rustc_middle/mir/
basic_blocks.rsuse rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::graph;
use rustc_data_structures::graph::dominators::{Dominators, dominators};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::sync::OnceLock;
use rustc_index::{IndexSlice, IndexVec};
use rustc_macros::{HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
use smallvec::SmallVec;
use crate::mir::traversal::Postorder;
use crate::mir::{BasicBlock, BasicBlockData, START_BLOCK, Terminator, TerminatorKind};
#[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable, TypeVisitable)]
pub struct BasicBlocks<'tcx> {
basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
cache: Cache,
}
type Predecessors = IndexVec<BasicBlock, SmallVec<[BasicBlock; 4]>>;
type SwitchSources = FxHashMap<(BasicBlock, BasicBlock), SmallVec<[Option<u128>; 1]>>;
#[derive(Clone, Default, Debug)]
struct Cache {
predecessors: OnceLock<Predecessors>,
switch_sources: OnceLock<SwitchSources>,
reverse_postorder: OnceLock<Vec<BasicBlock>>,
dominators: OnceLock<Dominators<BasicBlock>>,
}
impl<'tcx> BasicBlocks<'tcx> {
#[inline]
pub fn new(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>) -> Self {
BasicBlocks { basic_blocks, cache: Cache::default() }
}
pub fn dominators(&self) -> &Dominators<BasicBlock> {
self.cache.dominators.get_or_init(|| dominators(self))
}
#[inline]
pub fn predecessors(&self) -> &Predecessors {
self.cache.predecessors.get_or_init(|| {
let mut preds = IndexVec::from_elem(SmallVec::new(), &self.basic_blocks);
for (bb, data) in self.basic_blocks.iter_enumerated() {
if let Some(term) = &data.terminator {
for succ in term.successors() {
preds[succ].push(bb);
}
}
}
preds
})
}
#[inline]
pub fn reverse_postorder(&self) -> &[BasicBlock] {
self.cache.reverse_postorder.get_or_init(|| {
let mut rpo: Vec<_> = Postorder::new(&self.basic_blocks, START_BLOCK, ()).collect();
rpo.reverse();
rpo
})
}
#[inline]
pub fn switch_sources(&self) -> &SwitchSources {
self.cache.switch_sources.get_or_init(|| {
let mut switch_sources: SwitchSources = FxHashMap::default();
for (bb, data) in self.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
})
}
#[inline]
pub fn as_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
self.invalidate_cfg_cache();
&mut self.basic_blocks
}
#[inline]
pub fn as_mut_preserves_cfg(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
&mut self.basic_blocks
}
pub fn invalidate_cfg_cache(&mut self) {
self.cache = Cache::default();
}
}
impl<'tcx> std::ops::Deref for BasicBlocks<'tcx> {
type Target = IndexSlice<BasicBlock, BasicBlockData<'tcx>>;
#[inline]
fn deref(&self) -> &IndexSlice<BasicBlock, BasicBlockData<'tcx>> {
&self.basic_blocks
}
}
impl<'tcx> graph::DirectedGraph for BasicBlocks<'tcx> {
type Node = BasicBlock;
#[inline]
fn num_nodes(&self) -> usize {
self.basic_blocks.len()
}
}
impl<'tcx> graph::StartNode for BasicBlocks<'tcx> {
#[inline]
fn start_node(&self) -> Self::Node {
START_BLOCK
}
}
impl<'tcx> graph::Successors for BasicBlocks<'tcx> {
#[inline]
fn successors(&self, node: Self::Node) -> impl Iterator<Item = Self::Node> {
self.basic_blocks[node].terminator().successors()
}
}
impl<'tcx> graph::Predecessors for BasicBlocks<'tcx> {
#[inline]
fn predecessors(&self, node: Self::Node) -> impl Iterator<Item = Self::Node> {
self.predecessors()[node].iter().copied()
}
}
TrivialTypeTraversalImpls! { Cache }
impl<S: Encoder> Encodable<S> for Cache {
#[inline]
fn encode(&self, _s: &mut S) {}
}
impl<D: Decoder> Decodable<D> for Cache {
#[inline]
fn decode(_: &mut D) -> Self {
Default::default()
}
}
impl<CTX> HashStable<CTX> for Cache {
#[inline]
fn hash_stable(&self, _: &mut CTX, _: &mut StableHasher) {}
}