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Use explicit iteration instead of all() in process_obligation().

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Amazingly enough, this is a 3.5% instruction count win on `keccak`.
This commit is contained in:
Nicholas Nethercote 2019-09-17 16:48:21 +10:00
parent 7f6e160875
commit 82e5c6ee65
1 changed files with 11 additions and 4 deletions
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15
src/librustc/traits/fulfill.rs
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@ -256,15 +256,22 @@ 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
// 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() {
if pending_obligation.stalled_on.iter().all(|&ty| {
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 {
// Use the force-inlined variant of shallow_resolve() because this code is hot.
let resolved = ShallowResolver::new(self.selcx.infcx()).inlined_shallow_resolve(ty);
resolved == ty // nothing changed here
}) {
if resolved != ty {
changed = true;
break;
}
}
if !changed {
debug!("process_predicate: pending obligation {:?} still stalled on {:?}",
self.selcx.infcx()
.resolve_vars_if_possible(&pending_obligation.obligation),