C++ DSNodeHandle类代码示例

void GraphBuilder::mergeInGlobalInitializer(GlobalVariable *GV) {
  // Ensure that the global variable is not external
  assert(!GV->isDeclaration() && "Cannot merge in external global!");

  //
  // Get a node handle to the global node and merge the initializer into it.
  //
  DSNodeHandle NH = getValueDest(GV);

  //
  // Ensure that the DSNode is large enough to hold the new constant that we'll
  // be adding to it.
  //
  Type * ElementType = GV->getType()->getElementType();
  while(ArrayType *ATy = dyn_cast<ArrayType>(ElementType)) {
    ElementType = ATy->getElementType();
  }
  if(!NH.getNode()->isNodeCompletelyFolded()) {
    unsigned requiredSize = TD.getTypeAllocSize(ElementType) + NH.getOffset();
    if (NH.getNode()->getSize() < requiredSize){
      NH.getNode()->growSize (requiredSize);
    }
  }

  //
  // Do the actual merging in of the constant initializer.
  //
  MergeConstantInitIntoNode(NH, GV->getType()->getElementType(), GV->getInitializer());

}

void DSMonitor::witness(DSNodeHandle N, std::vector<Value*> VS, std::string M) {
  if (N.isNull() || N.getNode()->isCollapsedNode())
    return;

  watch(N,VS,M);
  check();
}

// Method: getDSNodeHandle()
//
// Description:
//  This method looks up the DSNodeHandle for a given LLVM value.  The context
//  of the value is the specified function, although if it is a global value,
//  the DSNodeHandle may exist within the global DSGraph.
//
// Return value:
//  A DSNodeHandle for the value is returned.  This DSNodeHandle could either
//  be in the function's DSGraph or from the GlobalsGraph.  Note that the
//  DSNodeHandle may represent a NULL DSNode.
//
template<class dsa> DSNodeHandle
TypeSafety<dsa>::getDSNodeHandle (const Value * V, const Function * F) {
  //
  // Ensure that the function has a DSGraph
  //
  assert (dsaPass->hasDSGraph(*F) && "No DSGraph for function!\n");

  //
  // Lookup the DSNode for the value in the function's DSGraph.
  //
  const DSGraph * TDG = dsaPass->getDSGraph(*F);

  DSNodeHandle DSH;
  if(TDG->hasNodeForValue(V))
    DSH = TDG->getNodeForValue(V);

  //
  // If the value wasn't found in the function's DSGraph, then maybe we can
  // find the value in the globals graph.
  //
  if ((DSH.isNull()) && (isa<GlobalValue>(V))) {
    //
    // Try looking up this DSNode value in the globals graph.  Note that
    // globals are put into equivalence classes; we may need to first find the
    // equivalence class to which our global belongs, find the global that
    // represents all globals in that equivalence class, and then look up the
    // DSNode Handle for *that* global.
    //
    DSH = getDSNodeHandle(cast<GlobalValue>(V));
  }
  return DSH;
}

// Method: getDSNodeHandle()
//
// Description:
//  This method looks up the DSNodeHandle for a given LLVM globalvalue. 
//  The value is looked up in the globals graph
//
// Return value:
//  A DSNodeHandle for the value is returned.  This DSNodeHandle is from 
//  the GlobalsGraph.  Note that the DSNodeHandle may represent a NULL DSNode.
//
template<class dsa> DSNodeHandle
TypeSafety<dsa>::getDSNodeHandle(const GlobalValue *V) {
  DSNodeHandle DSH;
  const DSGraph * GlobalsGraph = dsaPass->getGlobalsGraph ();
  if(GlobalsGraph->hasNodeForValue(V)) {
    DSH = GlobalsGraph->getNodeForValue(V);
  }
  //
  // Try looking up this DSNode value in the globals graph.  Note that
  // globals are put into equivalence classes; we may need to first find the
  // equivalence class to which our global belongs, find the global that
  // represents all globals in that equivalence class, and then look up the
  // DSNode Handle for *that* global.
  //
  if (DSH.isNull()) {
    //
    // DSA does not currently handle global aliases.
    //
    if (!isa<GlobalAlias>(V)) {
      //
      // We have to dig into the globalEC of the DSGraph to find the DSNode.
      //
      const GlobalValue * GV = dyn_cast<GlobalValue>(V);
      const GlobalValue * Leader;
      Leader = GlobalsGraph->getGlobalECs().getLeaderValue(GV);
      DSH = GlobalsGraph->getNodeForValue(Leader);
    }
  }
  return DSH;
}

void GraphBuilder::visitInsertValueInst(InsertValueInst& I) {
  setDestTo(I, createNode()->setAllocaMarker());

