AddReadAttrs vs. TargetMachine?

Hi,

I want to invoke the AddReadAttrs pass with my software backend (derived from TargetMachine like CBackend).
CBackend uses addPassesToEmitWholeFile-method for invoking several passes. I tried to use the same method, but it failed on runtime.
Running llc with my backend produces (mac os x 10.5 and llvm 2.4):

dyld: lazy symbol binding failed: Symbol not found: __ZN4llvm22createAddReadAttrsPassEv
   Referenced from: /myproject/build/Release/lib/mybackend.dylib
   Expected in: flat namespace

dyld: Symbol not found: __ZN4llvm22createAddReadAttrsPassEv
   Referenced from: /myproject/build/Release/lib/mybackend.dylib
   Expected in: flat namespace

Is it even possible to invoke such a pass from a backend?
Or is it only possible to run opt -addreadattrs first with bitcode-file and then llc ?

Thanks,
Nico

In addition to my first mail here is the error message I get from a linux box:

llc: symbol lookup error: /myproject/build/Release/lib/mybackend.so: undefined symbol: _ZN4llvm22createAddReadAttrsPassEv

Any idea?

Thanks a lot,
Nico