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call graph(.dot) generated by clang libtooling has no node labels

I'm a beginner of clang libtooling. I'm trying to use clang::CallGraph viewGraph to generate a .dot file of my call graph. here is the code:

clang::CallGraph mCG;

for (unsigned i = 0 ; i < DeclsSize ; ++i) {
    clang::FunctionDecl *FnDecl = (clang::FunctionDecl *) (Decls[i]);
    mCG.addToCallGraph(FnDecl);
}

mCG.viewGraph();

The interesting thing is, the generated call graph file (.dot) has no node's labels, although I can print my call graph with all node's name correctly.

Here is the generated pic: enter image description here

I'm curious about why it shows like that. Which part is wrong in my code?

Thanks in advance!

Solution

  • I fixed this problem, but I'm not sure whether it is a correct way. Instead of invoking function - "viewGraph()", I use the "llvm::WriteGraph".

    Here is the code:

    string outputPath = "./";
outputPath.append("CallGraph");
outputPath.append(".dot");

// Write .dot
std::error_code EC;
raw_fd_ostream O(outputPath, EC, sys::fs::F_RW);

if (EC) {
    llvm::errs() << "Error: " << EC.message() << "\n";
    return;
}

llvm::WriteGraph(O, &mCG);

    Meanwhile, I changed the LLVM source code file -- GraphWriter.h

    void writeNode(NodeRef Node) {

std::string NodeAttributes = DTraits.getNodeAttributes(Node, G);

O << "\tNode" << static_cast<const void*>(Node) << " [shape=record,";
if (!NodeAttributes.empty()) O << NodeAttributes << ",";
O << "label=\"{";

if (!DTraits.renderGraphFromBottomUp()) {

  // I add here: for show the node's label value (otherwise the label will be empty)
  std::string nodeLable ;
  if(Node == G->getRoot()){
     nodeLable = "root";
  }
  else{
    const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(Node->getDecl());
    nodeLable = ND->getNameAsString();
  }

 // O << DOT::EscapeString(DTraits.getNodeLabel(Node, G));
  O << nodeLable;
...

    Anyway, it works for my code now. Not sure whether there are some other good ways.