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Auto merge of #59540 - Zoxc:the-arena-2, r=<try>
[WIP] Use arenas to avoid Lrc in queries #1 Based on #59536.
2 parents 99da733 + 9c3de34 commit f426a56

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12 files changed

+81
-90
lines changed

12 files changed

+81
-90
lines changed

‎Cargo.lock

+1
Original file line numberDiff line numberDiff line change
@@ -2812,6 +2812,7 @@ dependencies = [
28122812
"rustc_errors 0.0.0",
28132813
"rustc_target 0.0.0",
28142814
"serialize 0.0.0",
2815+
"smallvec 0.6.7 (registry+https://github.com/rust-lang/crates.io-index)",
28152816
"stable_deref_trait 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
28162817
"syntax 0.0.0",
28172818
"syntax_ext 0.0.0",

‎src/librustc/arena.rs

+1
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,7 @@ macro_rules! arena_types {
1616
)>,
1717
[few] mir_keys: rustc::util::nodemap::DefIdSet,
1818
[decode] specialization_graph: rustc::traits::specialization_graph::Graph,
19+
[few] crate_inherent_impls: rustc::ty::CrateInherentImpls,
1920
], $tcx);
2021
)
2122
}

‎src/librustc/query/mod.rs

+6-6
Original file line numberDiff line numberDiff line change
@@ -174,7 +174,7 @@ rustc_queries! {
174174

175175
/// Returns the inferred outlives predicates (e.g., for `struct
176176
/// Foo<'a, T> { x: &'a T }`, this would return `T: 'a`).
177-
query inferred_outlives_of(_: DefId) -> Lrc<Vec<ty::Predicate<'tcx>>> {}
177+
query inferred_outlives_of(_: DefId) -> &'tcx [ty::Predicate<'tcx>] {}
178178

179179
/// Maps from the `DefId` of a trait to the list of
180180
/// super-predicates. This is a subset of the full list of
@@ -240,13 +240,13 @@ rustc_queries! {
240240

241241
/// Get a map with the variance of every item; use `item_variance`
242242
/// instead.
243-
query crate_variances(_: CrateNum) -> Lrc<ty::CrateVariancesMap> {
243+
query crate_variances(_: CrateNum) -> Lrc<ty::CrateVariancesMap<'tcx>> {
244244
desc { "computing the variances for items in this crate" }
245245
}
246246

247247
/// Maps from def-id of a type or region parameter to its
248248
/// (inferred) variance.
249-
query variances_of(_: DefId) -> Lrc<Vec<ty::Variance>> {}
249+
query variances_of(_: DefId) -> &'tcx [ty::Variance] {}
250250
}
251251

252252
TypeChecking {
@@ -259,7 +259,7 @@ rustc_queries! {
259259

260260
Other {
261261
/// Maps from an impl/trait def-id to a list of the def-ids of its items
262-
query associated_item_def_ids(_: DefId) -> Lrc<Vec<DefId>> {}
262+
query associated_item_def_ids(_: DefId) -> &'tcx [DefId] {}
263263

264264
/// Maps from a trait item to the trait item "descriptor"
265265
query associated_item(_: DefId) -> ty::AssociatedItem {}
@@ -274,7 +274,7 @@ rustc_queries! {
274274
/// Maps a DefId of a type to a list of its inherent impls.
275275
/// Contains implementations of methods that are inherent to a type.
276276
/// Methods in these implementations don't need to be exported.
277-
query inherent_impls(_: DefId) -> Lrc<Vec<DefId>> {
277+
query inherent_impls(_: DefId) -> &'tcx [DefId] {
278278
eval_always
279279
}
280280
}
@@ -380,7 +380,7 @@ rustc_queries! {
380380
/// Not meant to be used directly outside of coherence.
381381
/// (Defined only for `LOCAL_CRATE`.)
382382
query crate_inherent_impls(k: CrateNum)
383-
-> Lrc<CrateInherentImpls> {
383+
-> &'tcx CrateInherentImpls {
384384
eval_always
385385
desc { "all inherent impls defined in crate `{:?}`", k }
386386
}

