LLVM API Documentation

BottomUpClosure.cpp

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00001 //===- BottomUpClosure.cpp - Compute bottom-up interprocedural closure ----===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file implements the BUDataStructures class, which represents the
00011 // Bottom-Up Interprocedural closure of the data structure graph over the
00012 // program.  This is useful for applications like pool allocation, but **not**
00013 // applications like alias analysis.
00014 //
00015 //===----------------------------------------------------------------------===//
00016 
00017 #include "llvm/Analysis/DataStructure/DataStructure.h"
00018 #include "llvm/Analysis/DataStructure/DSGraph.h"
00019 #include "llvm/Module.h"
00020 #include "llvm/ADT/Statistic.h"
00021 #include "llvm/Support/Debug.h"
00022 #include "llvm/Support/Timer.h"
00023 #include <iostream>
00024 using namespace llvm;
00025 
00026 namespace {
00027   Statistic<> MaxSCC("budatastructure", "Maximum SCC Size in Call Graph");
00028   Statistic<> NumBUInlines("budatastructures", "Number of graphs inlined");
00029   Statistic<> NumCallEdges("budatastructures", "Number of 'actual' call edges");
00030 
00031   RegisterAnalysis<BUDataStructures>
00032   X("budatastructure", "Bottom-up Data Structure Analysis");
00033 }
00034 
00035 /// BuildGlobalECs - Look at all of the nodes in the globals graph.  If any node
00036 /// contains multiple globals, DSA will never, ever, be able to tell the globals
00037 /// apart.  Instead of maintaining this information in all of the graphs
00038 /// throughout the entire program, store only a single global (the "leader") in
00039 /// the graphs, and build equivalence classes for the rest of the globals.
00040 static void BuildGlobalECs(DSGraph &GG, std::set<GlobalValue*> &ECGlobals) {
00041   DSScalarMap &SM = GG.getScalarMap();
00042   EquivalenceClasses<GlobalValue*> &GlobalECs = SM.getGlobalECs();
00043   for (DSGraph::node_iterator I = GG.node_begin(), E = GG.node_end();
00044        I != E; ++I) {
00045     if (I->getGlobalsList().size() <= 1) continue;
00046 
00047     // First, build up the equivalence set for this block of globals.
00048     const std::vector<GlobalValue*> &GVs = I->getGlobalsList();
00049     GlobalValue *First = GVs[0];
00050     for (unsigned i = 1, e = GVs.size(); i != e; ++i)
00051       GlobalECs.unionSets(First, GVs[i]);
00052 
00053     // Next, get the leader element.
00054     assert(First == GlobalECs.getLeaderValue(First) &&
00055            "First did not end up being the leader?");
00056 
00057     // Next, remove all globals from the scalar map that are not the leader.
00058     assert(GVs[0] == First && "First had to be at the front!");
00059     for (unsigned i = 1, e = GVs.size(); i != e; ++i) {
00060       ECGlobals.insert(GVs[i]);
00061       SM.erase(SM.find(GVs[i]));
00062     }
00063 
00064     // Finally, change the global node to only contain the leader.
00065     I->clearGlobals();
00066     I->addGlobal(First);
00067   }
00068 
00069   DEBUG(GG.AssertGraphOK());
00070 }
00071 
00072 /// EliminateUsesOfECGlobals - Once we have determined that some globals are in
00073 /// really just equivalent to some other globals, remove the globals from the
00074 /// specified DSGraph (if present), and merge any nodes with their leader nodes.
