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Introduce ProjectionElem::try_map.

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This commit is contained in:
Camille GILLOT
2025-07-02 11:56:57 +00:00
committed by Camille Gillot
parent 040a98af70
commit 37e7f52876
6 changed files with 67 additions and 93 deletions
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38
compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs
View File

@@ -1,38 +0,0 @@
//! The move-analysis portion of borrowck needs to work in an abstract
//! domain of lifted `Place`s. Most of the `Place` variants fall into a
//! one-to-one mapping between the concrete and abstract (e.g., a
//! field-deref on a local variable, `x.field`, has the same meaning
//! in both domains). Indexed projections are the exception: `a[x]`
//! needs to be treated as mapping to the same move path as `a[y]` as
//! well as `a[13]`, etc. So we map these `x`/`y` values to `()`.
//!
//! (In theory, the analysis could be extended to work with sets of
//! paths, so that `a[0]` and `a[13]` could be kept distinct, while
//! `a[x]` would still overlap them both. But that is not this
//! representation does today.)
use rustc_middle::mir::{PlaceElem, ProjectionElem, ProjectionKind};
pub(crate) trait Lift {
fn lift(&self) -> ProjectionKind;
}
impl<'tcx> Lift for PlaceElem<'tcx> {
fn lift(&self) -> ProjectionKind {
match *self {
ProjectionElem::Deref => ProjectionElem::Deref,
ProjectionElem::Field(f, _ty) => ProjectionElem::Field(f, ()),
ProjectionElem::OpaqueCast(_ty) => ProjectionElem::OpaqueCast(()),
ProjectionElem::Index(_i) => ProjectionElem::Index(()),
ProjectionElem::Subslice { from, to, from_end } => {
ProjectionElem::Subslice { from, to, from_end }
}
ProjectionElem::ConstantIndex { offset, min_length, from_end } => {
ProjectionElem::ConstantIndex { offset, min_length, from_end }
}
ProjectionElem::Downcast(a, u) => ProjectionElem::Downcast(a, u),
ProjectionElem::Subtype(_ty) => ProjectionElem::Subtype(()),
ProjectionElem::UnwrapUnsafeBinder(_ty) => ProjectionElem::UnwrapUnsafeBinder(()),
}
}
}

5
compiler/rustc_mir_dataflow/src/move_paths/builder.rs
View File

@@ -7,7 +7,6 @@ use rustc_middle::{bug, span_bug};
use smallvec::{SmallVec, smallvec};
use tracing::debug;
use super::abs_domain::Lift;
use super::{
Init, InitIndex, InitKind, InitLocation, LocationMap, LookupResult, MoveData, MoveOut,
MoveOutIndex, MovePath, MovePathIndex, MovePathLookup,
@@ -241,7 +240,7 @@ impl<'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> MoveDataBuilder<'a, 'tcx, F> {
if union_path.is_none() {
// inlined from add_move_path because of a borrowck conflict with the iterator
base =
*data.rev_lookup.projections.entry((base, elem.lift())).or_insert_with(|| {
*data.rev_lookup.projections.entry((base, elem.kind())).or_insert_with(|| {
new_move_path(
&mut data.move_paths,
&mut data.path_map,
@@ -272,7 +271,7 @@ impl<'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> MoveDataBuilder<'a, 'tcx, F> {
tcx,
..
} = self;
*rev_lookup.projections.entry((base, elem.lift())).or_insert_with(move || {
*rev_lookup.projections.entry((base, elem.kind())).or_insert_with(move || {
new_move_path(move_paths, path_map, init_path_map, Some(base), mk_place(*tcx))
})
}

18
compiler/rustc_mir_dataflow/src/move_paths/mod.rs
View File

@@ -1,3 +1,16 @@
//! The move-analysis portion of borrowck needs to work in an abstract
//! domain of lifted `Place`s. Most of the `Place` variants fall into a
//! one-to-one mapping between the concrete and abstract (e.g., a
//! field-deref on a local variable, `x.field`, has the same meaning
//! in both domains). Indexed projections are the exception: `a[x]`
//! needs to be treated as mapping to the same move path as `a[y]` as
//! well as `a[13]`, etc. So we map these `x`/`y` values to `()`.
//!
//! (In theory, the analysis could be extended to work with sets of
//! paths, so that `a[0]` and `a[13]` could be kept distinct, while
//! `a[x]` would still overlap them both. But that is not this
//! representation does today.)
use std::fmt;
use std::ops::{Index, IndexMut};
@@ -8,11 +21,8 @@ use rustc_middle::ty::{Ty, TyCtxt};
use rustc_span::Span;
use smallvec::SmallVec;
use self::abs_domain::Lift;
use crate::un_derefer::UnDerefer;
mod abs_domain;
rustc_index::newtype_index! {
#[orderable]
#[debug_format = "mp{}"]
@@ -324,7 +334,7 @@ impl<'tcx> MovePathLookup<'tcx> {
};
for (_, elem) in self.un_derefer.iter_projections(place) {
if let Some(&subpath) = self.projections.get(&(result, elem.lift())) {
if let Some(&subpath) = self.projections.get(&(result, elem.kind())) {
result = subpath;
} else {
return LookupResult::Parent(Some(result));