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Zlib-rs is faster than C

(trifectatech.org)
341 points dochtman | 5 comments | 16 Mar 25 19:35 UTC | HN request time: 0s | source
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YZF ◴[16 Mar 25 20:12 UTC] No.43381858[source]▶
I found out I already know Rust:

        unsafe {
            let x_tmp0 = _mm_clmulepi64_si128(xmm_crc0, crc_fold, 0x10);
            xmm_crc0 = _mm_clmulepi64_si128(xmm_crc0, crc_fold, 0x01);
            xmm_crc1 = _mm_xor_si128(xmm_crc1, x_tmp0);
            xmm_crc1 = _mm_xor_si128(xmm_crc1, xmm_crc0);
Kidding aside, I thought the purpose of Rust was for safety but the keyword unsafe is sprinkled liberally throughout this library. At what point does it really stop mattering if this is C or Rust?

Presumably with inline assembly both languages can emit what is effectively the same machine code. Is the Rust compiler a better optimizing compiler than C compilers?

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akx ◴[16 Mar 25 20:20 UTC] No.43381928[source]▶
To quote the Rust book (https://doc.rust-lang.org/book/ch20-01-unsafe-rust.html):

  In addition, unsafe does not mean the code inside the
  block is necessarily dangerous or that it will definitely
  have memory safety problems: the intent is that as the
  programmer, you’ll ensure the code inside an unsafe block
  will access memory in a valid way.
Since you say you already know that much Rust, you can be that programmer!
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silisili ◴[16 Mar 25 20:42 UTC] No.43382103[source]▶
I feel like C programmers had the same idea, and well, we see how that works out in practice.
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sunshowers ◴[16 Mar 25 21:40 UTC] No.43382631[source]▶
No, C lacks encapsulation of unsafe code. This is very important. Encapsulation is the only way to scale local reasoning into global correctness.
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1. chillingeffect ◴[17 Mar 25 04:03 UTC] No.43385092[source]▶
Eh. Good C programmers know what's safe and what's not. Often comments call out sketchy stuff. Just because it's not a language keyword, doesnt mean it's not called out.

Bad C programmers though? Their stuff is more dangerous and they don't know when and don't call it out and should probably stick to Rust.

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2. sunshowers ◴[17 Mar 25 04:11 UTC] No.43385138[source]▶
No, it's been proven over and over that simply knowing invariants is not enough, in long-term projects built by large teams where team members change over time. Even the most experienced C developers are going to fail every so often. You need tooling that automates those invariants, and you need that tooling to fail closed.

I take a hard line on this stuff because we can either keep repeating the fundamental mistake of believing things like "willpower" to write correct code are real, or we can move on and adopt better tooling.

3. fasterthanlime ◴[17 Mar 25 04:59 UTC] No.43385346[source]▶
True! Only, Good C programmers don’t exist.
4. hyperbrainer ◴[17 Mar 25 06:31 UTC] No.43385693[source]▶
And where can I find this mythical "Good C programmer"?
5. 12_throw_away ◴[17 Mar 25 17:01 UTC] No.43390514[source]▶
Dunno why this is being downvoted, obviously no true Scotsman would ever use memory after freeing it.