Performance dropping low when pushing arrays to BoundedVec

[Pasifaee]

Aim

Getting this code to compile considerably fast:

global COUNT = 400;

fn main() -> pub BoundedVec<[Field; 1], COUNT> {
    let mut result = BoundedVec::new();
    let mut x = 0;

    for _ in 0..COUNT {
        if (x < 1) {
            result.push([0]);
        }
    }

    result
}

Expected Behavior

The code compiles fast.

Bug

The code takes 30 seconds to compile on my machine.

To Reproduce

1. Compile the code

Project Impact

Nice-to-have

Impact Context

No response

Workaround

Yes

Workaround Description

No response

Additional Context

No response

Installation Method

None

Nargo Version

nargo version = 0.28.0 noirc version = 0.28.0+7dfa151da95c7ca9e1aaa752347b62f9fafe2c2c

NoirJS Version

No response

Would you like to submit a PR for this Issue?

None

Support Needs

No response

[jfecher]

This runs in under half a second running with nargo e on master. Likewise for proving and verifying.

[jfecher]

I've confirmed this takes about 24s for me on commit 7dfa151, so it has been fixed on master since then.

After a git bisect I determined #4716 is the culprit for optimizing this. Although everything was known at compile-time, that PR reduced the number of instructions to merge the arrays in this case from N = 400 each iteration to just the 1 differing element.

Closing this issue - you should see this change once #4716 is included in a release.