00075 static void EliminateUsesOfECGlobals(DSGraph &G,
00076                                      const std::set<GlobalValue*> &ECGlobals) {
00077   DSScalarMap &SM = G.getScalarMap();
00078   EquivalenceClasses<GlobalValue*> &GlobalECs = SM.getGlobalECs();
00079 
00080   bool MadeChange = false;
00081   for (DSScalarMap::global_iterator GI = SM.global_begin(), E = SM.global_end();
00082        GI != E; ) {
00083     GlobalValue *GV = *GI++;
00084     if (!ECGlobals.count(GV)) continue;
00085 
00086     const DSNodeHandle &GVNH = SM[GV];
00087     assert(!GVNH.isNull() && "Global has null NH!?");
00088 
00089     // Okay, this global is in some equivalence class.  Start by finding the
00090     // leader of the class.
00091     GlobalValue *Leader = GlobalECs.getLeaderValue(GV);
00092 
00093     // If the leader isn't already in the graph, insert it into the node
00094     // corresponding to GV.
00095     if (!SM.global_count(Leader)) {
00096       GVNH.getNode()->addGlobal(Leader);
00097       SM[Leader] = GVNH;
00098     } else {
00099       // Otherwise, the leader is in the graph, make sure the nodes are the
00100       // merged in the specified graph.
00101       const DSNodeHandle &LNH = SM[Leader];
00102       if (LNH.getNode() != GVNH.getNode())
00103         LNH.mergeWith(GVNH);
00104     }
00105 
00106     // Next step, remove the global from the DSNode.
00107     GVNH.getNode()->removeGlobal(GV);
00108 
00109     // Finally, remove the global from the ScalarMap.
00110     SM.erase(GV);
00111     MadeChange = true;
00112   }
00113 
00114   DEBUG(if(MadeChange) G.AssertGraphOK());
00115 }
00116 
00117 // run - Calculate the bottom up data structure graphs for each function in the
00118 // program.
00119 //
00120 bool BUDataStructures::runOnModule(Module &M) {
00121   LocalDataStructures &LocalDSA = getAnalysis<LocalDataStructures>();
00122   GlobalECs = LocalDSA.getGlobalECs();
00123 
00124   GlobalsGraph = new DSGraph(LocalDSA.getGlobalsGraph(), GlobalECs);
00125   GlobalsGraph->setPrintAuxCalls();
00126 
00127   IndCallGraphMap = new std::map<std::vector<Function*>,
00128                            std::pair<DSGraph*, std::vector<DSNodeHandle> > >();
00129 
00130   std::vector<Function*> Stack;
00131   hash_map<Function*, unsigned> ValMap;
00132   unsigned NextID = 1;
00133 
00134   Function *MainFunc = M.getMainFunction();
00135   if (MainFunc)
00136     calculateGraphs(MainFunc, Stack, NextID, ValMap);
00137 
00138   // Calculate the graphs for any functions that are unreachable from main...
00139   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
00140     if (!I->isExternal() && !DSInfo.count(I)) {
00141 #ifndef NDEBUG
00142       if (MainFunc)
00143         std::cerr << "*** Function unreachable from main: "
00144                   << I->getName() << "\n";
00145 #endif
00146       calculateGraphs(I, Stack, NextID, ValMap);     // Calculate all graphs.
00147     }
00148 
00149   NumCallEdges += ActualCallees.size();
00150 
00151   // If we computed any temporary indcallgraphs, free them now.
00152   for (std::map<std::vector<Function*>,
00153          std::pair<DSGraph*, std::vector<DSNodeHandle> > >::iterator I =
00154          IndCallGraphMap->begin(), E = IndCallGraphMap->end(); I != E; ++I) {
00155     I->second.second.clear();  // Drop arg refs into the graph.
00156     delete I->second.first;
00157   }
00158   delete IndCallGraphMap;
00159 
00160   // At the end of the bottom-up pass, the globals graph becomes complete.
00161   // FIXME: This is not the right way to do this, but it is sorta better than
00162   // nothing!  In particular, externally visible globals and unresolvable call
00163   // nodes at the end of the BU phase should make things that they point to
00164   // incomplete in the globals graph.
00165   //
00166   GlobalsGraph->removeTriviallyDeadNodes();
00167   GlobalsGraph->maskIncompleteMarkers();
00168 
00169   // Mark external globals incomplete.
