Time bounding opt/abc optimization

[j2kun]

Hi there!

I am somewhat novice in Yosys/ABC, and the circuit I'm optimizing takes ~2h to finish when running abc -lut 3, and I'm wondering if there's a mechanism by which I can specify that ABC should optimize as much as it can in, say, 10 minutes and then stop.

Similarly, I'm wondering if there is a way to time-bound opt, in that it could loop as long as it likes, and stop after 10 minutes or the design stops changing, whichever comes first.

[nakengelhardt]

We don't have any time-based limits because it would lead to non-deterministic outcomes, which is undesirable in many cases. abc and opt have -fast options, but if you don't want to use these universally, I'm afraid you'd have to go mess with the code. For opt it shouldn't be too hard to add a condition in the while loop, but for abc since that runs in an external program you'd have to see if there's any way to get the (famously inscrutable) abc code to do what you want...