1，建立感性认识

1.1 源码

hello.c

int x = 10;
int y = 11;
int main(){
    int z = 12;
    for (int i = 0;i < 10;i++){
        z *= x * y;
    }


        if(z>7.0)
                z=1.0f;
        else
                z = 2.0f;

        return 0;
}

1.2 编译

 2005  sudo apt-get install -y graphviz-doc libgraphviz-dev graphviz

 2034  ../ex_llvm/local_dbg/bin/clang -S -emit-llvm hello.c -o hello.ll
 2035  ls
 2036  ../ex_llvm/local_dbg/bin/opt --dot-callgraph hello.ll
 2037  ls
 2038  dot callgraph.dot -Tpng -o cfg.png
 2039  ls
 2040  pwd
 2041  ../ex_llvm/local_dbg/bin/opt --dot-cfg hello.ll
 2042  ls
 2043  dot cfg.main.dot -Tpng -o cfg.main.dot.png
 2044  history

 

1.3 效果图

2.控制流图分析原理

未完待续。。。