00170   GlobalsGraph->markIncompleteNodes(DSGraph::IgnoreGlobals);
00171 
00172   // Grow the equivalence classes for the globals to include anything that we
00173   // now know to be aliased.
00174   std::set<GlobalValue*> ECGlobals;
00175   BuildGlobalECs(*GlobalsGraph, ECGlobals);
00176   if (!ECGlobals.empty()) {
00177     NamedRegionTimer X("Bottom-UP EC Cleanup");
00178     std::cerr << "Eliminating " << ECGlobals.size() << " EC Globals!\n";
00179     for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
00180            E = DSInfo.end(); I != E; ++I)
00181       EliminateUsesOfECGlobals(*I->second, ECGlobals);
00182   }
00183 
00184   // Merge the globals variables (not the calls) from the globals graph back
00185   // into the main function's graph so that the main function contains all of
00186   // the information about global pools and GV usage in the program.
00187   if (MainFunc && !MainFunc->isExternal()) {
00188     DSGraph &MainGraph = getOrCreateGraph(MainFunc);
00189     const DSGraph &GG = *MainGraph.getGlobalsGraph();
00190     ReachabilityCloner RC(MainGraph, GG,
00191                           DSGraph::DontCloneCallNodes |
00192                           DSGraph::DontCloneAuxCallNodes);
00193 
00194     // Clone the global nodes into this graph.
00195     for (DSScalarMap::global_iterator I = GG.getScalarMap().global_begin(),
00196            E = GG.getScalarMap().global_end(); I != E; ++I)
00197       if (isa<GlobalVariable>(*I))
00198         RC.getClonedNH(GG.getNodeForValue(*I));
00199 
00200     MainGraph.maskIncompleteMarkers();
00201     MainGraph.markIncompleteNodes(DSGraph::MarkFormalArgs |
00202                                   DSGraph::IgnoreGlobals);
00203   }
00204 
00205   return false;
00206 }
00207 
00208 DSGraph &BUDataStructures::getOrCreateGraph(Function *F) {
00209   // Has the graph already been created?
00210   DSGraph *&Graph = DSInfo[F];
00211   if (Graph) return *Graph;
00212 
00213   DSGraph &LocGraph = getAnalysis<LocalDataStructures>().getDSGraph(*F);
00214 
00215   // Steal the local graph.
00216   Graph = new DSGraph(GlobalECs, LocGraph.getTargetData());
00217   Graph->spliceFrom(LocGraph);
00218 
00219   Graph->setGlobalsGraph(GlobalsGraph);
00220   Graph->setPrintAuxCalls();
00221 
00222   // Start with a copy of the original call sites...
00223   Graph->getAuxFunctionCalls() = Graph->getFunctionCalls();
00224   return *Graph;
00225 }
00226 
00227 static bool isVAHackFn(const Function *F) {
00228   return F->getName() == "printf"  || F->getName() == "sscanf" ||
00229     F->getName() == "fprintf" || F->getName() == "open" ||
00230     F->getName() == "sprintf" || F->getName() == "fputs" ||
00231     F->getName() == "fscanf" || F->getName() == "malloc" ||
00232     F->getName() == "free";
00233 }
00234 
00235 static bool isResolvableFunc(const Function* callee) {
00236   return !callee->isExternal() || isVAHackFn(callee);
00237 }
00238 
00239 static void GetAllCallees(const DSCallSite &CS,
00240                           std::vector<Function*> &Callees) {
00241   if (CS.isDirectCall()) {
00242     if (isResolvableFunc(CS.getCalleeFunc()))
00243       Callees.push_back(CS.getCalleeFunc());
00244   } else if (!CS.getCalleeNode()->isIncomplete()) {
00245     // Get all callees.
00246     unsigned OldSize = Callees.size();
00247     CS.getCalleeNode()->addFullFunctionList(Callees);
00248 
00249     // If any of the callees are unresolvable, remove the whole batch!
