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mir_build: Avoid some useless work when visiting "primary" bindings #137465

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merged 4 commits into from
Mar 17, 2025
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Merged

mir_build: Avoid some useless work when visiting "primary" bindings #137465

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bca5f56
Add a mir-opt test that demonstrates user type annotations
Zalathar Feb 23, 2025
977106a
Simplify handling of `visibility_scope` in `declare_bindings`
Zalathar Feb 16, 2025
7805b46
Split `visit_primary_bindings` into two variants
Zalathar Feb 15, 2025
5434242
Build `UserTypeProjections` lazily when visiting bindings
Zalathar Feb 20, 2025
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85 changes: 3 additions & 82 deletions compiler/rustc_middle/src/mir/mod.rs
View file
Original file line number Diff line number Diff line change
@@ -33,8 +33,8 @@ use crate::mir::interpret::{AllocRange, Scalar};
use crate::ty::codec::{TyDecoder, TyEncoder};
use crate::ty::print::{FmtPrinter, Printer, pretty_print_const, with_no_trimmed_paths};
use crate::ty::{
self, AdtDef, GenericArg, GenericArgsRef, Instance, InstanceKind, List, Ty, TyCtxt,
TypeVisitableExt, TypingEnv, UserTypeAnnotationIndex,
self, GenericArg, GenericArgsRef, Instance, InstanceKind, List, Ty, TyCtxt, TypeVisitableExt,
TypingEnv, UserTypeAnnotationIndex,
};

mod basic_blocks;
@@ -1482,53 +1482,10 @@ pub struct UserTypeProjections {
pub contents: Vec<UserTypeProjection>,
}

impl<'tcx> UserTypeProjections {
pub fn none() -> Self {
UserTypeProjections { contents: vec![] }
}

pub fn is_empty(&self) -> bool {
self.contents.is_empty()
}

impl UserTypeProjections {
pub fn projections(&self) -> impl Iterator<Item = &UserTypeProjection> + ExactSizeIterator {
self.contents.iter()
}

pub fn push_user_type(mut self, base_user_type: UserTypeAnnotationIndex) -> Self {
self.contents.push(UserTypeProjection { base: base_user_type, projs: vec![] });
self
}

fn map_projections(mut self, f: impl FnMut(UserTypeProjection) -> UserTypeProjection) -> Self {
self.contents = self.contents.into_iter().map(f).collect();
self
}

pub fn index(self) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.index())
}

pub fn subslice(self, from: u64, to: u64) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.subslice(from, to))
}

pub fn deref(self) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.deref())
}

pub fn leaf(self, field: FieldIdx) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.leaf(field))
}

pub fn variant(
self,
adt_def: AdtDef<'tcx>,
variant_index: VariantIdx,
field_index: FieldIdx,
) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.variant(adt_def, variant_index, field_index))
}
}

/// Encodes the effect of a user-supplied type annotation on the
@@ -1553,42 +1510,6 @@ pub struct UserTypeProjection {
pub projs: Vec<ProjectionKind>,
}

impl UserTypeProjection {
pub(crate) fn index(mut self) -> Self {
self.projs.push(ProjectionElem::Index(()));
self
}

pub(crate) fn subslice(mut self, from: u64, to: u64) -> Self {
self.projs.push(ProjectionElem::Subslice { from, to, from_end: true });
self
}

pub(crate) fn deref(mut self) -> Self {
self.projs.push(ProjectionElem::Deref);
self
}

pub(crate) fn leaf(mut self, field: FieldIdx) -> Self {
self.projs.push(ProjectionElem::Field(field, ()));
self
}

pub(crate) fn variant(
mut self,
adt_def: AdtDef<'_>,
variant_index: VariantIdx,
field_index: FieldIdx,
) -> Self {
self.projs.push(ProjectionElem::Downcast(
Some(adt_def.variant(variant_index).name),
variant_index,
));
self.projs.push(ProjectionElem::Field(field_index, ()));
self
}
}

rustc_index::newtype_index! {
#[derive(HashStable)]
#[encodable]
4 changes: 4 additions & 0 deletions compiler/rustc_middle/src/thir.rs
View file
Original file line number Diff line number Diff line change
@@ -783,8 +783,12 @@ pub enum PatKind<'tcx> {
var: LocalVarId,
ty: Ty<'tcx>,
subpattern: Option<Box<Pat<'tcx>>>,

/// Is this the leftmost occurrence of the binding, i.e., is `var` the
/// `HirId` of this pattern?
///
/// (The same binding can occur multiple times in different branches of
/// an or-pattern, but only one of them will be primary.)
is_primary: bool,
},

46 changes: 19 additions & 27 deletions compiler/rustc_mir_build/src/builder/block.rs
View file
Original file line number Diff line number Diff line change
@@ -199,19 +199,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
None,
Some((Some(&destination), initializer_span)),
);
this.visit_primary_bindings(
pattern,
UserTypeProjections::none(),
&mut |this, _, _, node, span, _, _| {
this.storage_live_binding(
block,
node,
span,
OutsideGuard,
ScheduleDrops::Yes,
);
},
);
this.visit_primary_bindings(pattern, &mut |this, node, span| {
this.storage_live_binding(
block,
node,
span,
OutsideGuard,
ScheduleDrops::Yes,
);
});
let else_block_span = this.thir[*else_block].span;
let (matching, failure) =
this.in_if_then_scope(last_remainder_scope, else_block_span, |this| {
@@ -295,20 +291,16 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
});

debug!("ast_block_stmts: pattern={:?}", pattern);
this.visit_primary_bindings(
pattern,
UserTypeProjections::none(),
&mut |this, _, _, node, span, _, _| {
this.storage_live_binding(
block,
node,
span,
OutsideGuard,
ScheduleDrops::Yes,
);
this.schedule_drop_for_binding(node, span, OutsideGuard);
},
)
this.visit_primary_bindings(pattern, &mut |this, node, span| {
this.storage_live_binding(
block,
node,
span,
OutsideGuard,
ScheduleDrops::Yes,
);
this.schedule_drop_for_binding(node, span, OutsideGuard);
})
}

// Enter the visibility scope, after evaluating the initializer.
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