Don't require owned data in MaybeStorageDead

Author: tmiasko

compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs

@@ -81,17 +81,17 @@ impl<'tcx, 'a> crate::GenKillAnalysis<'tcx> for MaybeStorageLive<'a> {
 }
 
 #[derive(Clone)]
-pub struct MaybeStorageDead {
-    always_live_locals: BitSet<Local>,
+pub struct MaybeStorageDead<'a> {
+    always_live_locals: Cow<'a, BitSet<Local>>,
 }
 
-impl MaybeStorageDead {
-    pub fn new(always_live_locals: BitSet<Local>) -> Self {
+impl<'a> MaybeStorageDead<'a> {
+    pub fn new(always_live_locals: Cow<'a, BitSet<Local>>) -> Self {
         MaybeStorageDead { always_live_locals }
     }
 }
 
-impl<'tcx> crate::AnalysisDomain<'tcx> for MaybeStorageDead {
+impl<'tcx, 'a> crate::AnalysisDomain<'tcx> for MaybeStorageDead<'a> {
     type Domain = BitSet<Local>;
 
     const NAME: &'static str = "maybe_storage_dead";
@@ -112,7 +112,7 @@ impl<'tcx> crate::AnalysisDomain<'tcx> for MaybeStorageDead {
     }
 }
 
-impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeStorageDead {
+impl<'tcx, 'a> crate::GenKillAnalysis<'tcx> for MaybeStorageDead<'a> {
     type Idx = Local;
 
     fn domain_size(&self, body: &Body<'tcx>) -> usize {

compiler/rustc_mir_transform/src/ref_prop.rs

@@ -7,6 +7,7 @@ use rustc_middle::ty::TyCtxt;
 use rustc_mir_dataflow::impls::MaybeStorageDead;
 use rustc_mir_dataflow::storage::always_storage_live_locals;
 use rustc_mir_dataflow::Analysis;
+use std::borrow::Cow;
 
 use crate::ssa::{SsaLocals, StorageLiveLocals};
 
@@ -120,7 +121,7 @@ fn compute_replacement<'tcx>(
 
     // Compute `MaybeStorageDead` dataflow to check that we only replace when the pointee is
     // definitely live.
-    let mut maybe_dead = MaybeStorageDead::new(always_live_locals)
+    let mut maybe_dead = MaybeStorageDead::new(Cow::Owned(always_live_locals))
         .into_engine(tcx, body)
         .iterate_to_fixpoint()
         .into_results_cursor(body);