frontend design for precompiles

[kunxian-xia]

Previously, we use layered circuit built from gates like mul3 / mul2 / add / add_const as the abstraction / frontend to program keccak circuit. This abstraction (defined in a line of works on GKR) is not efficient as we expected.

In this issue, we want to extract out ideas in the prototype made by @dreamATD in https://github.com/scroll-tech/ceno/tree/new-gkr-keccak so as to allow us write other precompiles in a easy way.

[matthiasgoergens]

Please provide some context and elaborate what's supposed to be done for this issue.

[kunxian-xia]

Please provide some context and elaborate what's supposed to be done for this issue.

Added. ☝️