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dylan_DPC 2018-07-21 17:21:04 +05:30
parent 7db3324340
commit a4c0d369b6
1 changed files with 22 additions and 3 deletions
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25
src/librustc_mir/borrow_check/nll/liveness_map.rs
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@ -8,25 +8,41 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! For the NLL computation, we need to compute liveness, but only for those
//! local variables whose types contain regions. The others are not of interest
//! to us. This file defines a new index type (LocalWithRegion) that indexes into
//! a list of "variables whose type contain regions". It also defines a map from
//! Local to LocalWithRegion and vice versa -- this map can be given to the
//! liveness code so that it only operates over variables with regions in their
//! types, instead of all variables.
use rustc::ty::TypeFoldable;
use rustc_data_structures::indexed_vec::IndexVec;
use rustc::mir::{Mir, Local};
use util::liveness::LiveVariableMap;
use rustc_data_structures::indexed_vec::Idx;
use rustc::ty::TypeFoldable;
use rustc_data_structures::indexed_vec::Idx;
/// Map between Local and LocalWithRegion indices: this map is supplied to the
/// liveness code so that it will only analyze those variables whose types
/// contain regions.
crate struct NllLivenessMap {
/// For each local variable, contains either None (if the type has no regions)
/// or Some(i) with a suitable index.
pub from_local: IndexVec<Local, Option<LocalWithRegion>>,
/// For each LocalWithRegion, maps back to the original Local index.
pub to_local: IndexVec<LocalWithRegion, Local>,
}
impl LiveVariableMap for NllLivenessMap {
type LiveVar = LocalWithRegion;
fn from_local(&self, local: Local) -> Option<Self::LiveVar> {
self.from_local[local]
}
type LiveVar = LocalWithRegion;
fn from_live_var(&self, local: Self::LiveVar) -> Local {
self.to_local[local]
}
@ -37,6 +53,8 @@ impl LiveVariableMap for NllLivenessMap {
}
impl NllLivenessMap {
/// Iterates over the variables in Mir and assigns each Local whose type contains
/// regions a LocalWithRegion index. Returns a map for converting back and forth.
pub fn compute(mir: &Mir) -> Self {
let mut to_local = IndexVec::default();
let from_local: IndexVec<Local,Option<_>> = mir
@ -55,4 +73,5 @@ impl NllLivenessMap {
}
}
/// Index given to each local variable whose type contains a region.
newtype_index!(LocalWithRegion);