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Auto merge of #31349 - nikomatsakis:issue-31157-obligation-forest-cache, r=aturon

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Have the `ObligationForest` keep some per-tree state (or type `T`) and have it give a mutable reference for use when processing obligations. In this case, it will be a hashmap. This obviously affects the work that @soltanmm has been doing on snapshotting. I partly want to toss this out there for discussion.

Fixes #31157. (The test in question goes to approx. 30s instead of 5 minutes for me.)
cc #30977.
cc @aturon @arielb1 @soltanmm

r? @aturon who reviewed original `ObligationForest`
This commit is contained in:
bors 2016-02-05 17:16:03 +00:00
commit 6dc112dbb7
5 changed files with 313 additions and 151 deletions
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179
src/librustc/middle/traits/fulfill.rs
View file

@ -36,6 +36,7 @@ pub struct GlobalFulfilledPredicates<'tcx> {
dep_graph: DepGraph, dep_graph: DepGraph,
} }
#[derive(Debug)]
pub struct LocalFulfilledPredicates<'tcx> { pub struct LocalFulfilledPredicates<'tcx> {
set: FnvHashSet<ty::Predicate<'tcx>> set: FnvHashSet<ty::Predicate<'tcx>>
} }
@ -66,7 +67,8 @@ pub struct FulfillmentContext<'tcx> {
// A list of all obligations that have been registered with this // A list of all obligations that have been registered with this
// fulfillment context. // fulfillment context.
predicates: ObligationForest<PendingPredicateObligation<'tcx>>, predicates: ObligationForest<PendingPredicateObligation<'tcx>,
LocalFulfilledPredicates<'tcx>>,
// A set of constraints that regionck must validate. Each // A set of constraints that regionck must validate. Each
// constraint has the form `T:'a`, meaning "some type `T` must // constraint has the form `T:'a`, meaning "some type `T` must
@ -192,7 +194,7 @@ impl<'tcx> FulfillmentContext<'tcx> {
obligation: obligation, obligation: obligation,
stalled_on: vec![] stalled_on: vec![]
}; };
self.predicates.push_root(obligation); self.predicates.push_tree(obligation, LocalFulfilledPredicates::new());
} }
pub fn region_obligations(&self, pub fn region_obligations(&self,
@ -278,10 +280,11 @@ impl<'tcx> FulfillmentContext<'tcx> {
let outcome = { let outcome = {
let region_obligations = &mut self.region_obligations; let region_obligations = &mut self.region_obligations;
self.predicates.process_obligations( self.predicates.process_obligations(
|obligation, backtrace| process_predicate(selcx, |obligation, tree, backtrace| process_predicate(selcx,
obligation, tree,
backtrace, obligation,
region_obligations)) backtrace,
region_obligations))
}; };
debug!("select_where_possible: outcome={:?}", outcome); debug!("select_where_possible: outcome={:?}", outcome);
@ -315,61 +318,97 @@ impl<'tcx> FulfillmentContext<'tcx> {
/// Like `process_predicate1`, but wrap result into a pending predicate. /// Like `process_predicate1`, but wrap result into a pending predicate.
fn process_predicate<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>, fn process_predicate<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
tree_cache: &mut LocalFulfilledPredicates<'tcx>,
pending_obligation: &mut PendingPredicateObligation<'tcx>, pending_obligation: &mut PendingPredicateObligation<'tcx>,
backtrace: Backtrace<PendingPredicateObligation<'tcx>>, mut backtrace: Backtrace<PendingPredicateObligation<'tcx>>,
region_obligations: &mut NodeMap<Vec<RegionObligation<'tcx>>>) region_obligations: &mut NodeMap<Vec<RegionObligation<'tcx>>>)
-> Result<Option<Vec<PendingPredicateObligation<'tcx>>>, -> Result<Option<Vec<PendingPredicateObligation<'tcx>>>,
FulfillmentErrorCode<'tcx>> FulfillmentErrorCode<'tcx>>
{ {
match process_predicate1(selcx, pending_obligation, backtrace, region_obligations) { match process_predicate1(selcx, pending_obligation, backtrace.clone(), region_obligations) {
Ok(Some(v)) => { Ok(Some(v)) => {
// FIXME(#30977) the right thing to do here, I think, is to permit // FIXME(#30977) The code below is designed to detect (and
// DAGs. That is, we should detect whenever this predicate // permit) DAGs, while still ensuring that the reasoning
// has appeared somewhere in the current tree./ If it's a // is acyclic. However, it does a few things
// parent, that's a cycle, and we should either error out // suboptimally. For example, it refreshes type variables
// or consider it ok. But if it's NOT a parent, we can // a lot, probably more than needed, but also less than
// ignore it, since it will be proven (or not) separately. // you might want.
