Reduce wasm code size

[tomaka]

A few things that can be done:

• Use opt-level = "s" in our Cargo.toml profile. This shrinks the size by around 10%. Unfortunately the full-node would then also use opt-level = "s". Cargo custom profiles would help.
• Take inspiration from https://github.com/paritytech/cargo-contract/blob/3967026fbff153ea3553a307bf6e45a6fdef781b/src/cmd/build.rs
  • Passing -Zbuild-std -Zbuild-std-features=panic_immediate_abort requires a nightly Rust compiler and the Wasi SDK installed, which is annoying.
  • Passing -C link-arg=-z -C link-arg=stack-size=65536 didn't result in a significant difference for me.
• Run twiggy on CI #1

[tomaka]

At the moment, data[13] occupies around 1MiB. It contains panic messages.

It is possible that -Zbuild-std-features=panic_immediate_abort removes it entirely. If not, we should find a way to do so.

[tomaka]

Cargo custom profiles are soon to be stable.

[tomaka]

cc #1729

[tomaka]

This can be reduced further (at the moment, from 5.0 Mib to 4.5 MiB) by using wasm-snip --snip-rust-panicking-code. However, doing so means that we will not see the panic message nor stack frames, which is probably undesirable.

[tomaka]

cc #1801

[tomaka]

I don't see how to further improve the size of the Wasm, except by removing all panic messages, which would be very hard to do and is questionable.

Additionally, we don't have any target for the size of the Wasm, except "as little as possible".

Therefore closing this issue.