00250     for (unsigned i = OldSize, e = Callees.size(); i != e; ++i)
00251       if (!isResolvableFunc(Callees[i])) {
00252         Callees.erase(Callees.begin()+OldSize, Callees.end());
00253         return;
00254       }
00255   }
00256 }
00257 
00258 
00259 /// GetAllAuxCallees - Return a list containing all of the resolvable callees in
00260 /// the aux list for the specified graph in the Callees vector.
00261 static void GetAllAuxCallees(DSGraph &G, std::vector<Function*> &Callees) {
00262   Callees.clear();
00263   for (DSGraph::afc_iterator I = G.afc_begin(), E = G.afc_end(); I != E; ++I)
00264     GetAllCallees(*I, Callees);
00265 }
00266 
00267 unsigned BUDataStructures::calculateGraphs(Function *F,
00268                                            std::vector<Function*> &Stack,
00269                                            unsigned &NextID,
00270                                      hash_map<Function*, unsigned> &ValMap) {
00271   assert(!ValMap.count(F) && "Shouldn't revisit functions!");
00272   unsigned Min = NextID++, MyID = Min;
00273   ValMap[F] = Min;
00274   Stack.push_back(F);
00275 
00276   // FIXME!  This test should be generalized to be any function that we have
00277   // already processed, in the case when there isn't a main or there are
00278   // unreachable functions!
00279   if (F->isExternal()) {   // sprintf, fprintf, sscanf, etc...
00280     // No callees!
00281     Stack.pop_back();
00282     ValMap[F] = ~0;
00283     return Min;
00284   }
00285 
00286   DSGraph &Graph = getOrCreateGraph(F);
00287 
00288   // Find all callee functions.
00289   std::vector<Function*> CalleeFunctions;
00290   GetAllAuxCallees(Graph, CalleeFunctions);
00291 
00292   // The edges out of the current node are the call site targets...
00293   for (unsigned i = 0, e = CalleeFunctions.size(); i != e; ++i) {
00294     Function *Callee = CalleeFunctions[i];
00295     unsigned M;
00296     // Have we visited the destination function yet?
00297     hash_map<Function*, unsigned>::iterator It = ValMap.find(Callee);
00298     if (It == ValMap.end())  // No, visit it now.
00299       M = calculateGraphs(Callee, Stack, NextID, ValMap);
00300     else                    // Yes, get it's number.
00301       M = It->second;
00302     if (M < Min) Min = M;
00303   }
00304 
00305   assert(ValMap[F] == MyID && "SCC construction assumption wrong!");
00306   if (Min != MyID)
00307     return Min;         // This is part of a larger SCC!
00308 
00309   // If this is a new SCC, process it now.
00310   if (Stack.back() == F) {           // Special case the single "SCC" case here.
00311     DEBUG(std::cerr << "Visiting single node SCC #: " << MyID << " fn: "
00312                     << F->getName() << "\n");
00313     Stack.pop_back();
00314     DSGraph &G = getDSGraph(*F);
00315     DEBUG(std::cerr << "  [BU] Calculating graph for: " << F->getName()<< "\n");
00316     calculateGraph(G);
00317     DEBUG(std::cerr << "  [BU] Done inlining: " << F->getName() << " ["
00318                     << G.getGraphSize() << "+" << G.getAuxFunctionCalls().size()
00319                     << "]\n");
00320 
00321     if (MaxSCC < 1) MaxSCC = 1;
00322 
00323     // Should we revisit the graph?  Only do it if there are now new resolvable
00324     // callees.