// However, this is a touch tricky, so I'm doing something //
// a bit hackier for now so that the `huge-struct.rs` passes. // - more than needed: I want to be very sure we don't
// accidentally treat a cycle as a DAG, so I am
// refreshing type variables as we walk the ancestors;
// but we are going to repeat this a lot, which is
// sort of silly, and it would be nicer to refresh
// them *in place* so that later predicate processing
// can benefit from the same work;
// - less than you might want: we only add items in the cache here,
// but maybe we learn more about type variables and could add them into
// the cache later on.
let tcx = selcx.tcx(); let tcx = selcx.tcx();
let retain_vec: Vec<_> = { // Compute a little FnvHashSet for the ancestors. We only
let mut dedup = FnvHashSet(); // do this the first time that we care.
v.iter() let mut cache = None;
.map(|o| { let mut is_ancestor = |predicate: &ty::Predicate<'tcx>| {
if cache.is_none() {
let mut c = FnvHashSet();
for ancestor in backtrace.by_ref() {
// Ugh. This just feels ridiculously
// inefficient. But we need to compare
// predicates without being concerned about
// the vagaries of type inference, so for now
// just ensure that they are always
// up-to-date. (I suppose we could just use a
// snapshot and check if they are unifiable?)
let resolved_predicate =
selcx.infcx().resolve_type_vars_if_possible(
&ancestor.obligation.predicate);
c.insert(resolved_predicate);
}
cache = Some(c);
}
cache.as_ref().unwrap().contains(predicate)
};
let pending_predicate_obligations: Vec<_> =
v.into_iter()
.filter_map(|obligation| {
// Probably silly, but remove any inference
// variables. This is actually crucial to the
// ancestor check below, but it's not clear that
// it makes sense to ALWAYS do it.
let obligation = selcx.infcx().resolve_type_vars_if_possible(&obligation);
// Screen out obligations that we know globally // Screen out obligations that we know globally
// are true. This should really be the DAG check // are true. This should really be the DAG check
// mentioned above. // mentioned above.
if tcx.fulfilled_predicates.borrow().check_duplicate(&o.predicate) { if tcx.fulfilled_predicates.borrow().check_duplicate(&obligation.predicate) {
return false; return None;
} }
// If we see two siblings that are exactly the // Check whether this obligation appears somewhere else in the tree.
// same, no need to add them twice. if tree_cache.is_duplicate_or_add(&obligation.predicate) {
if !dedup.insert(&o.predicate) { // If the obligation appears as a parent,
return false; // allow it, because that is a cycle.
// Otherwise though we can just ignore
// it. Note that we have to be careful around
// inference variables here -- for the
// purposes of the ancestor check, we retain
// the invariant that all type variables are
// fully refreshed.
if !(&mut is_ancestor)(&obligation.predicate) {
return None;
}
} }
true Some(PendingPredicateObligation {
obligation: obligation,
stalled_on: vec![]
})
}) })
.collect() .collect();
};
let pending_predicate_obligations =
v.into_iter()
.zip(retain_vec)
.flat_map(|(o, retain)| {
if retain {
Some(PendingPredicateObligation {
obligation: o,
stalled_on: vec![]
})
} else {
None
}
})
.collect();
Ok(Some(pending_predicate_obligations)) Ok(Some(pending_predicate_obligations))
} }
@ -405,7 +444,7 @@ fn process_predicate1<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
pending_obligation.stalled_on = vec![]; pending_obligation.stalled_on = vec![];
} }
let obligation = &pending_obligation.obligation; let obligation = &mut pending_obligation.obligation;
// If we exceed the recursion limit, take a moment to look for a // If we exceed the recursion limit, take a moment to look for a
// cycle so we can give a better error report from here, where we // cycle so we can give a better error report from here, where we
@ -417,8 +456,16 @@ fn process_predicate1<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
} }
} }
if obligation.predicate.has_infer_types() {
obligation.predicate = selcx.infcx().resolve_type_vars_if_possible(&obligation.predicate);
}
match obligation.predicate { match obligation.predicate {
ty::Predicate::Trait(ref data) => { ty::Predicate::Trait(ref data) => {
if selcx.tcx().fulfilled_predicates.borrow().check_duplicate_trait(data) {
return Ok(Some(vec![]));
}
if coinductive_match(selcx, obligation, data, &backtrace) { if coinductive_match(selcx, obligation, data, &backtrace) {
return Ok(Some(vec![])); return Ok(Some(vec![]));
} }
@ -426,9 +473,14 @@ fn process_predicate1<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
let trait_obligation = obligation.with(data.clone()); let trait_obligation = obligation.with(data.clone());
match selcx.select(&trait_obligation) { match selcx.select(&trait_obligation) {
Ok(Some(vtable)) => { Ok(Some(vtable)) => {
info!("selecting trait `{:?}` at depth {} yielded Ok(Some)",
data, obligation.recursion_depth);
Ok(Some(vtable.nested_obligations())) Ok(Some(vtable.nested_obligations()))
} }
Ok(None) => { Ok(None) => {
info!("selecting trait `{:?}` at depth {} yielded Ok(None)",
data, obligation.recursion_depth);
// This is a bit subtle: for the most part, the // This is a bit subtle: for the most part, the
// only reason we can fail to make progress on // only reason we can fail to make progress on
// trait selection is because we don't have enough // trait selection is because we don't have enough
@ -457,6 +509,8 @@ fn process_predicate1<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
Ok(None) Ok(None)
} }
Err(selection_err) => { Err(selection_err) => {
info!("selecting trait `{:?}` at depth {} yielded Err",
data, obligation.recursion_depth);
Err(CodeSelectionError(selection_err)) Err(CodeSelectionError(selection_err))
} }
} }
@ -642,18 +696,28 @@ impl<'tcx> GlobalFulfilledPredicates<'tcx> {
pub fn check_duplicate(&self, key: &ty::Predicate<'tcx>) -> bool { pub fn check_duplicate(&self, key: &ty::Predicate<'tcx>) -> bool {
if let ty::Predicate::Trait(ref data) = *key { if let ty::Predicate::Trait(ref data) = *key {
// For the global predicate registry, when we find a match, it self.check_duplicate_trait(data)
// may have been computed by some other task, so we want to } else {
// add a read from the node corresponding to the predicate false
// processing to make sure we get the transitive dependencies.
