| use rustc_data_structures::indexed_vec::IndexVec; |
| use rustc_data_structures::sync::{RwLock, MappedReadGuard, ReadGuard}; |
| use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableHasherResult}; |
| use rustc_serialize::{Encodable, Encoder, Decodable, Decoder}; |
| use crate::ich::StableHashingContext; |
| use crate::mir::{Body, BasicBlock}; |
| |
| #[derive(Clone, Debug)] |
| pub struct Cache { |
| predecessors: RwLock<Option<IndexVec<BasicBlock, Vec<BasicBlock>>>> |
| } |
| |
| |
| impl rustc_serialize::Encodable for Cache { |
| fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> { |
| Encodable::encode(&(), s) |
| } |
| } |
| |
| impl rustc_serialize::Decodable for Cache { |
| fn decode<D: Decoder>(d: &mut D) -> Result<Self, D::Error> { |
| Decodable::decode(d).map(|_v: ()| Self::new()) |
| } |
| } |
| |
| impl<'a> HashStable<StableHashingContext<'a>> for Cache { |
| fn hash_stable<W: StableHasherResult>(&self, |
| _: &mut StableHashingContext<'a>, |
| _: &mut StableHasher<W>) { |
| // Do nothing. |
| } |
| } |
| |
| impl Cache { |
| pub fn new() -> Self { |
| Cache { |
| predecessors: RwLock::new(None) |
| } |
| } |
| |
| pub fn invalidate(&self) { |
| // FIXME: consider being more fine-grained |
| *self.predecessors.borrow_mut() = None; |
| } |
| |
| pub fn predecessors( |
| &self, |
| body: &Body<'_> |
| ) -> MappedReadGuard<'_, IndexVec<BasicBlock, Vec<BasicBlock>>> { |
| if self.predecessors.borrow().is_none() { |
| *self.predecessors.borrow_mut() = Some(calculate_predecessors(body)); |
| } |
| |
| ReadGuard::map(self.predecessors.borrow(), |p| p.as_ref().unwrap()) |
| } |
| } |
| |
| fn calculate_predecessors(body: &Body<'_>) -> IndexVec<BasicBlock, Vec<BasicBlock>> { |
| let mut result = IndexVec::from_elem(vec![], body.basic_blocks()); |
| for (bb, data) in body.basic_blocks().iter_enumerated() { |
| if let Some(ref term) = data.terminator { |
| for &tgt in term.successors() { |
| result[tgt].push(bb); |
| } |
| } |
| } |
| |
| result |
| } |
| |
| CloneTypeFoldableAndLiftImpls! { |
| Cache, |
| } |