//
// Method: calculateGraphs()
//
// Description:
//  Perform recursive bottom-up inlining of DSGraphs from callee to caller.
//
// Inputs:
//  F - The function which should have its callees' DSGraphs merged into its
//      own DSGraph.
//  Stack - The stack used for Tarjan's SCC-finding algorithm.
//  NextID - The nextID value used for Tarjan's SCC-finding algorithm.
//  ValMap - The map used for Tarjan's SCC-finding algorithm.
//
// Return value:
//
unsigned
BUDataStructures::calculateGraphs (const Function *F,
                                   TarjanStack & Stack,
                                   unsigned & NextID,
                                   TarjanMap & 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->isDeclaration()) {   // sprintf, fprintf, sscanf, etc...
    // No callees!
    Stack.pop_back();
    ValMap[F] = ~0;
    return Min;
  }

  //
  // Get the DSGraph of the current function.  Make one if one doesn't exist.
  //
  DSGraph* Graph = getOrCreateGraph(F);

  //
  // Find all callee functions.  Use the DSGraph for this (do not use the call
  // graph (DSCallgraph) as we're still in the process of constructing it).
  //
  FuncSet CalleeFunctions;
  getAllAuxCallees(Graph, CalleeFunctions);

  //
  // Iterate through each call target (these are the edges out of the current
  // node (i.e., the current function) in Tarjan graph parlance).  Find the
  // minimum assigned ID.
  //
  for (FuncSet::iterator I = CalleeFunctions.begin(), E = CalleeFunctions.end();
       I != E; ++I) {
    const Function *Callee = *I;
    unsigned M;
    //
    // If we have not visited this callee before, visit it now (this is the
    // post-order component of the Bottom-Up algorithm).  Otherwise, look up
    // the assigned ID value from the Tarjan Value Map.
    //
    TarjanMap::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 we've found a function with a smaller ID than this funtion, record
    // that ID as the minimum ID.
    //
    if (M < Min) Min = M;
  }

  assert(ValMap[F] == MyID && "SCC construction assumption wrong!");

  //
  // If the minimum ID found is not this function's ID, then this function is
  // part of a larger SCC.
  //
  if (Min != MyID)
    return Min;

  //
  // If this is a new SCC, process it now.
  //
  if (Stack.back() == F) {           // Special case the single "SCC" case here.
    DEBUG(errs() << "Visiting single node SCC #: " << MyID << " fn: "
	  << F->getName() << "\n");
    Stack.pop_back();
    DEBUG(errs() << "  [BU] Calculating graph for: " << F->getName()<< "\n");
    DSGraph* G = getOrCreateGraph(F);
    calculateGraph(G);
    DEBUG(errs() << "  [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.
    FuncSet NewCallees;
    getAllAuxCallees(G, NewCallees);
    if (!NewCallees.empty()) {
      if (hasNewCallees(NewCallees, CalleeFunctions)) {
        DEBUG(errs() << "Recalculating " << F->getName() << " due to new knowledge\n");
        ValMap.erase(F);
        ++NumRecalculations;
        return calculateGraphs(F, Stack, NextID, ValMap);
      }
      ++NumRecalculationsSkipped;
    }
    ValMap[F] = ~0U;
    return MyID;
  } else {
    unsigned SCCSize = 1;
    const Function *NF = Stack.back();
    if(NF != F)
      ValMap[NF] = ~0U;
    DSGraph* SCCGraph = getDSGraph(*NF);

    //
    // First thing first: collapse all of the DSGraphs into a single graph for
    // the entire SCC.  Splice all of the graphs into one and discard all of
    // the old graphs.
    //
    while (NF != F) {
      Stack.pop_back();
      NF = Stack.back();
      if(NF != F)
        ValMap[NF] = ~0U;

      DSGraph* NFG = getDSGraph(*NF);

      if (NFG != SCCGraph) {
        // Update the Function -> DSG map.
        for (DSGraph::retnodes_iterator I = NFG->retnodes_begin(),
               E = NFG->retnodes_end(); I != E; ++I)
          setDSGraph(*I->first, SCCGraph);

        SCCGraph->spliceFrom(NFG);
        delete NFG;
        ++SCCSize;
      }
    }
    Stack.pop_back();

    DEBUG(errs() << "Calculating graph for SCC #: " << MyID << " of size: "
	  << SCCSize << "\n");

