feat: Standalone calldata test

[ledwards2225]

Adds a basic gate construction method for a calldata lookup and a standalone test to leave the DataBus PoC work in a slightly better state while I'm distracted with other things.

[AztecBot]

Benchmark results

No metrics with a significant change found.

Detailed results

All benchmarks are run on txs on the Benchmarking contract on the repository. Each tx consists of a batch call to create_note and increment_balance, which guarantees that each tx has a private call, a nested private call, a public call, and a nested public call, as well as an emitted private note, an unencrypted log, and public storage read and write.

This benchmark source data is available in JSON format on S3 here.

Values are compared against data from master at commit 217de090 and shown if the difference exceeds 1%.

L2 block published to L1

Each column represents the number of txs on an L2 block published to L1.

Metric	8 txs	32 txs	128 txs
l1_rollup_calldata_size_in_bytes	45,444	179,588	716,132
l1_rollup_calldata_gas	222,996	868,376	3,449,708
l1_rollup_execution_gas	867,105	3,746,429	23,306,473
l2_block_processing_time_in_ms	1,319	5,081	21,079
note_successful_decrypting_time_in_ms	353 (-6%)	1,113	4,138
note_trial_decrypting_time_in_ms	65.4 (-24%)	37.0 (-4%)	142 (+1%)
l2_block_building_time_in_ms	14,875	59,413	237,954
l2_block_rollup_simulation_time_in_ms	10,578	42,359	169,935
l2_block_public_tx_process_time_in_ms	4,266	16,979	67,752

L2 chain processing

Each column represents the number of blocks on the L2 chain where each block has 16 txs.

Metric	5 blocks	10 blocks
node_history_sync_time_in_ms	15,511 (+1%)	29,473 (+1%)
note_history_successful_decrypting_time_in_ms	2,822 (-4%)	5,602 (+1%)
note_history_trial_decrypting_time_in_ms	126 (+34%)	195 (+31%)
node_database_size_in_bytes	3,620,184	3,723,654
pxe_database_size_in_bytes	29,923	59,478

Circuits stats

Stats on running time and I/O sizes collected for every circuit run across all benchmarks.

Circuit	circuit_simulation_time_in_ms	circuit_input_size_in_bytes	circuit_output_size_in_bytes
private-kernel-init	211	44,709	25,561
private-kernel-ordering	137	30,953	14,809
base-rollup	1,080	128,374	881
root-rollup	82.7	4,088	889
private-kernel-inner	288	71,236	25,561
public-kernel-private-input	203	31,891	25,561
public-kernel-non-first-iteration	201	31,933	25,561
merge-rollup	9.82 (+1%)	2,608	881

Miscellaneous

Transaction sizes based on how many contracts are deployed in the tx.

Metric	0 deployed contracts	1 deployed contracts
tx_size_in_bytes	15,487	31,877

[Rumata888]

If I understand correctly, the way it's implemented there is no connection with other parts of the circuit, so effectively we're saying "We're reading something". A malicious prover can read from any slot then

[ledwards2225]

Yeah it's a fair point. I'm kind of being lazy here and leaving things in an incomplete state. Are you suggesting that the index should instead be an index into the variables array?

[Rumata888]

Could you please change the read_calldata_at_index function to accept a variable index instead of a databus position index

[Rumata888]

I think the way it is right now, the verification key would change depending on read_index_values. If someone were to take this test and use databus based on this pattern it could be dangerous. Ideally we'd create a new variable with the same value here.

[ledwards2225]

updated so that the witness used in the lookup is unique as we discussed offline

[Rumata888]

The gate should work, but I feel that the test might be confusing to someone who hasn't looked into the arithmetization

[Rumata888]

LGTM