  Type *StoredTy = I.getInsertedValueOperand()->getType();
  DSNodeHandle Dest = getValueDest(&I);
  Dest.mergeWith(getValueDest(I.getAggregateOperand()));

  // Mark that the node is written to...
  Dest.getNode()->setModifiedMarker();
  unsigned Offset = 0;
  Type* STy = I.getAggregateOperand()->getType();
  llvm::InsertValueInst::idx_iterator i = I.idx_begin(), e = I.idx_end(); 
  for (; i != e; i++) {
    const StructLayout *SL = TD.getStructLayout(cast<StructType>(STy));
    Offset += SL->getElementOffset(*i);
    STy = (cast<StructType>(STy))->getTypeAtIndex(*i);
  }

  // Ensure a type-record exists...
  Dest.getNode()->mergeTypeInfo(StoredTy, Offset); 

  // Avoid adding edges from null, or processing non-"pointer" stores
  if (isa<PointerType>(StoredTy))
    Dest.addEdgeTo(getValueDest(I.getInsertedValueOperand()));
}

void GraphBuilder::visitVAStartInst(CallSite CS) {
  // Build out DSNodes for the va_list depending on the target arch
  // And assosiate the right node with the VANode for this function
  // so it can be merged with the right arguments from callsites

  DSNodeHandle RetNH = getValueDest(*CS.arg_begin());

  if (DSNode *N = RetNH.getNode())
    visitVAStartNode(N);
}

void
PoolRegisterElimination::removeTypeSafeRegistrations (const char * name) {
  //
  // Scan through all uses of the registration function and see if it can be
  // safely removed.  If so, schedule it for removal.
  //
  std::vector<CallInst*> toBeRemoved;
  Function * F = intrinsic->getIntrinsic(name).F;

  //
  // Look for and record all registrations that can be deleted.
  //
  for (Value::use_iterator UI=F->use_begin(), UE=F->use_end();
       UI != UE;
       ++UI) {
    //
    // Get the pointer to the registered object.
    //
    CallInst * CI = cast<CallInst>(*UI);
    Value * Ptr = intrinsic->getValuePointer(CI);
    // Lookup the DSNode for the value in the function's DSGraph.
    //
    DSGraph * TDG = dsaPass->getDSGraph(*(CI->getParent()->getParent()));
    DSNodeHandle DSH = TDG->getNodeForValue(Ptr);
    assert ((!(DSH.isNull())) && "No DSNode for Value!\n");

    //
    // If the DSNode is type-safe and is never used as an array, then there
    // will never be a need to look it up in a splay tree, so remove its
    // registration.
    //
    DSNode * N = DSH.getNode();
    if(!N->isArrayNode() && 
       TS->isTypeSafe(Ptr, F)){
      toBeRemoved.push_back(CI);
    }
  }

  //
  // Update the statistics.
  //
  if (toBeRemoved.size()) {
    RemovedRegistration += toBeRemoved.size();
    TypeSafeRegistrations += toBeRemoved.size();
  }

  //
  // Remove the unnecesary registrations.
  //
  std::vector<CallInst*>::iterator it, end;
  for (it = toBeRemoved.begin(), end = toBeRemoved.end(); it != end; ++it) {
    (*it)->eraseFromParent();
  }
}

