C++ DSGraph::computeIntPtrFlags方法代码示例

// BU:
// Construct the callgraph from the local graphs
// Find SCCs
// inline bottom up
//
bool BUDataStructures::runOnModuleInternal(Module& M) {

  //
  // Make sure we have a DSGraph for all declared functions in the Module.
  // While we may not need them in this DSA pass, a later DSA pass may ask us
  // for their DSGraphs, and we want to have them if asked.
  //
  for (Function &F : M) {
    if (!(F.isDeclaration())){
      getOrCreateGraph(&F);
    }
  }

  //
  // Do a post-order traversal of the SCC callgraph and do bottom-up inlining.
  //
  postOrderInline (M);

  // 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);
  GlobalsGraph->computeExternalFlags(DSGraph::DontMarkFormalsExternal);
  GlobalsGraph->computeIntPtrFlags();

  //
  // Create equivalence classes for aliasing globals so that we only need to
  // record one global per DSNode.
  //
  formGlobalECs();

  // Merge the globals variables (not the calls) from the globals graph back
  // into the individual function's graph so that changes made to globals during
  // BU can be reflected. This is specifically needed for correct call graph
  //
  for (Function &F : M) {
    if (!(F.isDeclaration())){
      DSGraph *Graph  = getOrCreateGraph(&F);
      cloneGlobalsInto(Graph, DSGraph::DontCloneCallNodes |
                        DSGraph::DontCloneAuxCallNodes);
      Graph->buildCallGraph(callgraph, GlobalFunctionList, filterCallees);
      Graph->maskIncompleteMarkers();
      Graph->markIncompleteNodes(DSGraph::MarkFormalArgs |
                                   DSGraph::IgnoreGlobals);
      Graph->computeExternalFlags(DSGraph::DontMarkFormalsExternal);
      Graph->computeIntPtrFlags();
    }
  }

  // Once the correct flags have been calculated. Update the callgraph.
  for (Function &F : M) {
    if (!(F.isDeclaration())){
      DSGraph *Graph = getOrCreateGraph(&F);
      Graph->buildCompleteCallGraph(callgraph,
                                    GlobalFunctionList, filterCallees);
    }
  }

  NumCallEdges += callgraph.size();

  // Put the call graph in canonical form
  callgraph.buildSCCs();
  callgraph.buildRoots();

  DEBUG(print(errs(), &M));
  return false;
}

// run - Calculate the top down data structure graphs for each function in the
// program.
//
bool TDDataStructures::runOnModule(Module &M) {

  init(useEQBU ? &getAnalysis<EquivBUDataStructures>()
       : &getAnalysis<BUDataStructures>(),
       true, true, true, false);
  // Figure out which functions must not mark their arguments complete because
  // they are accessible outside this compilation unit.  Currently, these
  // arguments are functions which are reachable by incomplete or external
  // nodes in the globals graph.
  const DSScalarMap &GGSM = GlobalsGraph->getScalarMap();
  DenseSet<DSNode*> Visited;
  for (DSScalarMap::global_iterator I=GGSM.global_begin(), E=GGSM.global_end();
       I != E; ++I) {
    DSNode *N = GGSM.find(*I)->second.getNode();
    if (N->isIncompleteNode() || N->isExternalNode())
      markReachableFunctionsExternallyAccessible(N, Visited);
  }

  // Loop over unresolved call nodes.  Any functions passed into (but not
  // returned!) from unresolvable call nodes may be invoked outside of the
  // current module.
  for (DSGraph::afc_iterator I = GlobalsGraph->afc_begin(),
         E = GlobalsGraph->afc_end(); I != E; ++I)
    for (unsigned arg = 0, e = I->getNumPtrArgs(); arg != e; ++arg)
      markReachableFunctionsExternallyAccessible(I->getPtrArg(arg).getNode(),
                                                 Visited);
  Visited.clear();

  // Clear Aux of Globals Graph to be refilled in later by post-TD unresolved
  // functions
  GlobalsGraph->getAuxFunctionCalls().clear();

  // Functions without internal linkage are definitely externally callable!
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
    if (!I->isDeclaration() && !I->hasInternalLinkage() && !I->hasPrivateLinkage())
      ExternallyCallable.insert(I);

  // Debug code to print the functions that are externally callable
#if 0
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
    if (ExternallyCallable.count(I)) {
      errs() << "ExternallyCallable: " << I->getNameStr() << "\n";
    }
#endif

  // We want to traverse the call graph in reverse post-order.  To do this, we
  // calculate a post-order traversal, then reverse it.
  DenseSet<DSGraph*> VisitedGraph;
  std::vector<DSGraph*> PostOrder;

{TIME_REGION(XXX, "td:Compute postorder");

  // Calculate top-down from main...
  if (Function *F = M.getFunction("main"))
    ComputePostOrder(*F, VisitedGraph, PostOrder);

  // Next calculate the graphs for each unreachable function...
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
    if (!I->isDeclaration())
      ComputePostOrder(*I, VisitedGraph, PostOrder);

  VisitedGraph.clear();   // Release memory!
}

{TIME_REGION(XXX, "td:Inline stuff");