if self.set.contains(data) {
debug_assert!(data.is_global());
self.dep_graph.read(data.dep_node());
return true;
}
} }
}
return false; pub fn check_duplicate_trait(&self, data: &ty::PolyTraitPredicate<'tcx>) -> bool {
// For the global predicate registry, when we find a match, it
// may have been computed by some other task, so we want to
// add a read from the node corresponding to the predicate
// processing to make sure we get the transitive dependencies.
if self.set.contains(data) {
debug_assert!(data.is_global());
self.dep_graph.read(data.dep_node());
debug!("check_duplicate: global predicate `{:?}` already proved elsewhere", data);
info!("check_duplicate_trait hit: `{:?}`", data);
true
} else {
false
}
} }
fn add_if_global(&mut self, key: &ty::Predicate<'tcx>) { fn add_if_global(&mut self, key: &ty::Predicate<'tcx>) {
@ -663,7 +727,10 @@ impl<'tcx> GlobalFulfilledPredicates<'tcx> {
// already has the required read edges, so we don't need // already has the required read edges, so we don't need
// to add any more edges here. // to add any more edges here.
if data.is_global() { if data.is_global() {
self.set.insert(data.clone()); if self.set.insert(data.clone()) {
debug!("add_if_global: global predicate `{:?}` added", data);
info!("check_duplicate_trait entry: `{:?}`", data);
}
} }
} }
} }

15
src/librustc_data_structures/obligation_forest/README.md
View file

@ -9,15 +9,18 @@ place).
`ObligationForest` supports two main public operations (there are a `ObligationForest` supports two main public operations (there are a
few others not discussed here): few others not discussed here):
1. Add a new root obligation (`push_root`). 1. Add a new root obligations (`push_tree`).
2. Process the pending obligations (`process_obligations`). 2. Process the pending obligations (`process_obligations`).
When a new obligation `N` is added, it becomes the root of an When a new obligation `N` is added, it becomes the root of an
obligation tree. This tree is a singleton to start, so `N` is both the obligation tree. This tree can also carry some per-tree state `T`,
root and the only leaf. Each time the `process_obligations` method is which is given at the same time. This tree is a singleton to start, so
called, it will invoke its callback with every pending obligation (so `N` is both the root and the only leaf. Each time the
that will include `N`, the first time). The callback shoud process the `process_obligations` method is called, it will invoke its callback
obligation `O` that it is given and return one of three results: with every pending obligation (so that will include `N`, the first
time). The callback also receives a (mutable) reference to the
per-tree state `T`. The callback should process the obligation `O`
that it is given and return one of three results:
- `Ok(None)` -> ambiguous result. Obligation was neither a success - `Ok(None)` -> ambiguous result. Obligation was neither a success
nor a failure. It is assumed that further attempts to process the nor a failure. It is assumed that further attempts to process the

145
src/librustc_data_structures/obligation_forest/mod.rs
View file

@ -19,11 +19,16 @@ use std::fmt::Debug;
use std::mem; use std::mem;
mod node_index; mod node_index;
use self::node_index::NodeIndex;
mod tree_index;
use self::tree_index::TreeIndex;
#[cfg(test)] #[cfg(test)]
mod test; mod test;
pub struct ObligationForest<O> { pub struct ObligationForest<O,T> {
/// The list of obligations. In between calls to /// The list of obligations. In between calls to
/// `process_obligations`, this list only contains nodes in the /// `process_obligations`, this list only contains nodes in the
/// `Pending` or `Success` state (with a non-zero number of /// `Pending` or `Success` state (with a non-zero number of
@ -37,6 +42,7 @@ pub struct ObligationForest<O> {
/// at a higher index than its parent. This is needed by the /// at a higher index than its parent. This is needed by the
/// backtrace iterator (which uses `split_at`). /// backtrace iterator (which uses `split_at`).