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

    // 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(errs() << "  [BU] Done inlining SCC  [" << SCCGraph->getGraphSize()
	  << "+" << SCCGraph->getAuxFunctionCalls().size() << "]\n"
	  << "DONE with SCC #: " << MyID << "\n");
    FuncSet NewCallees;
    getAllAuxCallees(SCCGraph, NewCallees);
    if (!NewCallees.empty()) {
      if (hasNewCallees(NewCallees, CalleeFunctions)) {
        DEBUG(errs() << "Recalculating SCC Graph " << F->getName() << " due to new knowledge\n");
        ValMap.erase(F);
        ++NumRecalculations;
        return calculateGraphs(F, Stack, NextID, ValMap);
      }
      ++NumRecalculationsSkipped;
    }
    ValMap[F] = ~0U;
    return MyID;
  }
}
Exemple #2
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unsigned BUDataStructures::calculateGraphs(const Function *F,
                                           std::vector<const Function*> &Stack,
                                           unsigned &NextID,
                                           hash_map<const 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->isDeclaration()) {   // sprintf, fprintf, sscanf, etc...
    // No callees!
    Stack.pop_back();
    ValMap[F] = ~0;
    return Min;
  }

  DSGraph* Graph = getOrFetchDSGraph(F);

  // Find all callee functions.
  std::vector<const Function*> CalleeFunctions;
  GetAllAuxCallees(Graph, CalleeFunctions);
  std::sort(CalleeFunctions.begin(), CalleeFunctions.end());
  std::vector<const Function*>::iterator uid = std::unique(CalleeFunctions.begin(), CalleeFunctions.end());
  CalleeFunctions.resize(uid - CalleeFunctions.begin());

  // The edges out of the current node are the call site targets...
  for (unsigned i = 0, e = CalleeFunctions.size(); i != e; ++i) {
    const Function *Callee = CalleeFunctions[i];
    unsigned M;
    // Have we visited the destination function yet?
    hash_map<const 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(errs() << "Visiting single node SCC #: " << MyID << " fn: "
	  << F->getName() << "\n");
    Stack.pop_back();
    DEBUG(errs() << "  [BU] Calculating graph for: " << F->getName()<< "\n");
    calculateGraph(Graph);
    DEBUG(errs() << "  [BU] Done inlining: " << F->getName() << " ["
	  << Graph->getGraphSize() << "+" << Graph->getAuxFunctionCalls().size()
	  << "]\n");

    if (MaxSCC < 1) MaxSCC = 1;

    // Should we revisit the graph?  Only do it if there are now new resolvable
    // callees or new callees
    GetAllAuxCallees(Graph, CalleeFunctions);
    if (CalleeFunctions.size()) {
      DEBUG(errs() << "Recalculating " << F->getName() << " due to new knowledge\n");
      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
    //
    std::vector<DSGraph*> SCCGraphs;

    unsigned SCCSize = 1;
    const Function *NF = Stack.back();
    ValMap[NF] = ~0U;
    DSGraph* SCCGraph = getDSGraph(NF);

    // First thing first, collapse all of the DSGraphs into a single graph for
    // the entire SCC.  Splice all of the graphs into one and discard all of the
    // old graphs.
    //
    while (NF != F) {
      Stack.pop_back();
      NF = Stack.back();
      ValMap[NF] = ~0U;

      DSGraph* NFG = getDSGraph(NF);

      if (NFG != SCCGraph) {
        // Update the Function -> DSG map.
        for (DSGraph::retnodes_iterator I = NFG->retnodes_begin(),
               E = NFG->retnodes_end(); I != E; ++I)
          setDSGraph(I->first, SCCGraph);
        
        SCCGraph->spliceFrom(NFG);
        delete NFG;
        ++SCCSize;
      }
    }
    Stack.pop_back();

    DEBUG(errs() << "Calculating graph for SCC #: " << MyID << " of size: "
	  << SCCSize << "\n");

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

    // 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(errs() << "  [BU] Done inlining SCC  [" << SCCGraph->getGraphSize()
	  << "+" << SCCGraph->getAuxFunctionCalls().size() << "]\n"
	  << "DONE with SCC #: " << MyID << "\n");

    // We never have to revisit "SCC" processed functions...
    return MyID;
  }

  return MyID;  // == Min
}