Skip to content

Speed up item_bodies for large match statements involving regions #57494

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Jan 13, 2019
Merged

Speed up item_bodies for large match statements involving regions #57494

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
07600c9
Drop "solved" constraints during region expansion
dotdash Jan 9, 2019
5f402b8
Add a fast path for identical regions in lub_concrete_regions
dotdash Jan 10, 2019
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
31 changes: 23 additions & 8 deletions src/librustc/infer/lexical_region_resolve/mod.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ use rustc_data_structures::graph::implementation::{
Direction, Graph, NodeIndex, INCOMING, OUTGOING,
};
use rustc_data_structures::indexed_vec::{Idx, IndexVec};
use smallvec::SmallVec;
use std::fmt;
use std::u32;
use ty::fold::TypeFoldable;
Expand Down Expand Up @@ -190,19 +191,24 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
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)
(self.expand_node(a_region, b_vid, b_data), false)
}
Constraint::VarSubVar(a_vid, b_vid) => match *var_values.value(a_vid) {
VarValue::ErrorValue => false,
VarValue::ErrorValue => (false, false),
VarValue::Value(a_region) => {
let b_node = var_values.value_mut(b_vid);
self.expand_node(a_region, b_vid, b_node)
let changed = self.expand_node(a_region, b_vid, b_node);
let retain = match *b_node {
VarValue::Value(ReStatic) | VarValue::ErrorValue => false,
_ => true
};
(changed, retain)
}
},
Constraint::RegSubReg(..) | Constraint::VarSubReg(..) => {
// These constraints are checked after expansion
// is done, in `collect_errors`.
false
(false, false)
}
}
})
Expand Down Expand Up @@ -268,6 +274,13 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {

fn lub_concrete_regions(&self, a: Region<'tcx>, b: Region<'tcx>) -> Region<'tcx> {
let tcx = self.tcx();

// Equal scopes can show up quite often, if the fixed point
// iteration converges slowly, skip them
if a == b {
return a;
}

match (a, b) {
(&ty::ReClosureBound(..), _)
| (_, &ty::ReClosureBound(..))
Expand Down Expand Up @@ -710,21 +723,23 @@ 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,
F: FnMut(&Constraint<'tcx>, &SubregionOrigin<'tcx>) -> (bool, bool),
{
let mut constraints: SmallVec<[_; 16]> = self.data.constraints.iter().collect();
let mut iteration = 0;
let mut changed = true;
while changed {
changed = false;
iteration += 1;
debug!("---- {} Iteration {}{}", "#", tag, iteration);
for (constraint, origin) in &self.data.constraints {
let edge_changed = body(constraint, origin);
constraints.retain(|(constraint, origin)| {
let (edge_changed, retain) = body(constraint, origin);
if edge_changed {
debug!("Updated due to constraint {:?}", constraint);
changed = true;
}
}
retain
});
}
debug!("---- {} Complete after {} iteration(s)", tag, iteration);
}
Expand Down