nodes: Vec<Node<O>>, nodes: Vec<Node<O>>,
trees: Vec<Tree<T>>,
snapshots: Vec<usize> snapshots: Vec<usize>
} }
@ -44,12 +50,15 @@ pub struct Snapshot {
len: usize, len: usize,
} }
pub use self::node_index::NodeIndex; struct Tree<T> {
root: NodeIndex,
state: T,
}
struct Node<O> { struct Node<O> {
state: NodeState<O>, state: NodeState<O>,
parent: Option<NodeIndex>, parent: Option<NodeIndex>,
root: NodeIndex, // points to the root, which may be the current node tree: TreeIndex,
} }
/// The state of one node in some tree within the forest. This /// The state of one node in some tree within the forest. This
@ -99,9 +108,10 @@ pub struct Error<O,E> {
pub backtrace: Vec<O>, pub backtrace: Vec<O>,
} }
impl<O: Debug> ObligationForest<O> { impl<O: Debug, T: Debug> ObligationForest<O, T> {
pub fn new() -> ObligationForest<O> { pub fn new() -> ObligationForest<O, T> {
ObligationForest { ObligationForest {
trees: vec![],
nodes: vec![], nodes: vec![],
snapshots: vec![] snapshots: vec![]
} }
@ -114,30 +124,39 @@ impl<O: Debug> ObligationForest<O> {
} }
pub fn start_snapshot(&mut self) -> Snapshot { pub fn start_snapshot(&mut self) -> Snapshot {
self.snapshots.push(self.nodes.len()); self.snapshots.push(self.trees.len());
Snapshot { len: self.snapshots.len() } Snapshot { len: self.snapshots.len() }
} }
pub fn commit_snapshot(&mut self, snapshot: Snapshot) { pub fn commit_snapshot(&mut self, snapshot: Snapshot) {
assert_eq!(snapshot.len, self.snapshots.len()); assert_eq!(snapshot.len, self.snapshots.len());
let nodes_len = self.snapshots.pop().unwrap(); let trees_len = self.snapshots.pop().unwrap();
assert!(self.nodes.len() >= nodes_len); assert!(self.trees.len() >= trees_len);
} }
pub fn rollback_snapshot(&mut self, snapshot: Snapshot) { pub fn rollback_snapshot(&mut self, snapshot: Snapshot) {
// Check that we are obeying stack discipline. // Check that we are obeying stack discipline.
assert_eq!(snapshot.len, self.snapshots.len()); assert_eq!(snapshot.len, self.snapshots.len());
let nodes_len = self.snapshots.pop().unwrap(); let trees_len = self.snapshots.pop().unwrap();
// The only action permitted while in a snapshot is to push // If nothing happened in snapshot, done.
// new root obligations. Because no processing will have been if self.trees.len() == trees_len {
// done, those roots should still be in the pending state. return;
debug_assert!(self.nodes[nodes_len..].iter().all(|n| match n.state { }
NodeState::Pending { .. } => true,
_ => false,
}));
self.nodes.truncate(nodes_len); // Find root of first tree; because nothing can happen in a
// snapshot but pushing trees, all nodes after that should be
// roots of other trees as well
let first_root_index = self.trees[trees_len].root.get();
debug_assert!(
self.nodes[first_root_index..]
.iter()
.zip(first_root_index..)
.all(|(root, root_index)| self.trees[root.tree.get()].root.get() == root_index));
// Pop off tree/root pairs pushed during snapshot.
self.trees.truncate(trees_len);
self.nodes.truncate(first_root_index);
} }
pub fn in_snapshot(&self) -> bool { pub fn in_snapshot(&self) -> bool {
@ -147,9 +166,11 @@ impl<O: Debug> ObligationForest<O> {
/// Adds a new tree to the forest. /// Adds a new tree to the forest.
/// ///
/// This CAN be done during a snapshot. /// This CAN be done during a snapshot.
pub fn push_root(&mut self, obligation: O) { pub fn push_tree(&mut self, obligation: O, tree_state: T) {
let index = NodeIndex::new(self.nodes.len()); let index = NodeIndex::new(self.nodes.len());
self.nodes.push(Node::new(index, None, obligation)); let tree = TreeIndex::new(self.trees.len());
self.trees.push(Tree { root: index, state: tree_state });
self.nodes.push(Node::new(tree, None, obligation));
} }
/// Convert all remaining obligations to the given error. /// Convert all remaining obligations to the given error.
