
	return I->getParent()->getParent();
	else if (const Argument *A = dyn_cast<Argument>(V))
	return A->getParent();
	else if (const BasicBlock *BB = dyn_cast<BasicBlock>(V))
	return BB->getParent();
	return 0;
	}

	/// deleteValue/copyValue - Interfaces to update the DSGraphs in the program.
	/// These correspond to the interfaces defined in the AliasAnalysis class.
	void BUDataStructures::deleteValue(Value *V) {
	if (const Function *F = getFnForValue(V)) { // Function local value?
	// If this is a function local value, just delete it from the scalar map!
	getDSGraph(*F).getScalarMap().eraseIfExists(V);
	return;
	}

	if (Function *F = dyn_cast<Function>(V)) {
	assert(getDSGraph(*F).getReturnNodes().size() == 1 &&
	"cannot handle scc's");
	delete DSInfo[F];
	DSInfo.erase(F);
	return;
	}

	assert(!isa<GlobalVariable>(V) && "Do not know how to delete GV's yet!");
	}

	void BUDataStructures::copyValue(Value From, Value To) {
	if (From == To) return;
	if (const Function *F = getFnForValue(From)) { // Function local value?
	// If this is a function local value, just delete it from the scalar map!
	getDSGraph(*F).getScalarMap().copyScalarIfExists(From, To);
	return;
	}

	if (Function *FromF = dyn_cast<Function>(From)) {
	Function *ToF = cast<Function>(To);
	assert(!DSInfo.count(ToF) && "New Function already exists!");
	DSGraph NG = new DSGraph(getDSGraph(FromF), GlobalECs);
	DSInfo[ToF] = NG;
	assert(NG->getReturnNodes().size() == 1 && "Cannot copy SCC's yet!");

	// Change the Function* is the returnnodes map to the ToF.
	DSNodeHandle Ret = NG->retnodes_begin()->second;
	NG->getReturnNodes().clear();
	NG->getReturnNodes()[ToF] = Ret;
	return;
	}

	assert(!isa<GlobalVariable>(From) && "Do not know how to copy GV's yet!");
	}