Wrap some query results in Lrc.
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r? @varkor (rust_highfive has picked a reviewer for you, use r? to override) |
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| } else { | ||
| tcx.predicates_of(def_id).predicates | ||
| tcx.predicates_of(def_id).predicates.clone() |
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Unnecessary clone, can just keep the whole Lrc in the predicates variable and change the loop below.
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I tried and failed to do that. I can't use the Rc directly, because that would move it. I can't use a reference, because it doesn't live long enough.
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Ok, I worked out a different way to do it.
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I don't see any reason this can't work:
let predicates = if def_id.is_local() {
tcx.explicit_predicates_of(def_id)
} else {
tcx.predicates_of(def_id)
};Then you do predicates.predicates.iter() below instead of predicates.into_iter().
eddyb
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Nov 8, 2018
src/librustc_typeck/collect.rs
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| @@ -1794,7 +1795,7 @@ fn explicit_predicates_of<'a, 'tcx>( | |||
| // on a trait we need to add in the supertrait bounds and bounds found on | |||
| // associated types. | |||
| if let Some((_trait_ref, _)) = is_trait { | |||
| predicates.extend(tcx.super_predicates_of(def_id).predicates); | |||
| predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().map(|p| *p)); | |||
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I think the .map(|p| *p) here and elsewhere could be replaced by .cloned().
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Won't that cause additional refcounting that the .map(|p| *p) won't?
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No, it does .map(|p| p.clone()) which is the same as .map(|p| *p) when the latter works because the latter only works when typeof(*p): Copy and Copy implies Clone is just a copy.
eddyb
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Nov 8, 2018
| @@ -1112,8 +1112,8 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx>+'o { | |||
| { | |||
| let tcx = self.tcx(); | |||
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| let bounds = self.get_type_parameter_bounds(span, ty_param_def_id) | |||
| .predicates.into_iter().filter_map(|(p, _)| p.to_opt_poly_trait_ref()); | |||
| let predicates = &self.get_type_parameter_bounds(span, ty_param_def_id).predicates; | |||
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Hah, it's cool that this works! (I think it's a case of the generalization of let x = &f();)
eddyb
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Nov 8, 2018
src/librustc/ty/mod.rs
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| let predicates = tcx.predicates_of(self.did).predicates; | ||
| if predicates.into_iter().any(|(p, _)| p == sized_predicate) { | ||
| let predicates = &tcx.predicates_of(self.did).predicates; | ||
| if predicates.into_iter().any(|(p, _)| *p == sized_predicate) { |
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You changed into_iter to iter elsewhere, can you do it here too?
eddyb
reviewed
Nov 8, 2018
| @@ -127,7 +127,7 @@ define_queries! { <'tcx> | |||
| /// predicate gets in the way of some checks, which are intended | |||
| /// to operate over only the actual where-clauses written by the | |||
| /// user.) | |||
| [] fn predicates_of: PredicatesOfItem(DefId) -> ty::GenericPredicates<'tcx>, | |||
| [] fn predicates_of: PredicatesOfItem(DefId) -> Lrc<ty::GenericPredicates<'tcx>>, | |||
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Please also change predicates_defined_on and type_param_predicates.
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@eddyb: I've updated, addressing the comments, and converting the remaining |
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eddyb
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Nov 9, 2018
| parent: None, | ||
| predicates: vec![], | ||
| }, | ||
| }), | ||
| |parent| { | ||
| let icx = ItemCtxt::new(tcx, parent); | ||
| icx.get_type_parameter_bounds(DUMMY_SP, def_id) |
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If you clone the GenericPredicates here you don't need an extra variable.
nikomatsakis
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Nov 12, 2018
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Seems fine, but maybe we could make it read a bit nicer? I've found that this use-case is very well handled by the make_mut family of functions; it might even be worth adding an extend or something that first invokes make_mut, so that we can just do predicates.extend(...) and make it just work. (Key thing would be to avoid doing anything if there are no items to extend with)
Thoughts?
src/librustc_typeck/collect.rs
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| icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))); | ||
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| let mut preds = result.predicates.clone(); | ||
| preds.extend(extra_preds); |
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should we maybe check if extra_preds.is_empty and avoid the clone?
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I can't quite tell what the type of result is here though
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The correct solution is make_mut, IMO, as discussed on IRC.
src/librustc_typeck/collect.rs
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| let explicit = tcx.explicit_predicates_of(def_id); | ||
| let span = tcx.def_span(def_id); | ||
| let predicates = explicit.predicates.into_iter().chain( | ||
| let predicates = explicit.predicates.iter().cloned().chain( |
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A lot of time, inferred_outlives_of will be empty -- maybe we should check for that?
If we added Lrc::make_mut, we could do:
let mut predicates = tcx.explicit_predicates_of(def_id);
let inferred_outlives = tcx.inferred_outlives_of(def_id);
if !inferred_outlives.is_empty() {
let predicates = Lrc::make_mut(&mut predicates);
predicates.predicates.extend(inferred_outlives.iter().map(|&p| (p, span)));
}or something like that
src/librustc_typeck/collect.rs
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| let span = tcx.def_span(def_id); | ||
| predicates.push((ty::TraitRef::identity(tcx, def_id).to_predicate(), span)); | ||
| } | ||
| preds.push((ty::TraitRef::identity(tcx, def_id).to_predicate(), span)); |
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Similarly here we could do this more elegant with make_mut I think
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I have updated the code to use r? @eddyb |
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@bors try |
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⌛ Trying commit 7b25382ed1210a942d06b01d6861853d874c2fda with merge 0efff4d7654f6a01ae707446fe13f85adaf93b0e... |
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☀️ Test successful - status-travis |
eddyb
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Updated to address the most recent comment. |
eddyb
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Nov 13, 2018
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☔ The latest upstream changes (presumably #55649) made this pull request unmergeable. Please resolve the merge conflicts. |
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I rebased and reinstated the @bors r=eddyb |
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📌 Commit 5ddf50d18b30b3a3fe2a308be3d74c596ed5adf6 has been approved by |
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So that the frequent clones in `try_get` are cheaper. Fixes rust-lang#54274.
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Oh, that @bors r=eddyb |
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📌 Commit 98dab33 has been approved by |
pietroalbini
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Nov 15, 2018
Wrap some query results in `Lrc`. So that the frequent clones in `try_get` are cheaper.
bors
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Nov 15, 2018
Rollup of 17 pull requests Successful merges: - #55182 (Redox: Update to new changes) - #55211 (Add BufWriter::buffer method) - #55507 (Add link to std::mem::size_of to size_of intrinsic documentation) - #55530 (Speed up String::from_utf16) - #55556 (Use `Mmap` to open the rmeta file.) - #55622 (NetBSD: link libstd with librt in addition to libpthread) - #55750 (Make `NodeId` and `HirLocalId` `newtype_index`) - #55778 (Wrap some query results in `Lrc`.) - #55781 (More precise spans for temps and their drops) - #55785 (Add mem::forget_unsized() for forgetting unsized values) - #55852 (Rewrite `...` as `..=` as a `MachineApplicable` 2018 idiom lint) - #55865 (Unix RwLock: avoid racy access to write_locked) - #55901 (fix various typos in doc comments) - #55926 (Change sidebar selector to fix compatibility with docs.rs) - #55930 (A handful of hir tweaks) - #55932 (core/char: Speed up `to_digit()` for `radix <= 10`) - #55956 (add tests for some fixed ICEs) Failed merges: r? @ghost
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So that the frequent clones in
try_getare cheaper.