‎src/librustc/ty/mod.rs

+19-26
Original file line numberDiff line numberDiff line change
@@ -330,15 +330,11 @@ pub enum Variance {
330330
/// `tcx.variances_of()` to get the variance for a *particular*
331331
/// item.
332332
#[derive(HashStable)]
333-
pub struct CrateVariancesMap {
333+
pub struct CrateVariancesMap<'tcx> {
334334
/// For each item with generics, maps to a vector of the variance
335335
/// of its generics. If an item has no generics, it will have no
336336
/// entry.
337-
pub variances: FxHashMap<DefId, Lrc<Vec<ty::Variance>>>,
338-
339-
/// An empty vector, useful for cloning.
340-
#[stable_hasher(ignore)]
341-
pub empty_variance: Lrc<Vec<ty::Variance>>,
337+
pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
342338
}
343339

344340
impl Variance {
@@ -1110,11 +1106,7 @@ pub struct CratePredicatesMap<'tcx> {
11101106
/// For each struct with outlive bounds, maps to a vector of the
11111107
/// predicate of its outlive bounds. If an item has no outlives
11121108
/// bounds, it will have no entry.
1113-
pub predicates: FxHashMap<DefId, Lrc<Vec<ty::Predicate<'tcx>>>>,
1114-
1115-
/// An empty vector, useful for cloning.
1116-
#[stable_hasher(ignore)]
1117-
pub empty_predicate: Lrc<Vec<ty::Predicate<'tcx>>>,
1109+
pub predicates: FxHashMap<DefId, &'tcx [ty::Predicate<'tcx>]>,
11181110
}
11191111

11201112
impl<'tcx> AsRef<Predicate<'tcx>> for Predicate<'tcx> {
@@ -3091,7 +3083,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
30913083

30923084
pub struct AssociatedItemsIterator<'a, 'gcx: 'tcx, 'tcx: 'a> {
30933085
tcx: TyCtxt<'a, 'gcx, 'tcx>,
3094-
def_ids: Lrc<Vec<DefId>>,
3086+
def_ids: &'gcx [DefId],
30953087
next_index: usize,
30963088
}
30973089

@@ -3180,26 +3172,27 @@ fn adt_sized_constraint<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
31803172

31813173
fn associated_item_def_ids<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
31823174
def_id: DefId)
3183-
-> Lrc<Vec<DefId>> {
3175+
-> &'tcx [DefId] {
31843176
let id = tcx.hir().as_local_hir_id(def_id).unwrap();
31853177
let item = tcx.hir().expect_item_by_hir_id(id);
3186-
let vec: Vec<_> = match item.node {
3178+
match item.node {
31873179
hir::ItemKind::Trait(.., ref trait_item_refs) => {
3188-
trait_item_refs.iter()
3189-
.map(|trait_item_ref| trait_item_ref.id)
3190-
.map(|id| tcx.hir().local_def_id_from_hir_id(id.hir_id))
3191-
.collect()
3180+
tcx.arena.alloc_from_iter(
3181+
trait_item_refs.iter()
3182+
.map(|trait_item_ref| trait_item_ref.id)
3183+
.map(|id| tcx.hir().local_def_id_from_hir_id(id.hir_id))
3184+
)
31923185
}
31933186
hir::ItemKind::Impl(.., ref impl_item_refs) => {
3194-
impl_item_refs.iter()
3195-
.map(|impl_item_ref| impl_item_ref.id)
3196-
.map(|id| tcx.hir().local_def_id_from_hir_id(id.hir_id))
3197-
.collect()
3187+
tcx.arena.alloc_from_iter(
3188+
impl_item_refs.iter()
3189+
.map(|impl_item_ref| impl_item_ref.id)
3190+
.map(|id| tcx.hir().local_def_id_from_hir_id(id.hir_id))
3191+
)
31983192
}
3199-
hir::ItemKind::TraitAlias(..) => vec![],
3193+
hir::ItemKind::TraitAlias(..) => &[],
32003194
_ => span_bug!(item.span, "associated_item_def_ids: not impl or trait")
3201-
};
3202-
Lrc::new(vec)
3195+
}
32033196
}
32043197