@ -186,7 +207,7 @@ impl<O: Debug> ObligationForest<O> {
/// ///
/// This CANNOT be unrolled (presently, at least). /// This CANNOT be unrolled (presently, at least).
pub fn process_obligations<E,F>(&mut self, mut action: F) -> Outcome<O,E> pub fn process_obligations<E,F>(&mut self, mut action: F) -> Outcome<O,E>
where E: Debug, F: FnMut(&mut O, Backtrace<O>) -> Result<Option<Vec<O>>, E> where E: Debug, F: FnMut(&mut O, &mut T, Backtrace<O>) -> Result<Option<Vec<O>>, E>
{ {
debug!("process_obligations(len={})", self.nodes.len()); debug!("process_obligations(len={})", self.nodes.len());
assert!(!self.in_snapshot()); // cannot unroll this action assert!(!self.in_snapshot()); // cannot unroll this action
@ -210,7 +231,7 @@ impl<O: Debug> ObligationForest<O> {
index, self.nodes[index].state); index, self.nodes[index].state);
let result = { let result = {
let parent = self.nodes[index].parent; let Node { tree, parent, .. } = self.nodes[index];
let (prefix, suffix) = self.nodes.split_at_mut(index); let (prefix, suffix) = self.nodes.split_at_mut(index);
let backtrace = Backtrace::new(prefix, parent); let backtrace = Backtrace::new(prefix, parent);
match suffix[0].state { match suffix[0].state {
@ -218,7 +239,7 @@ impl<O: Debug> ObligationForest<O> {
NodeState::Success { .. } => NodeState::Success { .. } =>
continue, continue,
NodeState::Pending { ref mut obligation } => NodeState::Pending { ref mut obligation } =>
action(obligation, backtrace), action(obligation, &mut self.trees[tree.get()].state, backtrace),
} }
}; };
@ -268,11 +289,11 @@ impl<O: Debug> ObligationForest<O> {
self.update_parent(index); self.update_parent(index);
} else { } else {
// create child work // create child work
let root_index = self.nodes[index].root; let tree_index = self.nodes[index].tree;
let node_index = NodeIndex::new(index); let node_index = NodeIndex::new(index);
self.nodes.extend( self.nodes.extend(
children.into_iter() children.into_iter()
.map(|o| Node::new(root_index, Some(node_index), o))); .map(|o| Node::new(tree_index, Some(node_index), o)));
} }
// change state from `Pending` to `Success`, temporarily swapping in `Error` // change state from `Pending` to `Success`, temporarily swapping in `Error`
@ -311,8 +332,9 @@ impl<O: Debug> ObligationForest<O> {
/// skip the remaining obligations from a tree once some other /// skip the remaining obligations from a tree once some other
/// node in the tree is found to be in error. /// node in the tree is found to be in error.
fn inherit_error(&mut self, child: usize) { fn inherit_error(&mut self, child: usize) {
let root = self.nodes[child].root.get(); let tree = self.nodes[child].tree;
if let NodeState::Error = self.nodes[root].state { let root = self.trees[tree.get()].root;
if let NodeState::Error = self.nodes[root.get()].state {
self.nodes[child].state = NodeState::Error; self.nodes[child].state = NodeState::Error;
} }
} }
@ -353,7 +375,8 @@ impl<O: Debug> ObligationForest<O> {
/// indices. Cannot be used during a transaction. /// indices. Cannot be used during a transaction.
fn compress(&mut self) -> Vec<O> { fn compress(&mut self) -> Vec<O> {
assert!(!self.in_snapshot()); // didn't write code to unroll this action assert!(!self.in_snapshot()); // didn't write code to unroll this action
let mut rewrites: Vec<_> = (0..self.nodes.len()).collect(); let mut node_rewrites: Vec<_> = (0..self.nodes.len()).collect();
let mut tree_rewrites: Vec<_> = (0..self.trees.len()).collect();
// Finish propagating error state. Note that in this case we // Finish propagating error state. Note that in this case we
// only have to check immediate parents, rather than all // only have to check immediate parents, rather than all
@ -366,43 +389,69 @@ impl<O: Debug> ObligationForest<O> {
} }
} }
// Determine which trees to remove by checking if their root
// is popped.
let mut dead_trees = 0;
let trees_len = self.trees.len();
for i in 0..trees_len {
let root_node = self.trees[i].root;
if self.nodes[root_node.get()].is_popped() {
dead_trees += 1;
} else if dead_trees > 0 {
self.trees.swap(i, i - dead_trees);
tree_rewrites[i] -= dead_trees;
}
}
// Now go through and move all nodes that are either // Now go through and move all nodes that are either
// successful or which have an error over into to the end of // successful or which have an error over into to the end of
// the list, preserving the relative order of the survivors // the list, preserving the relative order of the survivors
// (which is important for the `inherit_error` logic). // (which is important for the `inherit_error` logic).
