3 ms·

Thanks; just the kind of response I was hoping for! Is the problem an inability to express real world design constraints in a high level HDL?

• gchadwick 3y ago
  I think the inherent problem is abstraction just doesn't work in the same way as it does in software. Various things keep pulling you down to the circuit level so if you're too far above it you're going to have a hard time as you have to reason through all those abstractions you built to avoid thinking about it. Closing timing (getting your design to pass timing analysis at a desired frequency) is a great example. Physical details like how many gates are on some path between flops, how far apart those flops are and how big the gates are (bigger gate, bigger drive, faster transitions) and what else is connected to them (more fan out more capacitance to drive, slower transitions) matter and in standard synchronous design this is pervasive across everything you do. Abstract too far from those details and closing timing becomes a nightmare. Imagine you wrote some standard data structure in the language of your choice. Now imagine the more call sites you have for the methods that manipulate it the slower it goes everywhere every single time you call it. Imagine some tiny edge case buried deep in the logic calling it occasionally could massively slow down accesses every time from everywhere. How would that change the way you build abstractions?