Add a new BF implementation in Swift and compile the matmul.swift

[ricvelozo]

I'm using the -Ounchecked compiler flag like some other languages. The -lto compiler flag is apparently experimental, and cause link errors, so I didn't include it.

[dumblob]

I'm using the -Ounchecked compiler flag like some other languages.

This comes up every now and then - shouldn't we rather stop disabling the checks in all languages? Sure, it's unfair that some languages don't support these checks (or they do, but it's not a standard practice to use them - e.g. C++), but that's part of the definition of the language which this benchmark tries to showcase.

We have different implementations of the same test in the same language but utilizing different libraries or approaches. So why not to have two variants - one with bounds checking and the other without?

[ricvelozo]

I'm using the -Ounchecked compiler flag like some other languages.

This comes up every now and then - shouldn't we rather stop disabling the checks in all languages? Sure, it's unfair that some languages don't support these checks (or they do, but it's not a standard practice to use them - e.g. C++), but that's part of the definition of the language which this benchmark tries to showcase.

We have different implementations of the same test in the same language but utilizing different libraries or approaches. So why not to have two variants - one with bounds checking and the other without?

This is being discussed in #290. Still, the Rust implementation, the third fastest, don't use this type of optimization (just use unsafe to deduplicate the bounds checking), and the Swift version is still slower, as well as the Nim version.