Open asomers opened 5 years ago
Thanks for the report. Which OS are you using, and are the cargo-kcov version between 09-06 and 10-01 the same?
I'm using FreeBSD 11.2 amd64. I haven't checked any nightly compilers between 09-06 and 10-01.
Thanks.
I haven't checked any compiles between 09-06 and 10-01
I mean the version of cargo-kcov
itself, not the compiler 😅
Oh, sorry. I'm using cargo-kcov 0.5.0.
Same results with cargo-kcov 0.5.2.
I bisected the compiler version. The slowdown was introduced in rustc 1.30.0-nightly (2ab3eba30 2018-09-14). It was not present in rustc 1.30.0-nightly (90d36fb59 2018-09-13).
Thanks. The range https://github.com/rust-lang/rust/compare/90d36fb59...2ab3eba30 contains quite many PRs, but I think it's caused by cargo-kcov not updated to properly handle rust-lang/rust#53829.
Wow! Cool that you found it so quickly. I'm going to leave it to you then, unless you need any more help from me.
Hm, it looks like upstream may have fixed things already. The problem is gone with the latest compiler. In fact, it's faster than ever before. Version rustc 1.31.0-nightly (de9666f12 2018-10-31) takes 6.08s.
Running
cargo kcov
is much slower with recent compilers. For example, asomers/futures-locks takes:nightly-2018-09-06-x86_64: 18.38s nightly-2018-10-01-x86_64: 61.46s nightly-2018-10-15-x86_64: 61.14s 1.30.0 (da5f414c2 2018-10-24): 60.08s
I don't know if this is a problem with rustc or cargo-kcov, but I haven't noticed any problems except when using kcov.