let mut dead = 0; let mut dead_nodes = 0;
for i in 0..nodes_len { for i in 0..nodes_len {
if self.nodes[i].is_popped() { if self.nodes[i].is_popped() {
dead += 1; dead_nodes += 1;
} else if dead > 0 { } else if dead_nodes > 0 {
self.nodes.swap(i, i - dead); self.nodes.swap(i, i - dead_nodes);
rewrites[i] -= dead; node_rewrites[i] -= dead_nodes;
} }
} }
// No compression needed.
if dead_nodes == 0 && dead_trees == 0 {
return vec![];
}
// Pop off the trees we killed.
self.trees.truncate(trees_len - dead_trees);
// Pop off all the nodes we killed and extract the success // Pop off all the nodes we killed and extract the success
// stories. // stories.
let successful = let successful =
(0 .. dead).map(|_| self.nodes.pop().unwrap()) (0 .. dead_nodes)
.flat_map(|node| match node.state { .map(|_| self.nodes.pop().unwrap())
NodeState::Error => None, .flat_map(|node| match node.state {
NodeState::Pending { .. } => unreachable!(), NodeState::Error => None,
NodeState::Success { obligation, num_incomplete_children } => { NodeState::Pending { .. } => unreachable!(),
assert_eq!(num_incomplete_children, 0); NodeState::Success { obligation, num_incomplete_children } => {
Some(obligation) assert_eq!(num_incomplete_children, 0);
} Some(obligation)
}) }
.collect(); })
.collect();
// Adjust the parent indices, since we compressed things. // Adjust the various indices, since we compressed things.
for tree in &mut self.trees {
tree.root = NodeIndex::new(node_rewrites[tree.root.get()]);
}
for node in &mut self.nodes { for node in &mut self.nodes {
if let Some(ref mut index) = node.parent { if let Some(ref mut index) = node.parent {
let new_index = rewrites[index.get()]; let new_index = node_rewrites[index.get()];
debug_assert!(new_index < (nodes_len - dead)); debug_assert!(new_index < (nodes_len - dead_nodes));
*index = NodeIndex::new(new_index); *index = NodeIndex::new(new_index);
} }
node.root = NodeIndex::new(rewrites[node.root.get()]); node.tree = TreeIndex::new(tree_rewrites[node.tree.get()]);
} }
successful successful
@ -410,11 +459,11 @@ impl<O: Debug> ObligationForest<O> {
} }
impl<O> Node<O> { impl<O> Node<O> {
fn new(root: NodeIndex, parent: Option<NodeIndex>, obligation: O) -> Node<O> { fn new(tree: TreeIndex, parent: Option<NodeIndex>, obligation: O) -> Node<O> {
Node { Node {
parent: parent, parent: parent,
state: NodeState::Pending { obligation: obligation }, state: NodeState::Pending { obligation: obligation },
root: root tree: tree,
} }
} }

97
src/librustc_data_structures/obligation_forest/test.rs
View file

@ -13,22 +13,24 @@ use super::{ObligationForest, Outcome, Error};
#[test] #[test]
fn push_pop() { fn push_pop() {
let mut forest = ObligationForest::new(); let mut forest = ObligationForest::new();
forest.push_root("A"); forest.push_tree("A", "A");
forest.push_root("B"); forest.push_tree("B", "B");
forest.push_root("C"); forest.push_tree("C", "C");
// first round, B errors out, A has subtasks, and C completes, creating this: // first round, B errors out, A has subtasks, and C completes, creating this:
// A |-> A.1 // A |-> A.1
// |-> A.2 // |-> A.2
// |-> A.3 // |-> A.3
let Outcome { completed: ok, errors: err, .. } = forest.process_obligations(|obligation, _| { let Outcome { completed: ok, errors: err, .. } =
match *obligation { forest.process_obligations(|obligation, tree, _| {
"A" => Ok(Some(vec!["A.1", "A.2", "A.3"])), assert_eq!(obligation.chars().next(), tree.chars().next());
"B" => Err("B is for broken"), match *obligation {
"C" => Ok(Some(vec![])), "A" => Ok(Some(vec!["A.1", "A.2", "A.3"])),
_ => unreachable!(), "B" => Err("B is for broken"),
} "C" => Ok(Some(vec![])),
}); _ => unreachable!(),
}
});
assert_eq!(ok, vec!["C"]); assert_eq!(ok, vec!["C"]);
assert_eq!(err, vec![Error {error: "B is for broken", assert_eq!(err, vec![Error {error: "B is for broken",
backtrace: vec!["B"]}]); backtrace: vec!["B"]}]);
@ -39,9 +41,10 @@ fn push_pop() {
// |-> A.3 |-> A.3.i // |-> A.3 |-> A.3.i
// D |-> D.1 // D |-> D.1
// |-> D.2 // |-> D.2
forest.push_root("D"); forest.push_tree("D", "D");
let Outcome { completed: ok, errors: err, .. }: Outcome<&'static str, ()> = let Outcome { completed: ok, errors: err, .. }: Outcome<&'static str, ()> =
forest.process_obligations(|obligation, _| { forest.process_obligations(|obligation, tree, _| {
assert_eq!(obligation.chars().next(), tree.chars().next());
match *obligation { match *obligation {
"A.1" => Ok(None), "A.1" => Ok(None),
"A.2" => Ok(None), "A.2" => Ok(None),
@ -58,26 +61,30 @@ fn push_pop() {
// propagates to A.3.i, but not D.1 or D.2. // propagates to A.3.i, but not D.1 or D.2.