32053198
fn def_span<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Span {
@@ -3385,7 +3378,7 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
33853378
/// (constructing this map requires touching the entire crate).
33863379
#[derive(Clone, Debug, Default, HashStable)]
33873380
pub struct CrateInherentImpls {
3388-
pub inherent_impls: DefIdMap<Lrc<Vec<DefId>>>,
3381+
pub inherent_impls: DefIdMap<Vec<DefId>>,
33893382
}
33903383

33913384
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable)]

‎src/librustc/ty/relate.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -60,7 +60,7 @@ pub trait TypeRelation<'a, 'gcx: 'a+'tcx, 'tcx: 'a> : Sized {
6060
b_subst);
6161

6262
let opt_variances = self.tcx().variances_of(item_def_id);
63-
relate_substs(self, Some(&opt_variances), a_subst, b_subst)
63+
relate_substs(self, Some(opt_variances), a_subst, b_subst)
6464
}
6565

6666
/// Switch variance for the purpose of relating `a` and `b`.
@@ -122,7 +122,7 @@ impl<'tcx> Relate<'tcx> for ty::TypeAndMut<'tcx> {
122122
}
123123

124124
pub fn relate_substs<'a, 'gcx, 'tcx, R>(relation: &mut R,
125-
variances: Option<&Vec<ty::Variance>>,
125+
variances: Option<&[ty::Variance]>,
126126
a_subst: SubstsRef<'tcx>,
127127
b_subst: SubstsRef<'tcx>)
128128
-> RelateResult<'tcx, SubstsRef<'tcx>>

‎src/librustc_metadata/Cargo.toml

+1
Original file line numberDiff line numberDiff line change
@@ -13,6 +13,7 @@ crate-type = ["dylib"]
1313
flate2 = "1.0"
1414
log = "0.4"
1515
memmap = "0.6"
16+
smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
1617
rustc = { path = "../librustc" }
1718
rustc_data_structures = { path = "../librustc_data_structures" }
1819
errors = { path = "../librustc_errors", package = "rustc_errors" }

‎src/librustc_metadata/cstore_impl.rs

+5-4
Original file line numberDiff line numberDiff line change
@@ -20,6 +20,7 @@ use rustc::hir::map::definitions::DefPathTable;
2020
use rustc::util::nodemap::DefIdMap;
2121
use rustc_data_structures::svh::Svh;
2222

23+
use smallvec::SmallVec;
2324
use std::any::Any;
2425
use rustc_data_structures::sync::Lrc;
2526
use std::sync::Arc;
@@ -105,12 +106,12 @@ provide! { <'tcx> tcx, def_id, other, cdata,
105106
let _ = cdata;
106107
tcx.calculate_dtor(def_id, &mut |_,_| Ok(()))
107108
}
108-
variances_of => { Lrc::new(cdata.get_item_variances(def_id.index)) }
109+
variances_of => { tcx.arena.alloc_from_iter(cdata.get_item_variances(def_id.index)) }
109110
associated_item_def_ids => {
110-
let mut result = vec![];
111+
let mut result = SmallVec::<[_; 8]>::new();
111112
cdata.each_child_of_item(def_id.index,
112113
|child| result.push(child.def.def_id()), tcx.sess);
113-
Lrc::new(result)
114+
tcx.arena.alloc_from_iter(result)
114115
}
115116
associated_item => { cdata.get_associated_item(def_id.index) }
116117
impl_trait_ref => { cdata.get_impl_trait(def_id.index, tcx) }
@@ -133,7 +134,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
133134
(cdata.mir_const_qualif(def_id.index), Lrc::new(BitSet::new_empty(0)))
134135
}
135136
fn_sig => { cdata.fn_sig(def_id.index, tcx) }
136-
inherent_impls => { Lrc::new(cdata.get_inherent_implementations_for_type(def_id.index)) }
137+
inherent_impls => { cdata.get_inherent_implementations_for_type(tcx, def_id.index) }
137138
is_const_fn_raw => { cdata.is_const_fn_raw(def_id.index) }
138139
is_foreign_item => { cdata.is_foreign_item(def_id.index) }
139140
describe_def => { cdata.get_def(def_id.index) }

