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;
14 use mir::{Mir, BasicBlock};
16 use rustc_serialize as serialize;
18 #[derive(Clone, Debug)]
20 predecessors: RefCell<Option<IndexVec<BasicBlock, Vec<BasicBlock>>>>
24 impl serialize::Encodable for Cache {
25 fn encode<S: serialize::Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
26 serialize::Encodable::encode(&(), s)
30 impl serialize::Decodable for Cache {
31 fn decode<D: serialize::Decoder>(d: &mut D) -> Result<Self, D::Error> {
32 serialize::Decodable::decode(d).map(|_v: ()| Self::new())
38 pub fn new() -> Self {
40 predecessors: RefCell::new(None)
44 pub fn invalidate(&self) {
45 // FIXME: consider being more fine-grained
46 *self.predecessors.borrow_mut() = None;
49 pub fn predecessors(&self, mir: &Mir) -> Ref<IndexVec<BasicBlock, Vec<BasicBlock>>> {
50 if self.predecessors.borrow().is_none() {
51 *self.predecessors.borrow_mut() = Some(calculate_predecessors(mir));
54 Ref::map(self.predecessors.borrow(), |p| p.as_ref().unwrap())
58 fn calculate_predecessors(mir: &Mir) -> IndexVec<BasicBlock, Vec<BasicBlock>> {
59 let mut result = IndexVec::from_elem(vec![], mir.basic_blocks());
60 for (bb, data) in mir.basic_blocks().iter_enumerated() {
61 if let Some(ref term) = data.terminator {
62 for &tgt in term.successors().iter() {