[PERF] Optimize 3rd heaviest func, (81b -> 10m) #15043
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So this is funny, the query `tcx.module_children` was top 3 in most time consuming functions in Clippy, it was being called 24384 times in tokio. "Unacceptable!" I thought. Digging a bit around, turns out that `clippy::strlen_on_c_strings` was calling for `get_def_path` via `match_libc_symbol`. This query pretty-prints things and performs some analysis. Yes, we were running early lint checks to see if symbols were from `libc`. I don't really trust callgrind when it says I've turn 81 billion instructions into like 10 million. So I benchmarked this the good ol' "compiling 20 times without incr" method and it went from 0.31s-0.45s to 0.25s constistently. (Profiled, and "benchmarked") on tokio.
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…ange, r=compiler-errors Add a warning to LateContext::get_def_path Preventing anyone from doing the same error as rust-lang/rust-clippy#15043 fixed
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Rollup merge of #142593 - blyxyas:improve-docs-itty-bitty-change, r=compiler-errors Add a warning to LateContext::get_def_path Preventing anyone from doing the same error as rust-lang/rust-clippy#15043 fixed
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So this is funny, the query
tcx.module_childrenwas top 3 in mosttime consuming functions in Clippy, it was being called 24384 times in
tokio. "Unacceptable!" I thought. Digging a bit around, turns out that
clippy::strlen_on_c_stringswas calling forget_def_pathviamatch_libc_symbol. This query pretty-prints things and performs someanalysis.
Yes, we were running early lint checks to see if symbols were from
libc.I don't really trust callgrind when it says I've turn 81 billion instructions
into like 10 million. So I benchmarked this the good ol' "compiling 20 times
without incr" method and it went from 0.31s-0.45s to 0.25s constistently.
(Profiled, and "benchmarked") on tokio.
What I can get behind is via
strlen_on_c_stringschanging from 31 million instructions into 76k. 🎉 🥳changelog: [
strlen_on_c_strings]: Optimize it by 99.75%