// visitInstruction - For all other instruction types, if we have any arguments
// that are of pointer type, make them have unknown composition bits, and merge
// the nodes together.
void GraphBuilder::visitInstruction(Instruction &Inst) {
  DSNodeHandle CurNode;
  if (isa<PointerType>(Inst.getType()))
    CurNode = getValueDest(&Inst);
  for (User::op_iterator I = Inst.op_begin(), E = Inst.op_end(); I != E; ++I)
    if (isa<PointerType>((*I)->getType()))
      CurNode.mergeWith(getValueDest(*I));

  if (DSNode *N = CurNode.getNode())
    N->setUnknownMarker();
}

bool DSGraphStats::isNodeForValueUntyped(Value *V, unsigned Offset, const Function *F) {
  DSNodeHandle NH = getNodeHandleForValue(V);
  if(!NH.getNode()){
    return true;
  }
  else {
    DSNode *N = NH.getNode();
    if (N->isNodeCompletelyFolded()){
      ++NumFoldedAccess;
      return true;
    }
    if ( N->isExternalNode()){
      ++NumExternalAccesses;
      return true;
    }
    if ( N->isIncompleteNode()){
      ++NumIncompleteAccesses;
      return true;
    }
    if (N->isUnknownNode()){
      ++NumUnknownAccesses;
      return true;
    }
    if (N->isIntToPtrNode()){
      ++NumI2PAccesses;
      return true;
    }
    // it is a complete node, now check how many types are present
    int count = 0;
    unsigned offset = NH.getOffset() + Offset;
    if (N->type_begin() != N->type_end())
      for (DSNode::TyMapTy::const_iterator ii = N->type_begin(),
           ee = N->type_end(); ii != ee; ++ii) {
        if(ii->first != offset)
          continue;
        count += ii->second->size();
      }

    if (count ==0)
      ++NumTypeCount0Accesses;
    else if(count == 1)
      ++NumTypeCount1Accesses;
    else if(count == 2)
      ++NumTypeCount2Accesses;
    else if(count == 3)
      ++NumTypeCount3Accesses;
    else
      ++NumTypeCount4Accesses;
    DEBUG(assert(TS->isTypeSafe(V,F)));
  }
  return false;
}

//
// Method: getDSNodeHandle()
//
// Description:
//  This method looks up the DSNodeHandle for a given LLVM value.  The context
//  of the value is the specified function, although if it is a global value,
//  the DSNodeHandle may exist within the global DSGraph.
//
// Return value:
//  A DSNodeHandle for the value is returned.  This DSNodeHandle could either
//  be in the function's DSGraph or from the GlobalsGraph.  Note that the
//  DSNodeHandle may represent a NULL DSNode.
//
DSNodeHandle
CompleteChecks::getDSNodeHandle (const Value * V, const Function * F) {
  //
  // Get access to the points-to results.
  //
  EQTDDataStructures & dsaPass = getAnalysis<EQTDDataStructures>();

  //
  // Ensure that the function has a DSGraph
  //
  assert (dsaPass.hasDSGraph(*F) && "No DSGraph for function!\n");

  //
  // Lookup the DSNode for the value in the function's DSGraph.
  //
  DSGraph * TDG = dsaPass.getDSGraph(*F);
  DSNodeHandle DSH = TDG->getNodeForValue(V);

  //
  // If the value wasn't found in the function's DSGraph, then maybe we can
  // find the value in the globals graph.
  //
  if ((DSH.isNull()) && (isa<GlobalValue>(V))) {
    //
    // Try looking up this DSNode value in the globals graph.  Note that
    // globals are put into equivalence classes; we may need to first find the
    // equivalence class to which our global belongs, find the global that
    // represents all globals in that equivalence class, and then look up the
    // DSNode Handle for *that* global.
    //
    DSGraph * GlobalsGraph = TDG->getGlobalsGraph ();
    DSH = GlobalsGraph->getNodeForValue(V);
    if (DSH.isNull()) {
      //
      // DSA does not currently handle global aliases.
      //
      if (!isa<GlobalAlias>(V)) {
        //
        // We have to dig into the globalEC of the DSGraph to find the DSNode.
        //
        const GlobalValue * GV = dyn_cast<GlobalValue>(V);
        const GlobalValue * Leader;
        Leader = GlobalsGraph->getGlobalECs().getLeaderValue(GV);
        DSH = GlobalsGraph->getNodeForValue(Leader);
      }
    }
  }

  return DSH;
}

void GraphBuilder::visitVAArgInst(VAArgInst &I) {
  Module *M = FB->getParent();
  Triple TargetTriple(M->getTargetTriple());
  Triple::ArchType Arch = TargetTriple.getArch();
  switch(Arch) {
  case Triple::x86_64: {
    // On x86_64, we have va_list as a struct {i32, i32, i8*, i8* }
    // The first i8* is where arguments generally go, but the second i8* can
    // be used also to pass arguments by register.
    // We model this by having both the i8*'s point to an array of pointers
    // to the arguments.
    DSNodeHandle Ptr = G.getVANodeFor(*FB);
    DSNodeHandle Dest = getValueDest(&I);
    if (Ptr.isNull()) return;

