Sorry, I found the answer. I forgot that the thunk is a call to the Prestub. That call pushes the "return address" onto the stack. The "return address" happens to be the MethodDesc pointer. Clever!
Thanks, Nam Nam Tran wrote: > > I'm trying to understand the details of how the Prestub and the > JIT backpatch work. > > On x86, the PrestubFrame looks like: > > +... stack-based args for real method > +12 return address > +8 m_Datum (MethodDesc*) > +4 m_Next > ESI--->+0 the frame vptr > +... negative space stuff > > I can see that the call to the Prestub from _CallDescWorkerInternal > (asm) pushes the return address, then the Prestub prolog pushes > m_Next and the frame vptr. > > But I can't see where the MethodDesc* is pushed into ESI+8. But then > PreStubWorker() can get the MethodDesc* from the PrestubMethodFrame > object (previous ESI) just fine. What am I missing here? > > Thanks, > Nam
