JIT: Set the IP and check for invalidation in `POP_TOP` only if `Py_Dealloc` is called.

The optimizer removes many POP_TOPs, but quite a few remain.

The code for POP_TOP looks like this:

    inst(POP_TOP, (value --)) {
        PyStackRef_XCLOSE(value);
    }

which is fine for the interprete but in the JIT, as POP_TOP is marked as escaping, we need to set the IP before and check for invalidation afterwards.

What we could do, is have a version of POP_TOP that sets the IP and checks for invalidation only if Py_Dealloc is called, so we don't need to add SET_IP and CHECK_VALIDITY.

The new form of POP_TOP would look like this:

    op(_POP_TOP_SET_IP_CHECK_INVALID, (value --)) {
        if (do_decref_and_refcnt_is_zero(value)) {
            SET_IP()
            Py_Dealloc()
            CHECK_VALID();
        }
   }

_POP_TOP_SET_IP_CHECK_INVALID should be inserted in the same pass that we insert _SET_IP and _CHECK_VALIDITY as we know whether we need to insert those uops, and leave POP_TOP alone in those cases.

Overall, this should speed things up as it doesn't increase the overall code size, but it does execute less code in many cases.

Inspecione a implementação JIT de POP_TOP e o pass que insere _SET_IP e _CHECK_VALIDITY. Rastreie do_decref_and_refcnt_is_zero e os caminhos existentes SET_IP, Py_Dealloc e CHECK_VALID; o trabalho estará concluído quando a forma especializada for inserida somente onde for necessária, enquanto POP_TOP permanecer inalterado em outros lugares e o comportamento de invalidação for preservado.