‎src/librustc_metadata/decoder.rs

+9-6
Original file line numberDiff line numberDiff line change
@@ -998,12 +998,15 @@ impl<'a, 'tcx> CrateMetadata {
998998
None
999999
}
10001000

1001-
pub fn get_inherent_implementations_for_type(&self, id: DefIndex) -> Vec<DefId> {
1002-
self.entry(id)
1003-
.inherent_impls
1004-
.decode(self)
1005-
.map(|index| self.local_def_id(index))
1006-
.collect()
1001+
pub fn get_inherent_implementations_for_type(
1002+
&self,
1003+
tcx: TyCtxt<'_, 'tcx, '_>,
1004+
id: DefIndex
1005+
) -> &'tcx [DefId] {
1006+
tcx.arena.alloc_from_iter(self.entry(id)
1007+
.inherent_impls
1008+
.decode(self)
1009+
.map(|index| self.local_def_id(index)))
10071010
}
10081011

10091012
pub fn get_implementations_for_trait(&self,

‎src/librustc_typeck/coherence/inherent_impls.rs

+7-17
Original file line numberDiff line numberDiff line change
@@ -13,14 +13,13 @@ use rustc::hir;
1313
use rustc::hir::itemlikevisit::ItemLikeVisitor;
1414
use rustc::ty::{self, CrateInherentImpls, TyCtxt};
1515

16-
use rustc_data_structures::sync::Lrc;
1716
use syntax::ast;
1817
use syntax_pos::Span;
1918

2019
/// On-demand query: yields a map containing all types mapped to their inherent impls.
2120
pub fn crate_inherent_impls<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2221
crate_num: CrateNum)
23-
-> Lrc<CrateInherentImpls> {
22+
-> &'tcx CrateInherentImpls {
2423
assert_eq!(crate_num, LOCAL_CRATE);
2524

2625
let krate = tcx.hir().krate();
@@ -29,13 +28,13 @@ pub fn crate_inherent_impls<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2928
impls_map: Default::default(),
3029
};
3130
krate.visit_all_item_likes(&mut collect);
32-
Lrc::new(collect.impls_map)
31+
tcx.arena.alloc(collect.impls_map)
3332
}
3433

3534
/// On-demand query: yields a vector of the inherent impls for a specific type.
3635
pub fn inherent_impls<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
3736
ty_def_id: DefId)
38-
-> Lrc<Vec<DefId>> {
37+
-> &'tcx [DefId] {
3938
assert!(ty_def_id.is_local());
4039

4140
// NB. Until we adopt the red-green dep-tracking algorithm (see
@@ -53,15 +52,11 @@ pub fn inherent_impls<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
5352
//
5453
// [the plan]: https://github.com/rust-lang/rust-roadmap/issues/4
5554

56-
thread_local! {
57-
static EMPTY_DEF_ID_VEC: Lrc<Vec<DefId>> = Lrc::new(vec![])
58-
}
59-
6055
let result = tcx.dep_graph.with_ignore(|| {
6156
let crate_map = tcx.crate_inherent_impls(ty_def_id.krate);
6257
match crate_map.inherent_impls.get(&ty_def_id) {
63-
Some(v) => v.clone(),
64-
None => EMPTY_DEF_ID_VEC.with(|v| v.clone())
58+
Some(v) => &v[..],
59+
None => &[],
6560
}
6661
});
6762

@@ -289,13 +284,8 @@ impl<'a, 'tcx> InherentCollect<'a, 'tcx> {
289284
// type def ID, if there is a base type for this implementation and
290285
// the implementation does not have any associated traits.
291286
let impl_def_id = self.tcx.hir().local_def_id_from_hir_id(item.hir_id);
292-
let mut rc_vec = self.impls_map.inherent_impls
293-
.entry(def_id)
294-
.or_default();
295-
296-
// At this point, there should not be any clones of the
297-
// `Lrc`, so we can still safely push into it in place:
298-
Lrc::get_mut(&mut rc_vec).unwrap().push(impl_def_id);
287+
let vec = self.impls_map.inherent_impls.entry(def_id).or_default();
288+
vec.push(impl_def_id);
299289
} else {
300290
struct_span_err!(self.tcx.sess,
301291
item.span,

