Picking the best synthesis result before implementation

On Thu, 30 Jul 2015 20:23:12 -0700, James07 wrote:

> Out of curiosity, I wrote a script to explore with different options in
> the Vivado software (2014.4), especially on the synthesis options under
> SYNTH_DESIGN, like FSM_extraction, MAX_BRAM etc. The script stops after
> synthesis, just enough to get the timing estimate. I explore everything
> except the directive because it seems like you use the directive, you
> cannot manually set the options
> 
> My goal is to see if it will give me a better result before I move on to
> implementation. However, out of the 50 different results I see that a
> lot of the estimated worst slacks and timing scores are the same. About
> 40% of the results report the same values. I ran on 3 sample designs and
> it gave me the same thing.
> 
> So my question is, is there a way to differentiate what is a better
> synthesis result? What should I look at in the report?

It is possible that you are giving tools too simple test-cases. Try 
giving them something complicated - like big designs with VERY much 
interconnectivity that also need to be fast - and see how they fare then.