Bit reversal on twiddle factors on inverse FFT
The answer to your question can be found just in reading the comments in the C code that you quoted. The process looks like this:


The input vector x is passed through a function DSPF_sp_cfftr2_dit(), which is described as a radix-2 decimation-in-time forward FFT. It expects its input in normal order and writes its output in bit-reversed order. It expects its twiddle factors to be in bit-reversed order (which they are, as shown in the first two lines of the function).
The forward FFT result is passed through another function DSPF_sp_icfftr2_dif(), which is described as a radix-2 decimation-in-frequency inverse FFT. It expects its input in bit-reversed order (which it is, as the input is the output of the forward FFT above, which was in bit-reversed order). It expects its twiddle factors to be in bit-reversed order (which they are). It writes its output in normal order.


So, what you have is an input vector x that starts in normal order and runs through an FFT/IFFT round trip, resulting in a vector that is also in normal order (and should be approximately identical to the original vector x).