‎src/librustc_typeck/outlives/mod.rs

+8-11
Original file line numberDiff line numberDiff line change
@@ -23,7 +23,7 @@ pub fn provide(providers: &mut Providers<'_>) {
2323
fn inferred_outlives_of<'a, 'tcx>(
2424
tcx: TyCtxt<'a, 'tcx, 'tcx>,
2525
item_def_id: DefId,
26-
) -> Lrc<Vec<ty::Predicate<'tcx>>> {
26+
) -> &'tcx [ty::Predicate<'tcx>] {
2727
let id = tcx
2828
.hir()
2929
.as_local_hir_id(item_def_id)
@@ -37,8 +37,8 @@ fn inferred_outlives_of<'a, 'tcx>(
3737
let predicates = crate_map
3838
.predicates
3939
.get(&item_def_id)
40-
.unwrap_or(&crate_map.empty_predicate)
41-
.clone();
40+
.map(|p| *p)
41+
.unwrap_or(&[]);
4242

4343
if tcx.has_attr(item_def_id, "rustc_outlives") {
4444
let mut pred: Vec<String> = predicates
@@ -63,10 +63,10 @@ fn inferred_outlives_of<'a, 'tcx>(
6363
predicates
6464
}
6565

66-
_ => Lrc::new(Vec::new()),
66+
_ => &[],
6767
},
6868

69-
_ => Lrc::new(Vec::new()),
69+
_ => &[],
7070
}
7171
}
7272

@@ -96,7 +96,7 @@ fn inferred_outlives_crate<'tcx>(
9696
let predicates = global_inferred_outlives
9797
.iter()
9898
.map(|(&def_id, set)| {
99-
let vec: Vec<ty::Predicate<'tcx>> = set
99+
let predicates = tcx.arena.alloc_from_iter(set
100100
.iter()
101101
.filter_map(
102102
|ty::OutlivesPredicate(kind1, region2)| match kind1.unpack() {
@@ -115,14 +115,11 @@ fn inferred_outlives_crate<'tcx>(
115115
None
116116
}
117117
},
118-
).collect();
119-
(def_id, Lrc::new(vec))
118+
));
119+
(def_id, &*predicates)
120120
}).collect();
121121

122-
let empty_predicate = Lrc::new(Vec::new());
123-
124122
Lrc::new(ty::CratePredicatesMap {
125123
predicates,
126-
empty_predicate,
127124
})
128125
}

‎src/librustc_typeck/variance/mod.rs

+4-4
Original file line numberDiff line numberDiff line change
@@ -36,7 +36,7 @@ pub fn provide(providers: &mut Providers<'_>) {
3636
}
3737

3838
fn crate_variances<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, crate_num: CrateNum)
39-
-> Lrc<CrateVariancesMap> {
39+
-> Lrc<CrateVariancesMap<'tcx>> {
4040
assert_eq!(crate_num, LOCAL_CRATE);
4141
let mut arena = arena::TypedArena::default();
4242
let terms_cx = terms::determine_parameters_to_be_inferred(tcx, &mut arena);
@@ -45,7 +45,7 @@ fn crate_variances<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, crate_num: CrateNum)
4545
}
4646

4747
fn variances_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_def_id: DefId)
48-
-> Lrc<Vec<ty::Variance>> {
48+
-> &'tcx [ty::Variance] {
4949
let id = tcx.hir().as_local_hir_id(item_def_id).expect("expected local def-id");
5050
let unsupported = || {
5151
// Variance not relevant.
@@ -88,6 +88,6 @@ fn variances_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_def_id: DefId)
8888

8989
let crate_map = tcx.crate_variances(LOCAL_CRATE);
9090
crate_map.variances.get(&item_def_id)
91-
.unwrap_or(&crate_map.empty_variance)
92-
.clone()
91+
.map(|p| *p)
92+
.unwrap_or(&[])
9393
}

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