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add some comments and debug! calls to "obligation forest"

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This commit is contained in:
Niko Matsakis 2017-04-11 17:11:22 -04:00
parent 761808ef40
commit 59babd80bd
1 changed files with 35 additions and 18 deletions
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53
src/librustc_data_structures/obligation_forest/mod.rs
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@ -43,7 +43,16 @@ pub trait ObligationProcessor {
obligation: &mut Self::Obligation)
-> Result<Option<Vec<Self::Obligation>>, Self::Error>;
fn process_backedge<'c, I>(&mut self, cycle: I,
/// As we do the cycle check, we invoke this callback when we
/// encounter an actual cycle. `cycle` is an iterator that starts
/// at the start of the cycle in the stack and walks **toward the
/// top**.
///
/// In other words, if we had O1 which required O2 which required
/// O3 which required O1, we would give an iterator yielding O1,
/// O2, O3 (O1 is not yielded twice).
fn process_backedge<'c, I>(&mut self,
cycle: I,
_marker: PhantomData<&'c Self::Obligation>)
where I: Clone + Iterator<Item=&'c Self::Obligation>;
}
@ -239,8 +248,8 @@ impl<O: ForestObligation> ObligationForest<O> {
}
}
Entry::Vacant(v) => {
debug!("register_obligation_at({:?}, {:?}) - ok",
obligation, parent);
debug!("register_obligation_at({:?}, {:?}) - ok, new index is {}",
obligation, parent, self.nodes.len());
v.insert(NodeIndex::new(self.nodes.len()));
self.cache_list.push(obligation.as_predicate().clone());
self.nodes.push(Node::new(parent, obligation));
@ -376,6 +385,9 @@ impl<O: ForestObligation> ObligationForest<O> {
where P: ObligationProcessor<Obligation=O>
{
let mut stack = self.scratch.take().unwrap();
debug_assert!(stack.is_empty());
debug!("process_cycles()");
for index in 0..self.nodes.len() {
// For rustc-benchmarks/inflate-0.1.0 this state test is extremely
@ -389,6 +401,9 @@ impl<O: ForestObligation> ObligationForest<O> {
}
}
debug!("process_cycles: complete");
debug_assert!(stack.is_empty());
self.scratch = Some(stack);
}
@ -402,21 +417,6 @@ impl<O: ForestObligation> ObligationForest<O> {
NodeState::OnDfsStack => {
let index =
stack.iter().rposition(|n| *n == index).unwrap();
// I need a Clone closure
#[derive(Clone)]
struct GetObligation<'a, O: 'a>(&'a [Node<O>]);
impl<'a, 'b, O> FnOnce<(&'b usize,)> for GetObligation<'a, O> {
type Output = &'a O;
extern "rust-call" fn call_once(self, args: (&'b usize,)) -> &'a O {
&self.0[*args.0].obligation
}
}
impl<'a, 'b, O> FnMut<(&'b usize,)> for GetObligation<'a, O> {
extern "rust-call" fn call_mut(&mut self, args: (&'b usize,)) -> &'a O {
&self.0[*args.0].obligation
}
}
processor.process_backedge(stack[index..].iter().map(GetObligation(&self.nodes)),
PhantomData);
}
@ -645,3 +645,20 @@ impl<O> Node<O> {
}
}
}
// I need a Clone closure
#[derive(Clone)]
struct GetObligation<'a, O: 'a>(&'a [Node<O>]);
impl<'a, 'b, O> FnOnce<(&'b usize,)> for GetObligation<'a, O> {
type Output = &'a O;
extern "rust-call" fn call_once(self, args: (&'b usize,)) -> &'a O {
&self.0[*args.0].obligation
}
}
impl<'a, 'b, O> FnMut<(&'b usize,)> for GetObligation<'a, O> {
extern "rust-call" fn call_mut(&mut self, args: (&'b usize,)) -> &'a O {
&self.0[*args.0].obligation
}
}