←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: 2.009s | 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 #
1. pcwalton ◴[16 Mar 25 20:21 UTC] No.43381934[source]▶
> 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?

rustc uses LLVM just as clang does, so to a first approximation they're the same. For any given LLVM IR you can mostly write equivalent Rust and C++ that causes the respective compiler to emit it (the switch fallthrough thing mentioned in the article is interesting though!) So if you're talking about what's possible (as opposed to what's idiomatic), the question of "which language is faster" isn't very interesting.