OpenE2K/rust
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Specialize the stalled_on handling in process_obligation().

Browse Source 
Optimizing for the common numbers of entries in `stalled_on` wins about
4% on `keccak` and `inflate`.
This commit is contained in:
Nicholas Nethercote 2019-09-18 14:50:48 +10:00
parent aaff05bd1c
commit acf7d4dcdb
2 changed files with 38 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
src/librustc/infer/mod.rs
View File

@ -1600,8 +1600,8 @@ impl<'a, 'tcx> ShallowResolver<'a, 'tcx> {
// `resolver.shallow_resolve_changed(ty)` is equivalent to
// `resolver.shallow_resolve(ty) != ty`, but more efficient. It's always
// inlined, despite being large, because it has a single call site that is
// extremely hot.
// inlined, despite being large, because it has only two call sites that
// are extremely hot.
#[inline(always)]
pub fn shallow_resolve_changed(&mut self, typ: Ty<'tcx>) -> bool {
match typ.sty {

55
src/librustc/traits/fulfill.rs
View File

@ -256,29 +256,46 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
&mut self,
pending_obligation: &mut Self::Obligation,
) -> ProcessResult<Self::Obligation, Self::Error> {
// If we were stalled on some unresolved variables, first check
// whether any of them have been resolved; if not, don't bother
// doing more work yet
if !pending_obligation.stalled_on.is_empty() {
let mut changed = false;
// This `for` loop was once a call to `all()`, but this lower-level
// form was a perf win. See #64545 for details.
for &ty in &pending_obligation.stalled_on {
if ShallowResolver::new(self.selcx.infcx()).shallow_resolve_changed(ty) {
changed = true;
break;
}
// If we were stalled on some unresolved variables, first check whether
// any of them have been resolved; if not, don't bother doing more work
// yet.
let change = match pending_obligation.stalled_on.len() {
// Match arms are in order of frequency, which matters because this
// code is so hot. 1 and 0 dominate; 2+ is fairly rare.
1 => {
let ty = pending_obligation.stalled_on[0];
ShallowResolver::new(self.selcx.infcx()).shallow_resolve_changed(ty)
}
if !changed {
debug!("process_predicate: pending obligation {:?} still stalled on {:?}",
self.selcx.infcx()
.resolve_vars_if_possible(&pending_obligation.obligation),
pending_obligation.stalled_on);
return ProcessResult::Unchanged;
0 => {
// In this case we haven't changed, but wish to make a change.
true
}
pending_obligation.stalled_on = vec![];
_ => {
// This `for` loop was once a call to `all()`, but this lower-level
// form was a perf win. See #64545 for details.
(|| {
for &ty in &pending_obligation.stalled_on {
if ShallowResolver::new(self.selcx.infcx()).shallow_resolve_changed(ty) {
return true;
}
}
false
})()
}
};
if !change {
debug!("process_predicate: pending obligation {:?} still stalled on {:?}",
self.selcx.infcx()
.resolve_vars_if_possible(&pending_obligation.obligation),
pending_obligation.stalled_on);
return ProcessResult::Unchanged;
}
// This part of the code is much colder.
pending_obligation.stalled_on.truncate(0);
let obligation = &mut pending_obligation.obligation;
if obligation.predicate.has_infer_types() {