diff options
| -rw-r--r-- | src/librustc/ty/subst.rs | 28 |
1 files changed, 19 insertions, 9 deletions
diff --git a/src/librustc/ty/subst.rs b/src/librustc/ty/subst.rs index 57401ac19f3..f44e1533f52 100644 --- a/src/librustc/ty/subst.rs +++ b/src/librustc/ty/subst.rs @@ -17,6 +17,7 @@ use ty::fold::{TypeFoldable, TypeFolder, TypeVisitor}; use serialize::{self, Encodable, Encoder, Decodable, Decoder}; use syntax_pos::{Span, DUMMY_SP}; use rustc_data_structures::accumulate_vec::AccumulateVec; +use rustc_data_structures::array_vec::ArrayVec; use core::intrinsics; use std::fmt; @@ -176,7 +177,12 @@ impl<'a, 'gcx, 'tcx> Substs<'tcx> { where F: FnMut(&ty::GenericParamDef, &[Kind<'tcx>]) -> Kind<'tcx> { let defs = tcx.generics_of(def_id); - let mut substs = Vec::with_capacity(defs.count()); + let count = defs.count(); + let mut substs = if count <= 8 { + AccumulateVec::Array(ArrayVec::new()) + } else { + AccumulateVec::Heap(Vec::with_capacity(count)) + }; Substs::fill_item(&mut substs, tcx, defs, &mut mk_kind); tcx.intern_substs(&substs) } @@ -188,14 +194,15 @@ impl<'a, 'gcx, 'tcx> Substs<'tcx> { -> &'tcx Substs<'tcx> where F: FnMut(&ty::GenericParamDef, &[Kind<'tcx>]) -> Kind<'tcx> { - let defs = tcx.generics_of(def_id); - let mut result = Vec::with_capacity(defs.count()); - result.extend(self[..].iter().cloned()); - Substs::fill_single(&mut result, defs, &mut mk_kind); - tcx.intern_substs(&result) + Substs::for_item(tcx, def_id, |param, substs| { + match self.get(param.index as usize) { + Some(&kind) => kind, + None => mk_kind(param, substs), + } + }) } - fn fill_item<F>(substs: &mut Vec<Kind<'tcx>>, + fn fill_item<F>(substs: &mut AccumulateVec<[Kind<'tcx>; 8]>, tcx: TyCtxt<'a, 'gcx, 'tcx>, defs: &ty::Generics, mk_kind: &mut F) @@ -209,7 +216,7 @@ impl<'a, 'gcx, 'tcx> Substs<'tcx> { Substs::fill_single(substs, defs, mk_kind) } - fn fill_single<F>(substs: &mut Vec<Kind<'tcx>>, + fn fill_single<F>(substs: &mut AccumulateVec<[Kind<'tcx>; 8]>, defs: &ty::Generics, mk_kind: &mut F) where F: FnMut(&ty::GenericParamDef, &[Kind<'tcx>]) -> Kind<'tcx> @@ -217,7 +224,10 @@ impl<'a, 'gcx, 'tcx> Substs<'tcx> { for param in &defs.params { let kind = mk_kind(param, substs); assert_eq!(param.index as usize, substs.len()); - substs.push(kind); + match *substs { + AccumulateVec::Array(ref mut arr) => arr.push(kind), + AccumulateVec::Heap(ref mut vec) => vec.push(kind), + } } } |