It's been a year now since I first asked this question below, and I'm inquiring has anything been done on introducing a fill or clear method in Rust that can do a fast bulk zeroing (setting mem elements to '0') of arrays/slices? [image] Fastest way to zero an array help T…

Sure looks like a fill methods exists now. Edit: It seems to be slightly suboptimal for your use case in current stable rust, but that’s already fixed on nightly .

The codegen for .fill(0) is very different to .iter_mut().for_each(|m| *m = 0). Here is the .iter_mut().for_each(|m| *m = 0) assembly: test rsi, rsi je .LBB0_1 mov rdx, rsi xor esi, esi jmp qword ptr [rip + memset@GOTPCREL] .LBB0_1: …

[image] Kestrer: That will invoke this specialized implementation , which I'm guessing will just become a memset. It's a shame that isn't inlined though - there's one extra function call :(. Someone should probably make a PR that adds #[inline] to those specialized implementations .

Well, let’s see if someone picks this up https://github.com/rust-lang/rust/issues/83235

Thanks for the quick response to my question. I'm using Rust 1.50, and tried out fill in my code. I did a quick test with the original code for two inputs that took ~13 mins to run, to see accumulative affects between versions. In one case using fill was about 6 secs slower, while the other case w…

You can add the nightly toolchain rustup install nightly and then you can use it manually by adding the +nightly argument to cargo (or other rust-related commands). Eg cargo +nightly build or cargo +nightly run, etc, will use the nightly toolchain. You can also set your default toolchain to nightly…

Thanks again. :slightly_smiling_face:

Fastest way to zero an array, followup

help

jzakiya March 17, 2021, 6:34pm 8

Thanks again.

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Fastest way to zero an array, followup

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