Rollup merge of rust-lang#105659 - JakobDegen:storage-live-borrow, r=davidtwco

Don't require owned data in `MaybeStorageLive`

Small improvement that avoids a clone. I don't expect this to have any noticeable perf effects, but better to have it than not to.

r? ``@tmiasko``

Author: matthiaskrgr

compiler/rustc_const_eval/src/transform/validate.rs

@@ -52,7 +52,7 @@ impl<'tcx> MirPass<'tcx> for Validator {
         };
 
         let always_live_locals = always_storage_live_locals(body);
-        let storage_liveness = MaybeStorageLive::new(always_live_locals)
+        let storage_liveness = MaybeStorageLive::new(std::borrow::Cow::Owned(always_live_locals))
             .into_engine(tcx, body)
             .iterate_to_fixpoint()
             .into_results_cursor(body);
@@ -79,7 +79,7 @@ struct TypeChecker<'a, 'tcx> {
     param_env: ParamEnv<'tcx>,
     mir_phase: MirPhase,
     reachable_blocks: BitSet<BasicBlock>,
-    storage_liveness: ResultsCursor<'a, 'tcx, MaybeStorageLive>,
+    storage_liveness: ResultsCursor<'a, 'tcx, MaybeStorageLive<'static>>,
     place_cache: Vec<PlaceRef<'tcx>>,
     value_cache: Vec<u128>,
 }

compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs

@@ -3,20 +3,21 @@ pub use super::*;
 use crate::{CallReturnPlaces, GenKill, Results, ResultsRefCursor};
 use rustc_middle::mir::visit::{NonMutatingUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::*;
+use std::borrow::Cow;
 use std::cell::RefCell;
 
 #[derive(Clone)]
-pub struct MaybeStorageLive {
-    always_live_locals: BitSet<Local>,
+pub struct MaybeStorageLive<'a> {
+    always_live_locals: Cow<'a, BitSet<Local>>,
 }
 
-impl MaybeStorageLive {
-    pub fn new(always_live_locals: BitSet<Local>) -> Self {
+impl<'a> MaybeStorageLive<'a> {
+    pub fn new(always_live_locals: Cow<'a, BitSet<Local>>) -> Self {
         MaybeStorageLive { always_live_locals }
     }
 }
 
-impl<'tcx> crate::AnalysisDomain<'tcx> for MaybeStorageLive {
+impl<'tcx, 'a> crate::AnalysisDomain<'tcx> for MaybeStorageLive<'a> {
     type Domain = BitSet<Local>;
 
     const NAME: &'static str = "maybe_storage_live";
@@ -38,7 +39,7 @@ impl<'tcx> crate::AnalysisDomain<'tcx> for MaybeStorageLive {
     }
 }
 
-impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeStorageLive {
+impl<'tcx, 'a> crate::GenKillAnalysis<'tcx> for MaybeStorageLive<'a> {
     type Idx = Local;
 
     fn statement_effect(

compiler/rustc_mir_transform/src/generator.rs

@@ -490,7 +490,7 @@ fn locals_live_across_suspend_points<'tcx>(
 
     // Calculate when MIR locals have live storage. This gives us an upper bound of their
     // lifetimes.
-    let mut storage_live = MaybeStorageLive::new(always_live_locals.clone())
+    let mut storage_live = MaybeStorageLive::new(std::borrow::Cow::Borrowed(always_live_locals))
         .into_engine(tcx, body_ref)
         .iterate_to_fixpoint()
         .into_results_cursor(body_ref);