Added an optimized popcount TDM generator to bsg_misc

[klundblad]

This is a python script that generates a popcount .v file. It attempts to do a more optimized adder tree using the Three Dimensional Method (TDM). The following PPA analysis compares the original bsg_popcount.v to the generated popcount_tdm.v for widths 8, 32, 64, 128, and 1024.

The full PPA spreadsheet can be found here: https://docs.google.com/spreadsheets/d/1FjDbuVNZ45XHxjTXhP-kz8AH1CuP96d7sxJkHXT-KGA/edit?usp=sharing

[dpetrisko]

Hi can you commit the .v as well?

[taylor-bsg]

Let's try to get to the bottom of why we are not winning on frequency, especially for popcount <= 32.

[taylor-bsg]

You can compare the two netlists and also the STA reports.