From 041121a18434023982b88b0d60f92ee904df4f49 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Gammels=C3=A6ter?= <martin@mg.am>
Date: Wed, 13 Apr 2022 17:46:29 +0200
Subject: [PATCH 1/2] Optimize relate_substs by extracting match
There was no need to keep doing the match inside the iterator.
---
compiler/rustc_middle/src/ty/relate.rs | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs
index d9b55563996ba..b1cfa3fa96433 100644
--- a/compiler/rustc_middle/src/ty/relate.rs
+++ b/compiler/rustc_middle/src/ty/relate.rs
@@ -142,11 +142,12 @@ pub fn relate_substs<'tcx, R: TypeRelation<'tcx>>(
b_subst: SubstsRef<'tcx>,
) -> RelateResult<'tcx, SubstsRef<'tcx>> {
let tcx = relation.tcx();
- let mut cached_ty = None;
- let params = iter::zip(a_subst, b_subst).enumerate().map(|(i, (a, b))| {
- let (variance, variance_info) = match variances {
- Some((ty_def_id, variances)) => {
+ let zipped = iter::zip(a_subst, b_subst);
+ match variances {
+ Some((ty_def_id, variances)) => {
+ let mut cached_ty = None;
+ tcx.mk_substs(zipped.enumerate().map(|(i, (a, b))| {
let variance = variances[i];
let variance_info = if variance == ty::Invariant {
let ty = *cached_ty
@@ -155,14 +156,13 @@ pub fn relate_substs<'tcx, R: TypeRelation<'tcx>>(
} else {
ty::VarianceDiagInfo::default()
};
- (variance, variance_info)
- }
- None => (ty::Invariant, ty::VarianceDiagInfo::default()),
- };
- relation.relate_with_variance(variance, variance_info, a, b)
- });
-
- tcx.mk_substs(params)
+ relation.relate_with_variance(variance, variance_info, a, b)
+ }))
+ }
+ None => tcx.mk_substs(zipped.map(|(a, b)| {
+ relation.relate_with_variance(ty::Invariant, ty::VarianceDiagInfo::default(), a, b)
+ })),
+ }
}
impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> {
From 19dedf3a4b6cfd42ec46949b1d0c4416dd80d11b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Gammels=C3=A6ter?= <martin@mg.am>
Date: Sun, 17 Apr 2022 11:04:58 +0200
Subject: [PATCH 2/2] Split relate_substs into two functions
One for the case with variances, and one without.
All callers use an explicit Option for the variable anyway.
---
compiler/rustc_infer/src/infer/combine.rs | 10 +++-
compiler/rustc_infer/src/infer/equate.rs | 2 +-
compiler/rustc_middle/src/ty/relate.rs | 61 ++++++++++++-----------
3 files changed, 42 insertions(+), 31 deletions(-)
diff --git a/compiler/rustc_infer/src/infer/combine.rs b/compiler/rustc_infer/src/infer/combine.rs
index 86229dbfad746..0ca0fe33614f8 100644
--- a/compiler/rustc_infer/src/infer/combine.rs
+++ b/compiler/rustc_infer/src/infer/combine.rs
@@ -567,11 +567,17 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
// Avoid fetching the variance if we are in an invariant
// context; no need, and it can induce dependency cycles
// (e.g., #41849).
- relate::relate_substs(self, None, a_subst, b_subst)
+ relate::relate_substs(self, a_subst, b_subst)
} else {
let tcx = self.tcx();
let opt_variances = tcx.variances_of(item_def_id);
- relate::relate_substs(self, Some((item_def_id, &opt_variances)), a_subst, b_subst)
+ relate::relate_substs_with_variances(
+ self,
+ item_def_id,
+ &opt_variances,
+ a_subst,
+ b_subst,
+ )
}
}
diff --git a/compiler/rustc_infer/src/infer/equate.rs b/compiler/rustc_infer/src/infer/equate.rs
index 65c0eba4b3d5c..ef6d464d3c6f1 100644
--- a/compiler/rustc_infer/src/infer/equate.rs
+++ b/compiler/rustc_infer/src/infer/equate.rs
@@ -53,7 +53,7 @@ impl<'tcx> TypeRelation<'tcx> for Equate<'_, '_, 'tcx> {
// performing trait matching (which then performs equality
// unification).
- relate::relate_substs(self, None, a_subst, b_subst)
+ relate::relate_substs(self, a_subst, b_subst)
}
fn relate_with_variance<T: Relate<'tcx>>(
diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs
index b1cfa3fa96433..4c1160e21fec2 100644
--- a/compiler/rustc_middle/src/ty/relate.rs
+++ b/compiler/rustc_middle/src/ty/relate.rs
@@ -61,7 +61,7 @@ pub trait TypeRelation<'tcx>: Sized {
let tcx = self.tcx();
let opt_variances = tcx.variances_of(item_def_id);
- relate_substs(self, Some((item_def_id, opt_variances)), a_subst, b_subst)
+ relate_substs_with_variances(self, item_def_id, opt_variances, a_subst, b_subst)
}
/// Switch variance for the purpose of relating `a` and `b`.