00325     GetAllAuxCallees(Graph, CalleeFunctions);
00326     if (!CalleeFunctions.empty()) {
00327       ValMap.erase(F);
00328       return calculateGraphs(F, Stack, NextID, ValMap);
00329     } else {
00330       ValMap[F] = ~0U;
00331     }
00332     return MyID;
00333 
00334   } else {
00335     // SCCFunctions - Keep track of the functions in the current SCC
00336     //
00337     std::vector<DSGraph*> SCCGraphs;
00338 
00339     unsigned SCCSize = 1;
00340     Function *NF = Stack.back();
00341     ValMap[NF] = ~0U;
00342     DSGraph &SCCGraph = getDSGraph(*NF);
00343 
00344     // First thing first, collapse all of the DSGraphs into a single graph for
00345     // the entire SCC.  Splice all of the graphs into one and discard all of the
00346     // old graphs.
00347     //
00348     while (NF != F) {
00349       Stack.pop_back();
00350       NF = Stack.back();
00351       ValMap[NF] = ~0U;
00352 
00353       DSGraph &NFG = getDSGraph(*NF);
00354 
00355       // Update the Function -> DSG map.
00356       for (DSGraph::retnodes_iterator I = NFG.retnodes_begin(),
00357              E = NFG.retnodes_end(); I != E; ++I)
00358         DSInfo[I->first] = &SCCGraph;
00359 
00360       SCCGraph.spliceFrom(NFG);
00361       delete &NFG;
00362 
00363       ++SCCSize;
00364     }
00365     Stack.pop_back();
00366 
00367     std::cerr << "Calculating graph for SCC #: " << MyID << " of size: "
00368               << SCCSize << "\n";
00369 
00370     // Compute the Max SCC Size.
00371     if (MaxSCC < SCCSize)
00372       MaxSCC = SCCSize;
00373 
00374     // Clean up the graph before we start inlining a bunch again...
00375     SCCGraph.removeDeadNodes(DSGraph::KeepUnreachableGlobals);
00376 
00377     // Now that we have one big happy family, resolve all of the call sites in
00378     // the graph...
00379     calculateGraph(SCCGraph);
00380     DEBUG(std::cerr << "  [BU] Done inlining SCC  [" << SCCGraph.getGraphSize()
00381                     << "+" << SCCGraph.getAuxFunctionCalls().size() << "]\n");
00382 
00383     std::cerr << "DONE with SCC #: " << MyID << "\n";
00384 
00385     // We never have to revisit "SCC" processed functions...
00386     return MyID;
00387   }
00388 
00389   return MyID;  // == Min
00390 }
00391 
00392 
00393 // releaseMemory - If the pass pipeline is done with this pass, we can release
00394 // our memory... here...
00395 //
00396 void BUDataStructures::releaseMyMemory() {
00397   for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
00398          E = DSInfo.end(); I != E; ++I) {
00399     I->second->getReturnNodes().erase(I->first);
00400     if (I->second->getReturnNodes().empty())
00401       delete I->second;
00402   }
00403 
00404   // Empty map so next time memory is released, data structures are not
00405   // re-deleted.
00406   DSInfo.clear();
00407   delete GlobalsGraph;
00408   GlobalsGraph = 0;
00409 }
00410 
00411 DSGraph &BUDataStructures::CreateGraphForExternalFunction(const Function &Fn) {
00412   Function *F = const_cast<Function*>(&Fn);
00413   DSGraph *DSG = new DSGraph(GlobalECs, GlobalsGraph->getTargetData());
00414   DSInfo[F] = DSG;
00415   DSG->setGlobalsGraph(GlobalsGraph);
00416   DSG->setPrintAuxCalls();
00417 
00418   // Add function to the graph.
00419   DSG->getReturnNodes().insert(std::make_pair(F, DSNodeHandle()));
00420 
00421   if (F->getName() == "free") { // Taking the address of free.
00422 
00423     // Free should take a single pointer argument, mark it as heap memory.