    // Make that the node is read and written
    Ptr.getNode()->setReadMarker()->setModifiedMarker();

    // Not updating type info, as it is already a collapsed node

    if (isa<PointerType>(I.getType()))
      Dest.mergeWith(Ptr);
    return; 
  }

  default: {
    assert(0 && "What frontend generates this?");
    DSNodeHandle Ptr = getValueDest(I.getOperand(0));

    //FIXME: also updates the argument
    if (Ptr.isNull()) return;

    // Make that the node is read and written
    Ptr.getNode()->setReadMarker()->setModifiedMarker();

    // Ensure a type record exists.
    DSNode *PtrN = Ptr.getNode();
    PtrN->mergeTypeInfo(I.getType(), Ptr.getOffset());

    if (isa<PointerType>(I.getType()))
      setDestTo(I, getLink(Ptr));
  }
  }
}

//
// TODO
//
template<class dsa> bool
TypeSafety<dsa>::isFieldDisjoint (const GlobalValue * V, unsigned offset) {
  //
  // Get the DSNode for the specified value.
  //
  DSNodeHandle DH = getDSNodeHandle (V);
  DSNode *node = DH.getNode();
  //unsigned offset = DH.getOffset();
  DEBUG(errs() << " check fields overlap at: " << offset << "\n");

  //
  // If there is no DSNode, claim that it is not type safe.
  //
  if (DH.isNull()) {
    return false;
  }
  //
  // If the DSNode is completely folded, then we know for sure that it is not
  // type-safe.
  //
  if (node->isNodeCompletelyFolded())
    return false;

  //
  // If the memory object represented by this DSNode can be manipulated by
  // external code or DSA has otherwise not finished analyzing all operations
  // on it, declare it type-unsafe.
  //
  if (node->isExternalNode() || node->isIncompleteNode())
    return false;

  //
  // If the pointer to the memory object came from some source not understood
  // by DSA or somehow came from/escapes to the realm of integers, declare it
  // type-unsafe.
  //
  if (node->isUnknownNode() || node->isIntToPtrNode() || node->isPtrToIntNode()) {
    return false;
  }

  return !((NodeInfo[node])[offset]); 
}

/// ResolveFunctionCall - Resolve the actual arguments of a call to function F
/// with the specified call site descriptor.  This function links the arguments
/// and the return value for the call site context-insensitively.
///
void
SteensgaardDataStructures::ResolveFunctionCall(const Function *F, 
                                                const DSCallSite &Call,
                                                DSNodeHandle &RetVal) {

  assert(ResultGraph != 0 && "Result graph not allocated!");
  DSGraph::ScalarMapTy &ValMap = ResultGraph->getScalarMap();

  // Handle the return value of the function...
  if (Call.getRetVal().getNode() && RetVal.getNode())
    RetVal.mergeWith(Call.getRetVal());

  // Loop over all pointer arguments, resolving them to their provided pointers
  unsigned PtrArgIdx = 0;
  for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
       AI != AE && PtrArgIdx < Call.getNumPtrArgs(); ++AI) {
    DSGraph::ScalarMapTy::iterator I = ValMap.find(AI);
    if (I != ValMap.end())    // If its a pointer argument...
      I->second.mergeWith(Call.getPtrArg(PtrArgIdx++));
  }
}

void DSMonitor::watch(DSNodeHandle N, std::vector<Value*> VS, std::string M) {
  if (N.isNull() || N.getNode()->isCollapsedNode()) {
    unwatch();
    return;
  }

  this->N = N;
  this->VS = VS;
  this->message = M;
  DSGraph *G = N.getNode()->getParentGraph();
  caption = getCaption(N.getNode(), G);

  if (!VS.empty()) {
    Instruction *I = getInstruction(VS[0]);
    if (I && I->getMetadata("dbg")) {
      const DebugLoc DL = I->getDebugLoc();
      auto *scope = cast<DIScope>(DL.getScope());
      location = scope->getFilename().str() + ":"
        + std::to_string(DL.getLine()) + ":"
        + std::to_string(DL.getCol());
    }
  }
}

