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Tweak expand_node #57719

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merged 2 commits into from
Jan 19, 2019
Merged

Tweak expand_node #57719

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5576833
Remove unneeded `origin` arg from `iterate_until_fixed_point`'s closure.
nnethercote Jan 17, 2019
92fd6f9
Inline `expand_node`.
nnethercote Jan 17, 2019
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36 changes: 20 additions & 16 deletions src/librustc/infer/lexical_region_resolve/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -186,34 +186,39 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
}

fn expansion(&self, var_values: &mut LexicalRegionResolutions<'tcx>) {
self.iterate_until_fixed_point("Expansion", |constraint, origin| {
debug!("expansion: constraint={:?} origin={:?}", constraint, origin);
match *constraint {
self.iterate_until_fixed_point("Expansion", |constraint| {
debug!("expansion: constraint={:?}", constraint);
let (a_region, b_vid, b_data, retain) = match *constraint {
Constraint::RegSubVar(a_region, b_vid) => {
let b_data = var_values.value_mut(b_vid);
(self.expand_node(a_region, b_vid, b_data), false)
(a_region, b_vid, b_data, false)
}
Constraint::VarSubVar(a_vid, b_vid) => match *var_values.value(a_vid) {
VarValue::ErrorValue => (false, false),
VarValue::ErrorValue => return (false, false),
VarValue::Value(a_region) => {
let b_node = var_values.value_mut(b_vid);
let changed = self.expand_node(a_region, b_vid, b_node);
let retain = match *b_node {
let b_data = var_values.value_mut(b_vid);
let retain = match *b_data {
VarValue::Value(ReStatic) | VarValue::ErrorValue => false,
_ => true
};
(changed, retain)
(a_region, b_vid, b_data, retain)
}
},
Constraint::RegSubReg(..) | Constraint::VarSubReg(..) => {
// These constraints are checked after expansion
// is done, in `collect_errors`.
(false, false)
return (false, false)
}
}
};

let changed = self.expand_node(a_region, b_vid, b_data);
(changed, retain)
})
}

// This function is very hot in some workloads. There's a single callsite
// so always inlining is ok even though it's large.
#[inline(always)]
fn expand_node(
&self,
a_region: Region<'tcx>,
Expand Down Expand Up @@ -722,18 +727,17 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
}

fn iterate_until_fixed_point<F>(&self, tag: &str, mut body: F)
where
F: FnMut(&Constraint<'tcx>, &SubregionOrigin<'tcx>) -> (bool, bool),
where F: FnMut(&Constraint<'tcx>) -> (bool, bool),
{
let mut constraints: SmallVec<[_; 16]> = self.data.constraints.iter().collect();
let mut constraints: SmallVec<[_; 16]> = self.data.constraints.keys().collect();
let mut iteration = 0;
let mut changed = true;
while changed {
changed = false;
iteration += 1;
debug!("---- {} Iteration {}{}", "#", tag, iteration);
constraints.retain(|(constraint, origin)| {
let (edge_changed, retain) = body(constraint, origin);
constraints.retain(|constraint| {
let (edge_changed, retain) = body(constraint);
if edge_changed {
debug!("Updated due to constraint {:?}", constraint);
changed = true;
Expand Down