// D |-> D.1 |-> D.1.i // D |-> D.1 |-> D.1.i
// |-> D.2 |-> D.2.i // |-> D.2 |-> D.2.i
let Outcome { completed: ok, errors: err, .. } = forest.process_obligations(|obligation, _| { let Outcome { completed: ok, errors: err, .. } =
match *obligation { forest.process_obligations(|obligation, tree, _| {
"A.1" => Ok(Some(vec![])), assert_eq!(obligation.chars().next(), tree.chars().next());
"A.2" => Err("A is for apple"), match *obligation {
"D.1" => Ok(Some(vec!["D.1.i"])), "A.1" => Ok(Some(vec![])),
"D.2" => Ok(Some(vec!["D.2.i"])), "A.2" => Err("A is for apple"),
_ => unreachable!(), "D.1" => Ok(Some(vec!["D.1.i"])),
} "D.2" => Ok(Some(vec!["D.2.i"])),
}); _ => unreachable!(),
}
});
assert_eq!(ok, vec!["A.1"]); assert_eq!(ok, vec!["A.1"]);
assert_eq!(err, vec![Error { error: "A is for apple", assert_eq!(err, vec![Error { error: "A is for apple",
backtrace: vec!["A.2", "A"] }]); backtrace: vec!["A.2", "A"] }]);
// fourth round: error in D.1.i that should propagate to D.2.i // fourth round: error in D.1.i that should propagate to D.2.i
let Outcome { completed: ok, errors: err, .. } = forest.process_obligations(|obligation, _| { let Outcome { completed: ok, errors: err, .. } =
match *obligation { forest.process_obligations(|obligation, tree, _| {
"D.1.i" => Err("D is for dumb"), assert_eq!(obligation.chars().next(), tree.chars().next());
_ => panic!("unexpected obligation {:?}", obligation), match *obligation {
} "D.1.i" => Err("D is for dumb"),
}); _ => panic!("unexpected obligation {:?}", obligation),
}
});
assert_eq!(ok, Vec::<&'static str>::new()); assert_eq!(ok, Vec::<&'static str>::new());
assert_eq!(err, vec![Error { error: "D is for dumb", assert_eq!(err, vec![Error { error: "D is for dumb",
backtrace: vec!["D.1.i", "D.1", "D"] }]); backtrace: vec!["D.1.i", "D.1", "D"] }]);
@ -94,10 +101,11 @@ fn push_pop() {
#[test] #[test]
fn success_in_grandchildren() { fn success_in_grandchildren() {
let mut forest = ObligationForest::new(); let mut forest = ObligationForest::new();
forest.push_root("A"); forest.push_tree("A", "A");
let Outcome { completed: ok, errors: err, .. } = let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations::<(),_>(|obligation, _| { forest.process_obligations::<(),_>(|obligation, tree, _| {
assert_eq!(obligation.chars().next(), tree.chars().next());
match *obligation { match *obligation {
"A" => Ok(Some(vec!["A.1", "A.2", "A.3"])), "A" => Ok(Some(vec!["A.1", "A.2", "A.3"])),
_ => unreachable!(), _ => unreachable!(),
@ -107,7 +115,8 @@ fn success_in_grandchildren() {
assert!(err.is_empty()); assert!(err.is_empty());
let Outcome { completed: ok, errors: err, .. } = let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations::<(),_>(|obligation, _| { forest.process_obligations::<(),_>(|obligation, tree, _| {
assert_eq!(obligation.chars().next(), tree.chars().next());
match *obligation { match *obligation {
"A.1" => Ok(Some(vec![])), "A.1" => Ok(Some(vec![])),
"A.2" => Ok(Some(vec!["A.2.i", "A.2.ii"])), "A.2" => Ok(Some(vec!["A.2.i", "A.2.ii"])),
@ -119,7 +128,8 @@ fn success_in_grandchildren() {
assert!(err.is_empty()); assert!(err.is_empty());
let Outcome { completed: ok, errors: err, .. } = let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations::<(),_>(|obligation, _| { forest.process_obligations::<(),_>(|obligation, tree, _| {
assert_eq!(obligation.chars().next(), tree.chars().next());
match *obligation { match *obligation {
"A.2.i" => Ok(Some(vec!["A.2.i.a"])), "A.2.i" => Ok(Some(vec!["A.2.i.a"])),
"A.2.ii" => Ok(Some(vec![])), "A.2.ii" => Ok(Some(vec![])),
@ -130,7 +140,8 @@ fn success_in_grandchildren() {
assert!(err.is_empty()); assert!(err.is_empty());
let Outcome { completed: ok, errors: err, .. } = let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations::<(),_>(|obligation, _| { forest.process_obligations::<(),_>(|obligation, tree, _| {
assert_eq!(obligation.chars().next(), tree.chars().next());
match *obligation { match *obligation {
"A.2.i.a" => Ok(Some(vec![])), "A.2.i.a" => Ok(Some(vec![])),
_ => unreachable!(), _ => unreachable!(),
@ -140,7 +151,7 @@ fn success_in_grandchildren() {
assert!(err.is_empty()); assert!(err.is_empty());
let Outcome { completed: ok, errors: err, .. } = let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations::<(),_>(|_, _| unreachable!()); forest.process_obligations::<(),_>(|_, _, _| unreachable!());
assert!(ok.is_empty()); assert!(ok.is_empty());
assert!(err.is_empty()); assert!(err.is_empty());
} }
@ -150,9 +161,10 @@ fn to_errors_no_throw() {
// check that converting multiple children with common parent (A) // check that converting multiple children with common parent (A)
// only yields one of them (and does not panic, in particular). // only yields one of them (and does not panic, in particular).
