For AlphaChip, pre-training is just training. You train, and save the weights in between. This has always been supported by the Google's open-source repository. I've read Kahng's FAQ, and he fails to address this, which is unsurprising, because there's simply no excuse for cutting out pre-training for a learning-based method. In his setup, every time AlphaChip sees a new chip, he re-randomizes the weights and makes it learn from scratch. This is obviously a terrible move.
HPWL (half-perimeter wirelength) is an approximation of wirelength, which is only one component of the chip floorplanning objective function. It is relatively easy to crunch all the components together and optimize HPWL --- minimizing actual wirelength while avoiding congestion issues is much harder.
Simulated annealing is good at quickly converging on a bad solution to the problem, with relatively little compute. So what? We aren't compute-limited here. Chip design is a lengthy, expensive process where even a few-percent wirelength reduction can be worth millions of dollars. What matters is the end result, and ML has SA beat.
(As for conflict of interest, my understanding is Cadence has been funding Kahng's lab for years, and Markov's LinkedIn says he works for Synopsis. Meanwhile, Google has released a free, open-source tool.)
HPWL (half-perimeter wirelength) is an approximation of wirelength, which is only one component of the chip floorplanning objective function. It is relatively easy to crunch all the components together and optimize HPWL --- minimizing actual wirelength while avoiding congestion issues is much harder.
Simulated annealing is good at quickly converging on a bad solution to the problem, with relatively little compute. So what? We aren't compute-limited here. Chip design is a lengthy, expensive process where even a few-percent wirelength reduction can be worth millions of dollars. What matters is the end result, and ML has SA beat.
(As for conflict of interest, my understanding is Cadence has been funding Kahng's lab for years, and Markov's LinkedIn says he works for Synopsis. Meanwhile, Google has released a free, open-source tool.)