Generating Control Flow Graph for c++ code

I want to analyzes c++ programs. What I am trying to do is generating control flow graph, run tests, and mark all vertexes that are hit. I know that GCC gives ability to generate CFG from compiled code with -fdump-tree-cfg. But the generated file is hard to read and I have no idea how to parse the file. So I have to questions here.

1. How to parse the generated cfg file by GCC?
2. How to mark all vertexes that are hit by running tests?

I found many related questions and answers, but no one satisfies my questions. Any idea would be appreciated.

Thanks