feat(experiment): Compare bincode against other serialisation formats

[aakoshh]

Description

Problem*

Related to #7511

Summary*

Comparing the impact on bytecode size of switching to a different serialisation format.

Additional Context

I'm interested in figuring out whether we can use one of the schema-less formats without paying too high a price for a backwards compatible format in terms of bloated bytecode size.

Compiling contracts

Run these commands to compile noir protocol circuits and contracts in aztec-packages after rebuilding nargo:

cargo build -p nargo_cli --release
./target/release/nargo --program-dir ../aztec-packages/noir-projects/noir-protocol-circuits compile --force --silence-warnings --skip-underconstrained-check
./target/release/nargo --program-dir ../aztec-packages/noir-projects/noir-contracts compile --force --silence-warnings --skip-underconstrained-check

Baseline

Recorded the bytecode size with bincode before switching to other implementations:

./scripts/bytecode-sizes/print-bytecode-size.sh ../aztec-packages > ./scripts/bytecode-sizes/bincode.jsonl

Comparing bytecode

Run these commands to record a new measurement (e.g. flexbuffers here) and compare against bincode.

./scripts/bytecode-sizes/print-bytecode-size.sh ../aztec-packages > ./scripts/bytecode-sizes/flexbuffers.jsonl
./scripts/bytecode-sizes/compare-bytecode-size.sh ./scripts/bytecode-sizes/bincode.jsonl ./scripts/bytecode-sizes/flexbuffers.jsonl > ./scripts/bytecode-sizes/bincode-vs-flexbuffers.jsonl
./scripts/bytecode-sizes/plot-bytecode-size.sh ./scripts/bytecode-sizes/bincode-vs-flexbuffers.jsonl

Documentation*

Check one:

• No documentation needed.
• Documentation included in this PR.
• [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Compilation Time'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.20.

Benchmark suite	Current: 67e98a9	Previous: 6f78848	Ratio
global_var_regression_entry_points	2.03 s	0.541 s	3.75

This comment was automatically generated by workflow using github-action-benchmark.

CC: @TomAFrench

[aakoshh]

CBOR shows a stable 5-10% overhead for circuits over 10KB in size; below that the overhead goes up to +170% percent.

[aakoshh]

FlexBuffers has a higher base overhead and doesn't show any trend of converging to a lower value for larger circuits, going from +200% to +700%:

[aakoshh]

This is the results of comparing bincode to protobuf: Protobuf is 10%-20% worse until 1KB, then 10%-20% better. Beats CBOR, as expected.