Use sort_by_cached_key where appropriate #49525
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src/librustc_resolve/lib.rs
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| @@ -3577,7 +3576,7 @@ impl<'a> Resolver<'a> { | |||
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| let name = path[path.len() - 1].node.name; | |||
| // Make sure error reporting is deterministic. | |||
| names.sort_by_key(|name| name.as_str()); | |||
| names.sort_by_cached_key(|name| name.as_str()); | |||
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.as_str() is typically -> &str and thus cheap, so maybe double-check this one.
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This method is coming from:
rust/src/libsyntax_pos/symbol.rs
Lines 113 to 119 in e38eca6
which seemed non-trivial (but perhaps it can be optimised quite effectively?).
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Hmm, it's probably fairly cheap, but might be worth caching it anyway so the sort code is easier for the compiler to deal with. Thanks for resolving the type :)
src/librustc_trans/base.rs
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| @@ -825,7 +825,7 @@ pub fn trans_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, | |||
| // a bit more efficiently. | |||
| let codegen_units = { | |||
| let mut codegen_units = codegen_units; | |||
| codegen_units.sort_by_key(|cgu| usize::MAX - cgu.size_estimate()); | |||
| codegen_units.sort_by_cached_key(|cgu| usize::MAX - cgu.size_estimate()); | |||
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This sure looks like it wants |cgu| cmp::Reverse(cgu::size_estimate()), though I don't know if that's this PR
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Oh, that's a good point; I may as well fix that one here in passing.
| @@ -799,7 +799,7 @@ impl<'a, 'gcx, 'tcx> ProbeContext<'a, 'gcx, 'tcx> { | |||
| .collect(); | |||
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| // sort them by the name so we have a stable result | |||
| names.sort_by_key(|n| n.as_str()); | |||
| names.sort_by_cached_key(|n| n.as_str()); | |||
scottmcm
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Mar 31, 2018
| @@ -1435,9 +1435,7 @@ impl<'a, 'tcx, 'rcx> AutoTraitFinder<'a, 'tcx, 'rcx> { | |||
| // involved (impls rarely have more than a few bounds) means that it | |||
| // shouldn't matter in practice. | |||
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Also probably not this PR, but this comment makes me wonder if it would be worth adding if len < 2 { return } to the checks excerpted below, since sort_by_cached_key is currently a pessimization in the len==1 case, as it'll compute the key and allocate, which ordinary sort_by_key wouldn't.
Lines 1402 to 1406 in 1c5283b
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That's another good point: I'll add that extra check in! (len == 2 could also be special cased to not allocate, as only one comparison will be executed, but that's a less likely case to encounter.)
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Can you also use rust/src/librustc_mir/monomorphize/partitioning.rs Lines 192 to 196 in 9ceaa56 This could just be let mut items: Vec<_> = self.items().iter().map(|(&i, &l)| (i, l)).collect();
items.sort_by_cached_key(|&(i, _)| item_sort_key(tcx, i));
items |
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@sinkuu: Good catch, thanks! |
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☔ The latest upstream changes (presumably #49661) made this pull request unmergeable. Please resolve the merge conflicts. |
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| } | ||
| }); | ||
| // The sort doesn't case-fold but it's doubtful we care. | ||
| lints.sort_by_cached_key(|x: &&Lint| (x.default_level(sess), x.name)); |
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@bors r=scottmcm |
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📌 Commit e7aa139 has been approved by |
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…n, r=scottmcm Use sort_by_cached_key where appropriate A follow-up to rust-lang#48639, converting various slice sorting calls to `sort_by_cached_key` when the key functions are more expensive.
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Rollup of 14 pull requests Successful merges: - #49525 (Use sort_by_cached_key where appropriate) - #49575 (Stabilize `Option::filter`.) - #49614 (in which the non-shorthand patterns lint keeps its own counsel in macros) - #49665 (Small nits to make couple of tests pass on mips targets.) - #49781 (add regression test for #16223 (NLL): use of collaterally moved value) - #49795 (Properly look for uninhabitedness of variants in niche-filling check) - #49809 (Stop emitting color codes on TERM=dumb) - #49856 (Do not uppercase-lint #[no_mangle] statics) - #49863 (fixed typo) - #49857 (Fix "fp" target feature for AArch64) - #49849 (Add --enable-debug flag to musl CI build script) - #49734 (proc_macro: Generalize `FromIterator` impl) - #49730 (Fix ICE with impl Trait) - #48270 (Replace `structurally_resolved_type` in casts check.) Failed merges:
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A follow-up to #48639, converting various slice sorting calls to
sort_by_cached_keywhen the key functions are more expensive.