Dumping the Vtable

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1

Hi,

Can someone help me with how to dump the vtable and the vptr addresses within it?

Thanks,

Dami

2

Hi Damilola,

Can someone help me with how to dump the vtable and the vptr addresses
within it?

I'm not sure if this answers your question exactly, but you can pass
"-Xclang -fdump-vtable-layouts" to ask Clang to dump the layout of
generated vtables. For example:

$ cat /tmp/a.cc
struct S {
  virtual void f() {};
};

void f(S * s) {
  s->f();
}
$ bin/clang++ -c /tmp/a.cc -Xclang -fdump-vtable-layouts
Vtable for 'S' (3 entries).
   0 | offset_to_top (0)
   1 | S RTTI
       -- (S, 0) vtable address --
   2 | void S::f()

VTable indices for 'S' (1 entries).
   0 | void S::f()

- Hans

3

Hi Hans,

Thanks for the reply. I apologize for the unclear question. I am new to using clang and llvm.

I have tried this but the version I have for some reason won’t allow me to use this command line option. Furthermore, I am trying to get this information via the IR and writing a pass to get this information to use at a later point.

-Dami