Analyze function pointer by using data flow equation based on LLVM/Clang.
x=&y; S’ = S ⁄ {x →S(x)} ∪ {x →y}
x=y; S’ = S ⁄ {x →S(x)} ∪ {x →S(y)}
x=*y; S’ = S ⁄ {x →S(x)} ∪ {x →S(S(y))} OR S ⁄ {v →S(v)} ∪ {v →S(y)} (S(x)={v})
*x=y; S ∪ {v0 →S(y)} …∪ {vn →S(y)} (S(x)={v0…vn}) OR ⊤ (S(x)={})