1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use std::cell::{Ref, RefCell};
12 use rustc_data_structures::indexed_vec::IndexVec;
13 use rustc_data_structures::stable_hasher::{HashStable, StableHasher,
15 use ich::StableHashingContext;
16 use mir::{Mir, BasicBlock};
18 use rustc_serialize as serialize;
20 #[derive(Clone, Debug)]
22 predecessors: RefCell<Option<IndexVec<BasicBlock, Vec<BasicBlock>>>>
26 impl serialize::Encodable for Cache {
27 fn encode<S: serialize::Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
28 serialize::Encodable::encode(&(), s)
32 impl serialize::Decodable for Cache {
33 fn decode<D: serialize::Decoder>(d: &mut D) -> Result<Self, D::Error> {
34 serialize::Decodable::decode(d).map(|_v: ()| Self::new())
38 impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for Cache {
39 fn hash_stable<W: StableHasherResult>(&self,
40 _: &mut StableHashingContext<'a, 'tcx>,
41 _: &mut StableHasher<W>) {
47 pub fn new() -> Self {
49 predecessors: RefCell::new(None)
53 pub fn invalidate(&self) {
54 // FIXME: consider being more fine-grained
55 *self.predecessors.borrow_mut() = None;
58 pub fn predecessors(&self, mir: &Mir) -> Ref<IndexVec<BasicBlock, Vec<BasicBlock>>> {
59 if self.predecessors.borrow().is_none() {
60 *self.predecessors.borrow_mut() = Some(calculate_predecessors(mir));
63 Ref::map(self.predecessors.borrow(), |p| p.as_ref().unwrap())
67 fn calculate_predecessors(mir: &Mir) -> IndexVec<BasicBlock, Vec<BasicBlock>> {
68 let mut result = IndexVec::from_elem(vec![], mir.basic_blocks());
69 for (bb, data) in mir.basic_blocks().iter_enumerated() {
70 if let Some(ref term) = data.terminator {
71 for &tgt in term.successors().iter() {