@@ -135,34 +135,39 @@ pub fn relate_type_and_mut<'tcx, R: TypeRelation<'tcx>>(
}
}
+#[inline]
pub fn relate_substs<'tcx, R: TypeRelation<'tcx>>(
relation: &mut R,
- variances: Option<(DefId, &[ty::Variance])>,
+ a_subst: SubstsRef<'tcx>,
+ b_subst: SubstsRef<'tcx>,
+) -> RelateResult<'tcx, SubstsRef<'tcx>> {
+ relation.tcx().mk_substs(iter::zip(a_subst, b_subst).map(|(a, b)| {
+ relation.relate_with_variance(ty::Invariant, ty::VarianceDiagInfo::default(), a, b)
+ }))
+}
+
+pub fn relate_substs_with_variances<'tcx, R: TypeRelation<'tcx>>(
+ relation: &mut R,
+ ty_def_id: DefId,
+ variances: &[ty::Variance],
a_subst: SubstsRef<'tcx>,
b_subst: SubstsRef<'tcx>,
) -> RelateResult<'tcx, SubstsRef<'tcx>> {
let tcx = relation.tcx();
- let zipped = iter::zip(a_subst, b_subst);
- match variances {
- Some((ty_def_id, variances)) => {
- let mut cached_ty = None;
- tcx.mk_substs(zipped.enumerate().map(|(i, (a, b))| {
- let variance = variances[i];
- let variance_info = if variance == ty::Invariant {
- let ty = *cached_ty
- .get_or_insert_with(|| tcx.type_of(ty_def_id).subst(tcx, a_subst));
- ty::VarianceDiagInfo::Invariant { ty, param_index: i.try_into().unwrap() }
- } else {
- ty::VarianceDiagInfo::default()
- };
- relation.relate_with_variance(variance, variance_info, a, b)
- }))
- }
- None => tcx.mk_substs(zipped.map(|(a, b)| {
- relation.relate_with_variance(ty::Invariant, ty::VarianceDiagInfo::default(), a, b)
- })),
- }
+ let mut cached_ty = None;
+ let params = iter::zip(a_subst, b_subst).enumerate().map(|(i, (a, b))| {
+ let variance = variances[i];
+ let variance_info = if variance == ty::Invariant {
+ let ty = *cached_ty.get_or_insert_with(|| tcx.type_of(ty_def_id).subst(tcx, a_subst));
+ ty::VarianceDiagInfo::Invariant { ty, param_index: i.try_into().unwrap() }
+ } else {
+ ty::VarianceDiagInfo::default()
+ };
+ relation.relate_with_variance(variance, variance_info, a, b)
+ });
+
+ tcx.mk_substs(params)
}
impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> {
@@ -318,7 +323,7 @@ impl<'tcx> Relate<'tcx> for ty::TraitRef<'tcx> {
if a.def_id != b.def_id {
Err(TypeError::Traits(expected_found(relation, a.def_id, b.def_id)))
} else {
- let substs = relate_substs(relation, None, a.substs, b.substs)?;
+ let substs = relate_substs(relation, a.substs, b.substs)?;
Ok(ty::TraitRef { def_id: a.def_id, substs })
}
}
@@ -334,7 +339,7 @@ impl<'tcx> Relate<'tcx> for ty::ExistentialTraitRef<'tcx> {
if a.def_id != b.def_id {
Err(TypeError::Traits(expected_found(relation, a.def_id, b.def_id)))
} else {
- let substs = relate_substs(relation, None, a.substs, b.substs)?;
+ let substs = relate_substs(relation, a.substs, b.substs)?;
Ok(ty::ExistentialTraitRef { def_id: a.def_id, substs })
}
}
@@ -554,7 +559,7 @@ pub fn super_relate_tys<'tcx, R: TypeRelation<'tcx>>(
(&ty::Opaque(a_def_id, a_substs), &ty::Opaque(b_def_id, b_substs))
if a_def_id == b_def_id =>
{
- let substs = relate_substs(relation, None, a_substs, b_substs)?;
+ let substs = relate_substs(relation, a_substs, b_substs)?;
Ok(tcx.mk_opaque(a_def_id, substs))
}
@@ -742,7 +747,7 @@ impl<'tcx> Relate<'tcx> for ty::ClosureSubsts<'tcx> {
a: ty::ClosureSubsts<'tcx>,
b: ty::ClosureSubsts<'tcx>,
) -> RelateResult<'tcx, ty::ClosureSubsts<'tcx>> {
- let substs = relate_substs(relation, None, a.substs, b.substs)?;
+ let substs = relate_substs(relation, a.substs, b.substs)?;
Ok(ty::ClosureSubsts { substs })
}
}
@@ -753,7 +758,7 @@ impl<'tcx> Relate<'tcx> for ty::GeneratorSubsts<'tcx> {
a: ty::GeneratorSubsts<'tcx>,
b: ty::GeneratorSubsts<'tcx>,
) -> RelateResult<'tcx, ty::GeneratorSubsts<'tcx>> {
- let substs = relate_substs(relation, None, a.substs, b.substs)?;
+ let substs = relate_substs(relation, a.substs, b.substs)?;
Ok(ty::GeneratorSubsts { substs })
}
}
@@ -764,7 +769,7 @@ impl<'tcx> Relate<'tcx> for SubstsRef<'tcx> {
a: SubstsRef<'tcx>,
b: SubstsRef<'tcx>,
) -> RelateResult<'tcx, SubstsRef<'tcx>> {
- relate_substs(relation, None, a, b)
+ relate_substs(relation, a, b)
}
}