LLVM, get the offset of inside struct

Question

I want to use fine-grained offset of each struct element in LLVM. For example:

struct A{
    int a;
    int b;
};
struct B{
    int c;
    struct A sa;
};
struct B s;

For struct B, I want to enumerate each element inside it, i.e: offset(s.c) = 0, offset(s.sa.a) = 4, offset(s.sa.b)=8. How can I get this information (which API could be used?) inside my pass other than dump()?

Answer 1

Use Module::getDataLayout to obtain a DataLayout object, which can give you a StructLayout as a return of DataLayout::getStructLayout. The StructLayout has getElementOffset() method, that does what you want.