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Auto merge of #31680 - arielb1:fast-fulfill, r=nikomatsakis

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this improves typeck performance by 5% (LLVM times are still huge).

Basically fixes #25916 (still O(n^2), but the example takes <1s to
compile).

r? @nikomatsakis
This commit is contained in:
bors 2016-02-16 22:35:09 +00:00
commit 57c357d891
3 changed files with 68 additions and 14 deletions
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43
src/librustc/middle/traits/fulfill.rs
View File

@ -10,7 +10,7 @@
use dep_graph::DepGraph;
use middle::infer::InferCtxt;
use middle::ty::{self, Ty, TypeFoldable};
use middle::ty::{self, Ty, TypeFoldable, ToPolyTraitRef};
use rustc_data_structures::obligation_forest::{Backtrace, ObligationForest, Error};
use std::iter;
use syntax::ast;
@ -417,6 +417,21 @@ fn process_predicate<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
}
}
/// Return the set of type variables contained in a trait ref
fn trait_ref_type_vars<'a, 'tcx>(selcx: &mut SelectionContext<'a, 'tcx>,
t: ty::PolyTraitRef<'tcx>) -> Vec<Ty<'tcx>>
{
t.skip_binder() // ok b/c this check doesn't care about regions
.input_types()
.iter()
.map(|t| selcx.infcx().resolve_type_vars_if_possible(t))
.filter(|t| t.has_infer_types())
.flat_map(|t| t.walk())
.filter(|t| match t.sty { ty::TyInfer(_) => true, _ => false })
.collect()
}
/// Processes a predicate obligation and returns either:
/// - `Ok(Some(v))` if the predicate is true, presuming that `v` are also true
/// - `Ok(None)` if we don't have enough info to be sure
@ -433,7 +448,7 @@ fn process_predicate1<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
// doing more work yet
if !pending_obligation.stalled_on.is_empty() {
if pending_obligation.stalled_on.iter().all(|&ty| {
let resolved_ty = selcx.infcx().resolve_type_vars_if_possible(&ty);
let resolved_ty = selcx.infcx().shallow_resolve(&ty);
resolved_ty == ty // nothing changed here
}) {
debug!("process_predicate: pending obligation {:?} still stalled on {:?}",
@ -493,14 +508,7 @@ fn process_predicate1<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
// of its type, and those types are resolved at
// the same time.
pending_obligation.stalled_on =
data.skip_binder() // ok b/c this check doesn't care about regions
.input_types()
.iter()
.map(|t| selcx.infcx().resolve_type_vars_if_possible(t))
.filter(|t| t.has_infer_types())
.flat_map(|t| t.walk())
.filter(|t| match t.sty { ty::TyInfer(_) => true, _ => false })
.collect();
trait_ref_type_vars(selcx, data.to_poly_trait_ref());
debug!("process_predicate: pending obligation {:?} now stalled on {:?}",
selcx.infcx().resolve_type_vars_if_possible(obligation),
@ -568,6 +576,11 @@ fn process_predicate1<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
ty::Predicate::Projection(ref data) => {
let project_obligation = obligation.with(data.clone());
match project::poly_project_and_unify_type(selcx, &project_obligation) {
Ok(None) => {
pending_obligation.stalled_on =
trait_ref_type_vars(selcx, data.to_poly_trait_ref());
Ok(None)
}
Ok(v) => Ok(v),
Err(e) => Err(CodeProjectionError(e))
}
@ -582,8 +595,14 @@ fn process_predicate1<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
}
ty::Predicate::WellFormed(ty) => {
Ok(ty::wf::obligations(selcx.infcx(), obligation.cause.body_id,
ty, obligation.cause.span))
match ty::wf::obligations(selcx.infcx(), obligation.cause.body_id,
ty, obligation.cause.span) {
None => {
pending_obligation.stalled_on = vec![ty];
Ok(None)
}
s => Ok(s)
}
}
}
}

4
src/librustc/middle/ty/mod.rs
View File

@ -917,7 +917,7 @@ impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
self.map_bound_ref(|trait_pred| trait_pred.trait_ref.clone())
self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
}
}
@ -928,7 +928,7 @@ impl<'tcx> ToPolyTraitRef<'tcx> for PolyProjectionPredicate<'tcx> {
// This is because here `self` has a `Binder` and so does our
// return value, so we are preserving the number of binding
// levels.
ty::Binder(self.0.projection_ty.trait_ref.clone())
ty::Binder(self.0.projection_ty.trait_ref)
}
}

35
src/test/run-pass/issue-25916.rs Normal file
View File

@ -0,0 +1,35 @@
// Copyright 2016 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.
fn main() {
macro_rules! f {
() => { 0 + 0 }
}
// 16 per line
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();f!();
}