00424     DSNode *N = new DSNode(0, DSG);
00425     N->setHeapNodeMarker();
00426     DSG->getNodeForValue(F->arg_begin()).mergeWith(N);
00427 
00428   } else {
00429     std::cerr << "Unrecognized external function: " << F->getName() << "\n";
00430     abort();
00431   }
00432 
00433   return *DSG;
00434 }
00435 
00436 
00437 void BUDataStructures::calculateGraph(DSGraph &Graph) {
00438   // If this graph contains the main function, clone the globals graph into this
00439   // graph before we inline callees and other fun stuff.
00440   bool ContainsMain = false;
00441   DSGraph::ReturnNodesTy &ReturnNodes = Graph.getReturnNodes();
00442 
00443   for (DSGraph::ReturnNodesTy::iterator I = ReturnNodes.begin(),
00444          E = ReturnNodes.end(); I != E; ++I)
00445     if (I->first->hasExternalLinkage() && I->first->getName() == "main") {
00446       ContainsMain = true;
00447       break;
00448     }
00449 
00450   // If this graph contains main, copy the contents of the globals graph over.
00451   // Note that this is *required* for correctness.  If a callee contains a use
00452   // of a global, we have to make sure to link up nodes due to global-argument
00453   // bindings.
00454   if (ContainsMain) {
00455     const DSGraph &GG = *Graph.getGlobalsGraph();
00456     ReachabilityCloner RC(Graph, GG,
00457                           DSGraph::DontCloneCallNodes |
00458                           DSGraph::DontCloneAuxCallNodes);
00459 
00460     // Clone the global nodes into this graph.
00461     for (DSScalarMap::global_iterator I = GG.getScalarMap().global_begin(),
00462            E = GG.getScalarMap().global_end(); I != E; ++I)
00463       if (isa<GlobalVariable>(*I))
00464         RC.getClonedNH(GG.getNodeForValue(*I));
00465   }
00466 
00467 
00468   // Move our call site list into TempFCs so that inline call sites go into the
00469   // new call site list and doesn't invalidate our iterators!
00470   std::list<DSCallSite> TempFCs;
00471   std::list<DSCallSite> &AuxCallsList = Graph.getAuxFunctionCalls();
00472   TempFCs.swap(AuxCallsList);
00473 
00474   bool Printed = false;
00475   std::vector<Function*> CalledFuncs;
00476   while (!TempFCs.empty()) {
00477     DSCallSite &CS = *TempFCs.begin();
00478 
00479     CalledFuncs.clear();
00480 
00481     // Fast path for noop calls.  Note that we don't care about merging globals
00482     // in the callee with nodes in the caller here.
00483     if (CS.getRetVal().isNull() && CS.getNumPtrArgs() == 0) {
00484       TempFCs.erase(TempFCs.begin());
00485       continue;
00486     } else if (CS.isDirectCall() && isVAHackFn(CS.getCalleeFunc())) {
00487       TempFCs.erase(TempFCs.begin());
00488       continue;
00489     }
00490 
00491     GetAllCallees(CS, CalledFuncs);
00492 
00493     if (CalledFuncs.empty()) {
00494       // Remember that we could not resolve this yet!
00495       AuxCallsList.splice(AuxCallsList.end(), TempFCs, TempFCs.begin());
00496       continue;
00497     } else {
00498       DSGraph *GI;
00499       Instruction *TheCall = CS.getCallSite().getInstruction();
00500 
00501       if (CalledFuncs.size() == 1) {
00502         Function *Callee = CalledFuncs[0];
00503         ActualCallees.insert(std::make_pair(TheCall, Callee));
00504 
00505         // Get the data structure graph for the called function.
