bjoernager/rust
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Dereference immutable borrows in GVN.

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This commit is contained in:
Camille GILLOT 2024-01-05 21:52:58 +00:00
parent 73db12a223
commit 9b846d4637
10 changed files with 87 additions and 47 deletions
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16
compiler/rustc_mir_transform/src/gvn.rs
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@ -724,6 +724,14 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
// Invariant: `value` holds the value up-to the `index`th projection excluded.
let mut value = self.locals[place.local]?;
for (index, proj) in place.projection.iter().enumerate() {
if let Value::Projection(pointer, ProjectionElem::Deref) = *self.get(value)
&& let Value::Address { place: mut pointee, kind, .. } = *self.get(pointer)
&& let AddressKind::Ref(BorrowKind::Shared) = kind
&& let Some(v) = self.simplify_place_value(&mut pointee, location)
{
value = v;
place_ref = pointee.project_deeper(&place.projection[index..], self.tcx).as_ref();
}
if let Some(local) = self.try_as_local(value, location) {
// Both `local` and `Place { local: place.local, projection: projection[..index] }`
// hold the same value. Therefore, following place holds the value in the original
@ -735,6 +743,14 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
value = self.project(base, value, proj)?;
}
if let Value::Projection(pointer, ProjectionElem::Deref) = *self.get(value)
&& let Value::Address { place: mut pointee, kind, .. } = *self.get(pointer)
&& let AddressKind::Ref(BorrowKind::Shared) = kind
&& let Some(v) = self.simplify_place_value(&mut pointee, location)
{
value = v;
place_ref = pointee.project_deeper(&[], self.tcx).as_ref();
}
if let Some(new_local) = self.try_as_local(value, location) {
place_ref = PlaceRef { local: new_local, projection: &[] };
}