feat: Add CMOV instruction to brillig and brillig gen

[sirasistant]

Resolves noir-lang/noir#4580

[fcarreiro]

LGTM but see my comment!

[fcarreiro]

Isn't the old code better? Now we unconditionally execute all of absolute value (in the AVM prover it would be some extra rows). I know it reads nicer, but probably the old code is better unless we care about branch prediction (which I think we don't :P)

[sirasistant]

Previously it was:

JUMPI then
JUMP else
CONST  // then
SUB
JUMP end
MOV // else
//end

Now it's

CONST
SUB
CMOV

So it's half the opcodes emitted
Regarding execution trace, previously, for the truthy case it was 4 opcodes, for the falsy case it was 3 opcodes. Now it's always 3 opcodes

I think now it's better! But it was mainly so CMOV was used and tested. The old case could probably have been optimized in a different way

[fcarreiro]

You are right!

[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 5f0f4fca 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	64 txs
l1_rollup_calldata_size_in_bytes	5,668	18,820	36,356
l1_rollup_calldata_gas	66,292	239,104	469,880
l1_rollup_execution_gas	647,390	929,462	1,306,060
l2_block_processing_time_in_ms	1,296 (-5%)	5,012 (+2%)	9,411 (-2%)
note_successful_decrypting_time_in_ms	192 (+13%)	521 (+1%)	1,045 (+1%)
note_trial_decrypting_time_in_ms	100 (+31%)	41.3 (+21%)	58.3 (-1%)
l2_block_building_time_in_ms	18,117 (-1%)	69,342 (-1%)	136,022
l2_block_rollup_simulation_time_in_ms	8,129 (-1%)	28,990 (-3%)	56,879
l2_block_public_tx_process_time_in_ms	9,967 (-1%)	40,299 (+1%)	79,045

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	14,142 (-2%)	26,434
note_history_successful_decrypting_time_in_ms	1,216 (+1%)	2,392 (-2%)
note_history_trial_decrypting_time_in_ms	64.9 (+3%)	116 (-30%)
node_database_size_in_bytes	18,657,360	35,061,840
pxe_database_size_in_bytes	29,859	59,414

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	274 (-3%)	44,366	28,244
private-kernel-ordering	210 (-2%)	52,868	14,326
base-parity	1,792 (-4%)	128	311
base-rollup	709 (-2%)	165,787	925
root-parity	1,618	1,244	311
root-rollup	51.2 (-1%)	4,487	725
private-kernel-inner	629 (-2%)	73,771	28,244
public-kernel-app-logic	436 (-2%)	35,260	28,215
public-kernel-tail	169 (-2%)	40,926	28,215
merge-rollup	8.36	2,696	925

Tree insertion stats

The duration to insert a fixed batch of leaves into each tree type.

Metric	1 leaves	16 leaves	64 leaves	128 leaves	512 leaves	1024 leaves	2048 leaves	4096 leaves	32 leaves
batch_insert_into_append_only_tree_16_depth_ms	9.85 (-2%)	15.8 (-2%)	N/A	N/A	N/A	N/A	N/A	N/A	N/A
batch_insert_into_append_only_tree_16_depth_hash_count	16.8	31.6	N/A	N/A	N/A	N/A	N/A	N/A	N/A
batch_insert_into_append_only_tree_16_depth_hash_ms	0.573 (-2%)	0.487 (-2%)	N/A	N/A	N/A	N/A	N/A	N/A	N/A
batch_insert_into_append_only_tree_32_depth_ms	N/A	N/A	45.4 (-1%)	71.7 (-1%)	231	433 (-3%)	873	1,731 (-1%)	N/A
batch_insert_into_append_only_tree_32_depth_hash_count	N/A	N/A	96.0	159	543	1,055	2,079	4,127	N/A
batch_insert_into_append_only_tree_32_depth_hash_ms	N/A	N/A	0.465 (-1%)	0.442 (-1%)	0.421	0.405 (-3%)	0.415	0.414	N/A
batch_insert_into_indexed_tree_20_depth_ms	N/A	N/A	53.0 (-1%)	105 (-2%)	336 (-1%)	641 (-4%)	1,313 (-1%)	2,612 (-1%)	N/A
batch_insert_into_indexed_tree_20_depth_hash_count	N/A	N/A	104	207	691	1,363	2,707	5,395	N/A
batch_insert_into_indexed_tree_20_depth_hash_ms	N/A	N/A	0.471 (-2%)	0.474 (-2%)	0.456	0.441 (-5%)	0.455 (-1%)	0.453 (-1%)	N/A
batch_insert_into_indexed_tree_40_depth_ms	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	60.9
batch_insert_into_indexed_tree_40_depth_hash_count	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	109
batch_insert_into_indexed_tree_40_depth_hash_ms	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	0.532 (-1%)

Miscellaneous

Transaction sizes based on how many contract classes are registered in the tx.

Metric	0 registered classes
tx_size_in_bytes	22,012

Transaction processing duration by data writes.

Metric	0 new note hashes	1 new note hashes
tx_pxe_processing_time_ms	3,140 (-3%)	1,716 (-2%)

Metric	0 public data writes	1 public data writes
tx_sequencer_processing_time_ms	13.7	1,216 (-2%)

[vezenovm]

Just noting this should be marked feat! as it is a breaking change.