00506         GI = &getDSGraph(*Callee);  // Graph to inline
00507         DEBUG(std::cerr << "    Inlining graph for " << Callee->getName());
00508 
00509         DEBUG(std::cerr << "[" << GI->getGraphSize() << "+"
00510               << GI->getAuxFunctionCalls().size() << "] into '"
00511               << Graph.getFunctionNames() << "' [" << Graph.getGraphSize() <<"+"
00512               << Graph.getAuxFunctionCalls().size() << "]\n");
00513         Graph.mergeInGraph(CS, *Callee, *GI,
00514                            DSGraph::StripAllocaBit|DSGraph::DontCloneCallNodes);
00515         ++NumBUInlines;
00516       } else {
00517         if (!Printed)
00518           std::cerr << "In Fns: " << Graph.getFunctionNames() << "\n";
00519         std::cerr << "  calls " << CalledFuncs.size()
00520                   << " fns from site: " << CS.getCallSite().getInstruction()
00521                   << "  " << *CS.getCallSite().getInstruction();
00522         std::cerr << "   Fns =";
00523         unsigned NumPrinted = 0;
00524 
00525         for (std::vector<Function*>::iterator I = CalledFuncs.begin(),
00526                E = CalledFuncs.end(); I != E; ++I) {
00527           if (NumPrinted++ < 8) std::cerr << " " << (*I)->getName();
00528 
00529           // Add the call edges to the call graph.
00530           ActualCallees.insert(std::make_pair(TheCall, *I));
00531         }
00532         std::cerr << "\n";
00533 
00534         // See if we already computed a graph for this set of callees.
00535         std::sort(CalledFuncs.begin(), CalledFuncs.end());
00536         std::pair<DSGraph*, std::vector<DSNodeHandle> > &IndCallGraph =
00537           (*IndCallGraphMap)[CalledFuncs];
00538 
00539         if (IndCallGraph.first == 0) {
00540           std::vector<Function*>::iterator I = CalledFuncs.begin(),
00541             E = CalledFuncs.end();
00542 
00543           // Start with a copy of the first graph.
00544           GI = IndCallGraph.first = new DSGraph(getDSGraph(**I), GlobalECs);
00545           GI->setGlobalsGraph(Graph.getGlobalsGraph());
00546           std::vector<DSNodeHandle> &Args = IndCallGraph.second;
00547 
00548           // Get the argument nodes for the first callee.  The return value is
00549           // the 0th index in the vector.
00550           GI->getFunctionArgumentsForCall(*I, Args);
00551 
00552           // Merge all of the other callees into this graph.
00553           for (++I; I != E; ++I) {
00554             // If the graph already contains the nodes for the function, don't
00555             // bother merging it in again.
00556             if (!GI->containsFunction(*I)) {
00557               GI->cloneInto(getDSGraph(**I));
00558               ++NumBUInlines;
00559             }
00560 
00561             std::vector<DSNodeHandle> NextArgs;
00562             GI->getFunctionArgumentsForCall(*I, NextArgs);
00563             unsigned i = 0, e = Args.size();
00564             for (; i != e; ++i) {
00565               if (i == NextArgs.size()) break;
00566               Args[i].mergeWith(NextArgs[i]);
00567             }
00568             for (e = NextArgs.size(); i != e; ++i)
00569               Args.push_back(NextArgs[i]);
00570           }
00571 
00572           // Clean up the final graph!
00573           GI->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
00574         } else {
00575           std::cerr << "***\n*** RECYCLED GRAPH ***\n***\n";
00576         }
00577 
00578         GI = IndCallGraph.first;
00579 
00580         // Merge the unified graph into this graph now.
00581         DEBUG(std::cerr << "    Inlining multi callee graph "
00582               << "[" << GI->getGraphSize() << "+"
00583               << GI->getAuxFunctionCalls().size() << "] into '"
00584               << Graph.getFunctionNames() << "' [" << Graph.getGraphSize() <<"+"
00585               << Graph.getAuxFunctionCalls().size() << "]\n");
00586 
00587         Graph.mergeInGraph(CS, IndCallGraph.second, *GI,
00588                            DSGraph::StripAllocaBit |
00589                            DSGraph::DontCloneCallNodes);
00590         ++NumBUInlines;
00591       }
00592     }
00593     TempFCs.erase(TempFCs.begin());
00594   }
00595 
00596   // Recompute the Incomplete markers
00597   Graph.maskIncompleteMarkers();
00598   Graph.markIncompleteNodes(DSGraph::MarkFormalArgs);
00599 
00600   // Delete dead nodes.  Treat globals that are unreachable but that can
00601   // reach live nodes as live.
