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- moved work from `find_local` to `gather_statement` - created custom iterator for `iter_projections` - reverted change from `IndexVec` to `FxIndexMap`
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,36 +1,100 @@ | ||
| use rustc_data_structures::fx::FxHashMap; | ||
| use rustc_middle::mir::*; | ||
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| use std::iter::once; | ||
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| /// Used for reverting changes made by `DerefSeparator` | ||
| #[derive(Default, Debug)] | ||
| pub struct UnDerefer<'tcx> { | ||
| deref_chains: FxHashMap<Local, Vec<Place<'tcx>>>, | ||
| deref_chains: FxHashMap<Local, Vec<PlaceRef<'tcx>>>, | ||
| } | ||
|
|
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| impl<'tcx> UnDerefer<'tcx> { | ||
| pub fn insert(&mut self, local: Local, reffed: Place<'tcx>) { | ||
| #[inline] | ||
| pub fn insert(&mut self, local: Local, reffed: PlaceRef<'tcx>) { | ||
| let mut chain = self.deref_chains.remove(&reffed.local).unwrap_or_default(); | ||
| chain.push(reffed); | ||
| self.deref_chains.insert(local, chain); | ||
| } | ||
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| /// Returns the chain of places behind `DerefTemp` locals | ||
| pub fn deref_chain(&self, local: Local) -> &[Place<'tcx>] { | ||
| #[inline] | ||
| pub fn deref_chain(&self, local: Local) -> &[PlaceRef<'tcx>] { | ||
| self.deref_chains.get(&local).map(Vec::as_slice).unwrap_or_default() | ||
| } | ||
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| /// Iterates over the projections of a place and its deref chain. | ||
| /// | ||
| /// See [`PlaceRef::iter_projections`] | ||
| #[inline] | ||
| pub fn iter_projections( | ||
| &self, | ||
| place: PlaceRef<'tcx>, | ||
| ) -> impl Iterator<Item = (PlaceRef<'tcx>, PlaceElem<'tcx>)> + DoubleEndedIterator + '_ { | ||
| let deref_chain = self.deref_chain(place.local); | ||
|
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| deref_chain | ||
| .iter() | ||
| .map(Place::as_ref) | ||
| .chain(once(place)) | ||
| .flat_map(|place| place.iter_projections()) | ||
| ) -> impl Iterator<Item = (PlaceRef<'tcx>, PlaceElem<'tcx>)> + '_ { | ||
| ProjectionIter::new(self.deref_chain(place.local), place) | ||
| } | ||
| } | ||
|
|
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| /// The iterator returned by [`UnDerefer::iter_projections`]. | ||
| struct ProjectionIter<'a, 'tcx> { | ||
| places: SlicePlusOne<'a, PlaceRef<'tcx>>, | ||
| proj_idx: usize, | ||
| } | ||
|
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| impl<'a, 'tcx> ProjectionIter<'a, 'tcx> { | ||
| #[inline] | ||
| fn new(deref_chain: &'a [PlaceRef<'tcx>], place: PlaceRef<'tcx>) -> Self { | ||
| // just return an empty iterator for a bare local | ||
| let last = if place.as_local().is_none() { | ||
| Some(place) | ||
| } else { | ||
| debug_assert!(deref_chain.is_empty()); | ||
| None | ||
| }; | ||
|
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| ProjectionIter { places: SlicePlusOne { slice: deref_chain, last }, proj_idx: 0 } | ||
| } | ||
| } | ||
|
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| impl<'tcx> Iterator for ProjectionIter<'_, 'tcx> { | ||
| type Item = (PlaceRef<'tcx>, PlaceElem<'tcx>); | ||
|
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| #[inline] | ||
| fn next(&mut self) -> Option<(PlaceRef<'tcx>, PlaceElem<'tcx>)> { | ||
| let place = self.places.read()?; | ||
|
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| // the projection should never be empty except for a bare local which is handled in new | ||
| let partial_place = | ||
| PlaceRef { local: place.local, projection: &place.projection[..self.proj_idx] }; | ||
| let elem = place.projection[self.proj_idx]; | ||
|
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| if self.proj_idx == place.projection.len() - 1 { | ||
| self.proj_idx = 0; | ||
| self.places.advance(); | ||
| } else { | ||
| self.proj_idx += 1; | ||
| } | ||
|
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| Some((partial_place, elem)) | ||
| } | ||
| } | ||
|
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| struct SlicePlusOne<'a, T> { | ||
| slice: &'a [T], | ||
| last: Option<T>, | ||
| } | ||
|
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| impl<T: Copy> SlicePlusOne<'_, T> { | ||
| #[inline] | ||
| fn read(&self) -> Option<T> { | ||
| self.slice.first().copied().or(self.last) | ||
| } | ||
|
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| #[inline] | ||
| fn advance(&mut self) { | ||
| match self.slice { | ||
| [_, ref remainder @ ..] => { | ||
| self.slice = remainder; | ||
| } | ||
| [] => self.last = None, | ||
| } | ||
| } | ||
| } |