| //! Lazily compute the inverse of each `SwitchInt`'s switch targets. Modeled after |
| //! `Predecessors`/`PredecessorCache`. |
| |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; |
| use rustc_data_structures::sync::OnceCell; |
| use rustc_index::vec::IndexVec; |
| use rustc_serialize::{Decodable, Decoder, Encodable, Encoder}; |
| use smallvec::SmallVec; |
| |
| use crate::mir::{BasicBlock, BasicBlockData, Terminator, TerminatorKind}; |
| |
| pub type SwitchSources = FxHashMap<(BasicBlock, BasicBlock), SmallVec<[Option<u128>; 1]>>; |
| |
| #[derive(Clone, Debug)] |
| pub(super) struct SwitchSourceCache { |
| cache: OnceCell<SwitchSources>, |
| } |
| |
| impl SwitchSourceCache { |
| #[inline] |
| pub(super) fn new() -> Self { |
| SwitchSourceCache { cache: OnceCell::new() } |
| } |
| |
| /// Invalidates the switch source cache. |
| #[inline] |
| pub(super) fn invalidate(&mut self) { |
| self.cache = OnceCell::new(); |
| } |
| |
| /// Returns the switch sources for this MIR. |
| #[inline] |
| pub(super) fn compute( |
| &self, |
| basic_blocks: &IndexVec<BasicBlock, BasicBlockData<'_>>, |
| ) -> &SwitchSources { |
| self.cache.get_or_init(|| { |
| let mut switch_sources: SwitchSources = FxHashMap::default(); |
| for (bb, data) in basic_blocks.iter_enumerated() { |
| if let Some(Terminator { |
| kind: TerminatorKind::SwitchInt { targets, .. }, .. |
| }) = &data.terminator |
| { |
| for (value, target) in targets.iter() { |
| switch_sources.entry((target, bb)).or_default().push(Some(value)); |
| } |
| switch_sources.entry((targets.otherwise(), bb)).or_default().push(None); |
| } |
| } |
| |
| switch_sources |
| }) |
| } |
| } |
| |
| impl<S: Encoder> Encodable<S> for SwitchSourceCache { |
| #[inline] |
| fn encode(&self, _s: &mut S) {} |
| } |
| |
| impl<D: Decoder> Decodable<D> for SwitchSourceCache { |
| #[inline] |
| fn decode(_: &mut D) -> Self { |
| Self::new() |
| } |
| } |
| |
| impl<CTX> HashStable<CTX> for SwitchSourceCache { |
| #[inline] |
| fn hash_stable(&self, _: &mut CTX, _: &mut StableHasher) { |
| // do nothing |
| } |
| } |
| |
| TrivialTypeTraversalAndLiftImpls! { |
| SwitchSourceCache, |
| } |