let mut forest = ObligationForest::new(); let mut forest = ObligationForest::new();
forest.push_root("A"); forest.push_tree("A", "A");
let Outcome { completed: ok, errors: err, .. } = let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations::<(),_>(|obligation, _| { forest.process_obligations::<(),_>(|obligation, tree, _| {
assert_eq!(obligation.chars().next(), tree.chars().next());
match *obligation { match *obligation {
"A" => Ok(Some(vec!["A.1", "A.2", "A.3"])), "A" => Ok(Some(vec!["A.1", "A.2", "A.3"])),
_ => unreachable!(), _ => unreachable!(),
@ -168,10 +180,11 @@ fn to_errors_no_throw() {
fn backtrace() { fn backtrace() {
// check that converting multiple children with common parent (A) // check that converting multiple children with common parent (A)
// only yields one of them (and does not panic, in particular). // only yields one of them (and does not panic, in particular).
let mut forest: ObligationForest<&'static str> = ObligationForest::new(); let mut forest = ObligationForest::new();
forest.push_root("A"); forest.push_tree("A", "A");
let Outcome { completed: ok, errors: err, .. } = let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations::<(),_>(|obligation, mut backtrace| { forest.process_obligations::<(),_>(|obligation, tree, mut backtrace| {
assert_eq!(obligation.chars().next(), tree.chars().next());
assert!(backtrace.next().is_none()); assert!(backtrace.next().is_none());
match *obligation { match *obligation {
"A" => Ok(Some(vec!["A.1"])), "A" => Ok(Some(vec!["A.1"])),
@ -181,7 +194,8 @@ fn backtrace() {
assert!(ok.is_empty()); assert!(ok.is_empty());
assert!(err.is_empty()); assert!(err.is_empty());
let Outcome { completed: ok, errors: err, .. } = let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations::<(),_>(|obligation, mut backtrace| { forest.process_obligations::<(),_>(|obligation, tree, mut backtrace| {
assert_eq!(obligation.chars().next(), tree.chars().next());
assert!(backtrace.next().unwrap() == &"A"); assert!(backtrace.next().unwrap() == &"A");
assert!(backtrace.next().is_none()); assert!(backtrace.next().is_none());
match *obligation { match *obligation {
@ -192,7 +206,8 @@ fn backtrace() {
assert!(ok.is_empty()); assert!(ok.is_empty());
assert!(err.is_empty()); assert!(err.is_empty());
let Outcome { completed: ok, errors: err, .. } = let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations::<(),_>(|obligation, mut backtrace| { forest.process_obligations::<(),_>(|obligation, tree, mut backtrace| {
assert_eq!(obligation.chars().next(), tree.chars().next());
assert!(backtrace.next().unwrap() == &"A.1"); assert!(backtrace.next().unwrap() == &"A.1");
assert!(backtrace.next().unwrap() == &"A"); assert!(backtrace.next().unwrap() == &"A");
assert!(backtrace.next().is_none()); assert!(backtrace.next().is_none());

28
src/librustc_data_structures/obligation_forest/tree_index.rs Normal file
View file

@ -0,0 +1,28 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::u32;
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub struct TreeIndex {
index: u32
}
impl TreeIndex {
pub fn new(value: usize) -> TreeIndex {
assert!(value < (u32::MAX as usize));
TreeIndex { index: value as u32 }
}
pub fn get(self) -> usize {
self.index as usize
}
}