We change `CellValue` into a typedef of `AssignedCell` to simplify the
migration in this commit.
The migration from `CellValue` to `AssignedCell` requires several other
changes:
- `<CellValue as Var>::value()` returned `Option<F>`, whereas
`AssignedCell::<F, F>::value()` returns `Option<&F>`. This means we
need to dereference, use `Option::cloned`, or alter functions to take
`&F` arguments.
- `StateWord` in the Poseidon chip has been changed to a newtype around
`AssignedCell` (the chip was written before `CellValue` existed).
Previously, fixed_y_q was a non-binary selector that both loaded
the y_Q value and toggled the y_Q gate.
Now, the gate is toggled by a q_s4 simple selector, while the value
is loaded into a separate fixed column.
The Sinsemilla chip witnesses message pieces in individual regions, and
then copies them into the `hash_piece` region to initialize the running
sum. Previously these occured in the same column, but we can reduce the
utilized rows of the Action circuit by moving these into a less-used
column.
If https://github.com/zcash/halo2/issues/334 is implemented, this change
would be unnecessary, as the witnessed message piece regions would never
be assigned into the circuit.
We were configuring multiple instances of this across all of the advice
columns, in order to spread their assignments. However, we are actually
more constrained by columns than rows, and we have comparatively few
rows of range check logic required for the Action circuit.
We now use a single LookupRangeCheckConfig for the entire circuit. The
reduction in lookup arguments and fixed columns cuts the proof size in
half (now at 6048 bytes when using `floor_planner::V1`).
Co-authored-by: therealyingtong <yingtong@z.cash>
The Action Circuit configuration uses 10 advice columns. It contains:
- a single EccConfig (10 advice columns);
- two SinsemillaConfigs (5 advice columns each);
- two MerkleConfigs (5 advice columns each);
- a PoseidonConfig, (4 advice columns);
- a PLONKConfig for standard PLONK operations (3 advice columns);
and some infrastructure to handle public inputs (subject to change
at the time of commit).
The 5-column configs are placed side-by-side in the circuit to
optimize space usage.
Gate creation is delegated to the configure() function of each
respective Chip.
- `halo2::plonk::{create_proof, verify_proof}` now take instance columns
as slices of values.
- `halo2::plonk::Permutation` has been replaced by a global permutation,
to which columns can be added with `ConstraintSystem::enable_equality`.
- The introduction of blinding rows means that various tests now require
larger circuit parameters.
This has three const generic parameters: PATH_LENGTH, K, MAX_WORDS.
PATH_LENGTH is the length of the Merkle path being hashed. K and
MAX_WORDS parameterize the internal Sinsemilla instance used in
hashing the path.
therealyingtong
Jack Grigg
Daira Hopwood