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Comment by viktorcode | Hacker News Reader

After seeing Swift's result I had to look into the source to confirm that yes, it was not written by someone who knows the language.

But this is a good benchmark results that demonstrate what performance level can you expect from every language when someone not versed in it does the code porting. Fair play

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Author here. There are actually 3 Swift versions in the benchmark:

  - Swift (standard): 893ms
  - Swift (relaxed): 903ms (uses fast-math equivalent)
  - Swift (SIMD): 509ms (explicit SIMD4)

The standard version uses x *= -1.0 which creates a loop-carried dependency that blocks auto-vectorization - same issue as Crystal, Odin, Ada. The SIMD version uses the branchless i & 0x1 trick and is ~1.75x faster.

Fair point that someone versed in Swift would probably use the better pattern in the standard version too. PRs welcome to improve it! The goal was idiomatic-ish code, but I'm not an expert in all 40+ languages.

Even in verbose Java it's barely 20 lines.

Makes the benchmarks game 100 lines seem like major apps.

https://benchmarksgame-team.pages.debian.net/benchmarksgame/...

What do you think they could have done better in the Swift code?

Using overflow operators instead of the ones that check for that each iteration.

Reading https://github.com/niklas-heer/speed-comparison/blob/master/..., I think the only overflow checks could be in

  for i in 2...rounds+2

and I would hope/expect the compiler to be smart enough to know that it only has to check “rounds+2” once there. Swift isn’t exactly new anymore, and it’s supported by a large company.

What do I overlook?

There’s no way overflow checks are responsible for that enormous speed difference from C

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