title: Is there a C code analyzer which can show usage of global variables in functions?
body: <p>right now I have a big project with legacy C/C++ source codes. There are many global variables spread in different functions. In order to analyze the code, I need a tool which can take a look into these functions, check what local/global variables are used and modified in this function, and then better show theses interfaces graphically. </p>
  
  <p>Does anyone have experience with this kind of analysis and know accordingly the tool names? I've tried Understand from SciTools, but it cannot deliver this kind of report. </p>
  
  <p>Thanks!</p>