Ah, I read the first link in the comments first, which really does imply they're using GP methods.
Ah, I read the first link in the comments first, which really does imply they're using GP methods.
Here's mine... (excuse my lack of formatting.)
The synthesis step of stochastic superoptimisation finds the next candidate program P’ by drawing an MCMC sample based on the previous candidate program P. It proposes P’ by randomly applying one of a few mutations to P:
* changing the opcode of a randomly selected instruction
* changing a random operand of a randomly selected instruction
* inserting a new random instruction
* swapping two randomly selected instructions
* deleting an existing randomly selected instruction
The MCMC sampler uses the cost function, which measures how “close” to the target program P’ is and how fast P’ is, to decide whether to accept the candidate P’. A candidate is more likely to be accepted if it is close to the target or very fast. But even programs that are slow or distant from the target have some probability of being accepted, ensuring we explore novel programs
What does "close" mean here? I don't see that explained.
If you're trying to match outputs, then this is just old-fashioned GP with a minor twist - i.e. including speed in the fitness function, which has the potential to find some novel local maxima, which produce outputs that are close to the target AND very fast.
If you're trying to match instruction sequences - then I don't see the point at all.
GP often fails because it runs out of steam before producing a definitively correct solution.
It's easy to design cost/fitness functions that get close but not close enough, and slightly harder to design functions that solve a non-trivial problem some of the time.
It's incredibly hard to design functions that find an answer reliably without getting lost in the problem space.
let candidate be some random program
while candidate not correct (per your SMT solver):
new_candidate = mutate candidate
let cost be cost of new_candidate
(varies by different techniques;
some just measure the number of bits differ
from expected output of testcases)
if cost is improved:
candidate = new_candidate
else, with some probability (the lower the cost, the higher the prob.):
candidate = new_candidate
It's just annoying that the implication is that the 'reinventors' haven't done their research. It's almost as bad as my original feeling of "that's an new old thing", and assuming malicious intent/plagiarism.