  // Visit each of the graphs in reverse post-order now!
  while (!PostOrder.empty()) {
    InlineCallersIntoGraph(PostOrder.back());
    PostOrder.pop_back();
  }
}

  // Free the IndCallMap.
  while (!IndCallMap.empty()) {
    delete IndCallMap.begin()->second;
    IndCallMap.erase(IndCallMap.begin());
  }

  formGlobalECs();

  ExternallyCallable.clear();
  GlobalsGraph->removeTriviallyDeadNodes();
  GlobalsGraph->computeExternalFlags(DSGraph::DontMarkFormalsExternal);
  GlobalsGraph->computeIntPtrFlags();

  // Make sure each graph has updated external information about globals
  // in the globals graph.
  VisitedGraph.clear();
  for (Module::iterator F = M.begin(); F != M.end(); ++F) {
    if (!(F->isDeclaration())){
      DSGraph *Graph  = getOrCreateGraph(F);
      if (!VisitedGraph.insert(Graph).second) continue;

      cloneGlobalsInto(Graph, DSGraph::DontCloneCallNodes |
                        DSGraph::DontCloneAuxCallNodes);

//.........这里部分代码省略.........

//
// Method: postOrderInline()
//
// Description:
//  This methods does a post order traversal of the call graph and performs
//  bottom-up inlining of the DSGraphs.
//
void
BUDataStructures::postOrderInline (Module & M) {
  // Variables used for Tarjan SCC-finding algorithm.  These are passed into
  // the recursive function used to find SCCs.
  std::vector<const Function*> Stack;
  std::map<const Function*, unsigned> ValMap;
  unsigned NextID = 1;


  // Do post order traversal on the global ctors. Use this information to update
  // the globals graph.
  const char *Name = "llvm.global_ctors";
  GlobalVariable *GV = M.getNamedGlobal(Name);
  if (GV && !(GV->isDeclaration()) && !(GV->hasLocalLinkage())) {
    // Should be an array of '{ int, void ()* }' structs.  The first value is
    // the init priority, which we ignore.
    ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
    if (InitList) {
      for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i)
        if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))) {
          if (CS->getNumOperands() != 2)
            break; // Not array of 2-element structs.
          Constant *FP = CS->getOperand(1);
          if (FP->isNullValue())
            break;  // Found a null terminator, exit.

          if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
            if (CE->isCast())
              FP = CE->getOperand(0);
          Function *F = dyn_cast<Function>(FP);
          if (F && !F->isDeclaration() && !ValMap.count(F)) {
            calculateGraphs(F, Stack, NextID, ValMap);
            CloneAuxIntoGlobal(getDSGraph(*F));
          }
        }
      GlobalsGraph->removeTriviallyDeadNodes();
      GlobalsGraph->maskIncompleteMarkers();

      // Mark external globals incomplete.
      GlobalsGraph->markIncompleteNodes(DSGraph::IgnoreGlobals);
      GlobalsGraph->computeExternalFlags(DSGraph::DontMarkFormalsExternal);
      GlobalsGraph->computeIntPtrFlags();

      //
      // Create equivalence classes for aliasing globals so that we only need to
      // record one global per DSNode.
      //
      formGlobalECs();
      // propogte information calculated
      // from the globals graph to the other graphs.
      for (Module::iterator F = M.begin(); F != M.end(); ++F) {
        if (!(F->isDeclaration())){
          DSGraph *Graph  = getDSGraph(*F);
          cloneGlobalsInto(Graph, DSGraph::DontCloneCallNodes |
                           DSGraph::DontCloneAuxCallNodes);
          Graph->buildCallGraph(callgraph, GlobalFunctionList, filterCallees);
          Graph->maskIncompleteMarkers();
          Graph->markIncompleteNodes(DSGraph::MarkFormalArgs |
                                     DSGraph::IgnoreGlobals);
          Graph->computeExternalFlags(DSGraph::DontMarkFormalsExternal);
          Graph->computeIntPtrFlags();
        }
      }
    }
  }

  //
  // Start the post order traversal with the main() function.  If there is no
  // main() function, don't worry; we'll have a separate traversal for inlining
  // graphs for functions not reachable from main().
  //
  Function *MainFunc = M.getFunction ("main");
  if (MainFunc && !MainFunc->isDeclaration()) {
    calculateGraphs(MainFunc, Stack, NextID, ValMap);
    CloneAuxIntoGlobal(getDSGraph(*MainFunc));
  }

  //
  // Calculate the graphs for any functions that are unreachable from main...
  //
  for (Function &F : M)
    if (!F.isDeclaration() && !ValMap.count(&F)) {
      if (MainFunc)
        DEBUG(errs() << debugname << ": Function unreachable from main: "
        << F.getName() << "\n");
      calculateGraphs(&F, Stack, NextID, ValMap);     // Calculate all graphs.
      CloneAuxIntoGlobal(getDSGraph(F));

      // Mark this graph as processed.  Do this by finding all functions
      // in the graph that map to it, and mark them visited.
      // Note that this really should be handled neatly by calculateGraphs
      // itself, not here.  However this catches the worst offenders.
      DSGraph *G = getDSGraph(F);
//.........这里部分代码省略.........