* Automatically select FRI reduction arities
This way when a proof's degree changes, we won't need to manually update the `FriConfig`s of any recursive proofs on top of it.
For now I've added two methods of selecting arities. The first, `ConstantArityBits`, just applies a fixed reduciton arity until the degree has shrunk below a certain threshold. The second, `MinSize`, searches for the sequence of arities that minimizes proof size.
Note that this optimization is approximate -- e.g. it doesn't account for the effect of compression, and doesn't count some minor contributions to proof size, like the Merkle roots from the commit phase. It also assumes we're not using Merkle caps in serialized proofs, and that we're inferring one of the evaluations, even though we haven't made those changes yet.
I think we should generally use `ConstantArityBits` for proofs that we will recurse on, since using a single arity tends to be more recursion-friendly. We could use `MinSize` for generating final bridge proofs, since we won't do further recursion on top of those.
* Fix tests
* Feedback
* Replace `CrandallQuarticField` with a more generic `QuarticExtension`
And likewise for `CrandallQuadraticField`.
There are a few parameters which we can't automatically derive (in const Rust), so I specified them in a `AutoExtendable` trait.
This would make it fairly easy to add extension fields for `GoldilocksField` and any future fields.
* Attempt to derive 2-adicity, see Hamish's feedback
* Simplify TWO_ADICITY based on chat with Hamish
* PR feedback
* Merge AutoExtendable into Extendable (#235)
* Refactor GMiMC code
Adds a sub-trait of `Field` called `GMiMCInterface`, which is similar to `PoseidonInterface`.
This lets us have different fields with different GMiMC constants in a type-safe way.
* Remove `Interface`
* Const generic for width
* Move some Field members to a Field64 subtrait
I.e. move anything specific to 64-bit fields.
Also, relatedly,
- Tweak a bunch of prover code to require `Field64`, since 64-bit stuff is used in a couple places, like the FRI proof-of-work
- Remove `bits()`, which was unused and assumed a 64-bit field
- Rename a couple methods to reflect that they're u64 variants
There are no functional changes.
* Field64 -> PrimeField
* Remove `exp_u32`, `kth_root_u32`
* PrimeField: PrimeField
* Move `to_canonical_biguint` as well
* Add back from_noncanonical_u128
- Made some methods public, if they seemed like they'd be useful crates that depend on plonky2, and seemed like good/stable APIs
- Deleted a few things I didn't think seemed very useful
- Left a few for now that I was on the fence about
* Start work on optimized transpose
* Optimized transpose: 12-14% improvement on benchmark
* Transpose: Avoid bounds checks and change order of loops dynamically
* Transpose: re-enable bounds checks
* Disable ZK in large_config
Speeds up the tests from ~6m to ~1m (debug mode). `large_config` is crate-private so I don't think we need to worry about real users forgetting ZK, and I don't think ZK seems important in these tests, though we should probably have ZK enabled for a couple tests.
A couple tests need ZK or they fail; I added a TODO to look later.
This led to a few other changes:
- Fixed a bug where `trim` could truncate the final poly to a non-power-of-two length. This was improbable when ZK is on due to randomization.
- Gave a few methods access to the whole `CircuitConfig` vs `FriConfig` -- sort of necessary for the above fix, and I don't think there's much downside.
- Remove `cap_height` from `FriConfig` -- didn't really need it any more after giving more methods access to `CircuitConfig`, and having a single copy of the param feels cleaner/safer to me.
* PR feedback
* Add a reduce_polys_base
Reducing the polynomials in `open_plonk` was taking ~100ms on my machine. It was converting BF polynomials to the EF early on; by doing more work in the BF we can reduce it to ~20ms.
* PR feedback