// XXX duplicated from DSA/Printer.cpp XXX
static std::string getCaption(const DSNode *N, const DSGraph *G) {
  std::string empty;
  raw_string_ostream OS(empty);
  const Module *M = 0;

  if (!G) G = N->getParentGraph();

  // Get the module from ONE of the functions in the graph it is available.
  if (G && G->retnodes_begin() != G->retnodes_end())
    M = G->retnodes_begin()->first->getParent();
  if (M == 0 && G) {
    // If there is a global in the graph, we can use it to find the module.
    const DSScalarMap &SM = G->getScalarMap();
    if (SM.global_begin() != SM.global_end())
      M = (*SM.global_begin())->getParent();
  }

  if (N->isNodeCompletelyFolded())
    OS << "COLLAPSED";
  else {
    if (N->type_begin() != N->type_end())
      for (DSNode::TyMapTy::const_iterator ii = N->type_begin(),
           ee = N->type_end(); ii != ee; ++ii) {
        OS << ii->first << ": ";
        if (ii->second)
          for (svset<Type*>::const_iterator ni = ii->second->begin(),
               ne = ii->second->end(); ni != ne; ++ni) {
            Type * t = *ni;
            t->print (OS);
            OS << ", ";
          }
        else
          OS << "VOID";
        OS << " ";
      }
    else
      OS << "VOID";
    if (N->isArrayNode())
      OS << " array";
  }
  if (unsigned NodeType = N->getNodeFlags()) {
    OS << ": ";
    if (NodeType & DSNode::AllocaNode       ) OS << "S";
    if (NodeType & DSNode::HeapNode         ) OS << "H";
    if (NodeType & DSNode::GlobalNode       ) OS << "G";
    if (NodeType & DSNode::UnknownNode      ) OS << "U";
    if (NodeType & DSNode::IncompleteNode   ) OS << "I";
    if (NodeType & DSNode::ModifiedNode     ) OS << "M";
    if (NodeType & DSNode::ReadNode         ) OS << "R";
    if (NodeType & DSNode::ExternalNode     ) OS << "E";
    if (NodeType & DSNode::ExternFuncNode   ) OS << "X";
    if (NodeType & DSNode::IntToPtrNode     ) OS << "P";
    if (NodeType & DSNode::PtrToIntNode     ) OS << "2";
    if (NodeType & DSNode::VAStartNode      ) OS << "V";

#ifndef NDEBUG
    if (NodeType & DSNode::DeadNode       ) OS << "<dead>";
#endif
    OS << "\n";
  }

  //Indicate if this is a VANode for some function
  for (DSGraph::vanodes_iterator I = G->vanodes_begin(), E = G->vanodes_end();
      I != E; ++I) {
    DSNodeHandle VANode = I->second;
    if (N == VANode.getNode()) {
      OS << "(VANode for " << I->first->getName().str() << ")\n";
    }
  }

  EquivalenceClasses<const GlobalValue*> *GlobalECs = 0;
  if (G) GlobalECs = &G->getGlobalECs();

  for (DSNode::globals_iterator i = N->globals_begin(), e = N->globals_end();
       i != e; ++i) {
    (*i)->printAsOperand(OS,false,M);

    // Figure out how many globals are equivalent to this one.
    if (GlobalECs) {
      EquivalenceClasses<const GlobalValue*>::iterator I =
        GlobalECs->findValue(*i);
      if (I != GlobalECs->end()) {
        unsigned NumMembers =
          std::distance(GlobalECs->member_begin(I), GlobalECs->member_end());
        if (NumMembers != 1) OS << " + " << (NumMembers-1) << " EC";
      }
    }
    OS << "\n";
  }

  return OS.str();
}