Identifying user define function through llvm pass

Question

Is there anyway by which I can identify whether the callee function is a user define or not? For example:

void foo()
{
   printf("hello world again");
}
int main()
{
   printf("hello world\n");
   foo();
}

As in this case foo() is a user define, whereas printf() is a library function.

The method I'm currently using is to iterate over all the modules and check if its size is greater than 0 or not. i.e:

for(Module::iterator F = M.begin(); F != M.end(); ++F)
{
    Function &Func = *F;
    if(F->size()>0)
        errs() << "User Define";
}

But am not sure about its accuracy?

score 8 · Accepted Answer · answered May 29 '14 at 14:01

8

You can use the isDeclaration method to check whether the function is defined or just declared in the module. This will let you differentiate between functions whose implementation is in the module and function that are expected to be found outside it.

answered May 29 '14 at 14:01

Eli Bendersky

263,248
89
350
412

What about the method that I've used (as shown above in question)? – Abhinash Jain May 29 '14 at 20:53
1

@AbhinashJain: I think the two amount to the same thing (under the hood `GlobalValue::isDeclaration` checks for emptiness for functions. However, `isDeclaration` seems preferable to me because its intention is clearer, and it works for other kinds of globals, like variables. – Eli Bendersky May 30 '14 at 02:10

Identifying user define function through llvm pass

1 Answers1