←back to thread

Zlib-rs is faster than C

(trifectatech.org)
341 points dochtman | 1 comments | 16 Mar 25 19:35 UTC | HN request time: 0.418s | source
Show context
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?

replies(30): >>43381895 #>>43381907 #>>43381922 #>>43381925 #>>43381928 #>>43381931 #>>43381934 #>>43381952 #>>43381971 #>>43381985 #>>43382004 #>>43382028 #>>43382110 #>>43382166 #>>43382503 #>>43382805 #>>43382836 #>>43383033 #>>43383096 #>>43383480 #>>43384867 #>>43385039 #>>43385521 #>>43385577 #>>43386151 #>>43386256 #>>43386389 #>>43387043 #>>43388529 #>>43392530 #
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!
replies(1): >>43382103 #
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.
replies(3): >>43382249 #>>43382631 #>>43386771 #
1. rcxdude ◴[17 Mar 25 10:07 UTC] No.43386771[source]▶
C's safe subset is so small as to be basically useless, and especially it's impossible to encapsulate behavior into a safe interface, in fact it's fairly easy in C to make an interface which is impossible to use correctly (gets() and the like).