00602   Graph.removeDeadNodes(DSGraph::KeepUnreachableGlobals);
00603 
00604   // When this graph is finalized, clone the globals in the graph into the
00605   // globals graph to make sure it has everything, from all graphs.
00606   DSScalarMap &MainSM = Graph.getScalarMap();
00607   ReachabilityCloner RC(*GlobalsGraph, Graph, DSGraph::StripAllocaBit);
00608 
00609   // Clone everything reachable from globals in the function graph into the
00610   // globals graph.
00611   for (DSScalarMap::global_iterator I = MainSM.global_begin(),
00612          E = MainSM.global_end(); I != E; ++I)
00613     RC.getClonedNH(MainSM[*I]);
00614 
00615   //Graph.writeGraphToFile(std::cerr, "bu_" + F.getName());
00616 }
00617 
00618 static const Function *getFnForValue(const Value *V) {
00619   if (const Instruction *I = dyn_cast<Instruction>(V))
00620     return I->getParent()->getParent();
00621   else if (const Argument *A = dyn_cast<Argument>(V))
00622     return A->getParent();
00623   else if (const BasicBlock *BB = dyn_cast<BasicBlock>(V))
00624     return BB->getParent();
00625   return 0;
00626 }
00627 
00628 /// deleteValue/copyValue - Interfaces to update the DSGraphs in the program.
00629 /// These correspond to the interfaces defined in the AliasAnalysis class.
00630 void BUDataStructures::deleteValue(Value *V) {
00631   if (const Function *F = getFnForValue(V)) {  // Function local value?
00632     // If this is a function local value, just delete it from the scalar map!
00633     getDSGraph(*F).getScalarMap().eraseIfExists(V);
00634     return;
00635   }
00636 
00637   if (Function *F = dyn_cast<Function>(V)) {
00638     assert(getDSGraph(*F).getReturnNodes().size() == 1 &&
00639            "cannot handle scc's");
00640     delete DSInfo[F];
00641     DSInfo.erase(F);
00642     return;
00643   }
00644 
00645   assert(!isa<GlobalVariable>(V) && "Do not know how to delete GV's yet!");
00646 }
00647 
00648 void BUDataStructures::copyValue(Value *From, Value *To) {
00649   if (From == To) return;
00650   if (const Function *F = getFnForValue(From)) {  // Function local value?
00651     // If this is a function local value, just delete it from the scalar map!
00652     getDSGraph(*F).getScalarMap().copyScalarIfExists(From, To);
00653     return;
00654   }
00655 
00656   if (Function *FromF = dyn_cast<Function>(From)) {
00657     Function *ToF = cast<Function>(To);
00658     assert(!DSInfo.count(ToF) && "New Function already exists!");
00659     DSGraph *NG = new DSGraph(getDSGraph(*FromF), GlobalECs);
00660     DSInfo[ToF] = NG;
00661     assert(NG->getReturnNodes().size() == 1 && "Cannot copy SCC's yet!");
00662 
00663     // Change the Function* is the returnnodes map to the ToF.
00664     DSNodeHandle Ret = NG->retnodes_begin()->second;
00665     NG->getReturnNodes().clear();
00666     NG->getReturnNodes()[ToF] = Ret;
00667     return;
00668   }
00669 
00670   if (const Function *F = getFnForValue(To)) {
00671     DSGraph &G = getDSGraph(*F);
00672     G.getScalarMap().copyScalarIfExists(From, To);
00673     return;
00674   }
00675 
00676   std::cerr << *From;
00677   std::cerr << *To;
00678   assert(0 && "Do not know how to copy this yet!");
00679   abort();
00680 }