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