Move always_storage_live_locals.

It's very closely related to `MaybeStorageLive` and `MaybeStorageDead`.
It's weird that it's currently in a different module.

Author: nnethercote

compiler/rustc_const_eval/src/check_consts/check.rs

@@ -18,8 +18,7 @@ use rustc_middle::span_bug;
 use rustc_middle::ty::adjustment::PointerCoercion;
 use rustc_middle::ty::{self, Ty, TypeVisitableExt};
 use rustc_mir_dataflow::Analysis;
-use rustc_mir_dataflow::impls::MaybeStorageLive;
-use rustc_mir_dataflow::storage::always_storage_live_locals;
+use rustc_mir_dataflow::impls::{MaybeStorageLive, always_storage_live_locals};
 use rustc_span::{Span, Symbol, sym};
 use rustc_trait_selection::traits::{
     Obligation, ObligationCause, ObligationCauseCode, ObligationCtxt,

compiler/rustc_const_eval/src/interpret/stack.rs

@@ -10,7 +10,7 @@ use rustc_index::IndexVec;
 use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::{bug, mir};
-use rustc_mir_dataflow::storage::always_storage_live_locals;
+use rustc_mir_dataflow::impls::always_storage_live_locals;
 use rustc_span::Span;
 use tracing::{info_span, instrument, trace};
 

compiler/rustc_mir_dataflow/src/impls/mod.rs

@@ -15,4 +15,6 @@ pub use self::initialized::{
 pub use self::liveness::{
     MaybeLiveLocals, MaybeTransitiveLiveLocals, TransferFunction as LivenessTransferFunction,
 };
-pub use self::storage_liveness::{MaybeRequiresStorage, MaybeStorageDead, MaybeStorageLive};
+pub use self::storage_liveness::{
+    MaybeRequiresStorage, MaybeStorageDead, MaybeStorageLive, always_storage_live_locals,
+};

compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs

@@ -7,6 +7,23 @@ use rustc_middle::mir::*;
 use super::MaybeBorrowedLocals;
 use crate::{Analysis, GenKill, ResultsCursor};
 
+/// The set of locals in a MIR body that do not have `StorageLive`/`StorageDead` annotations.
+///
+/// These locals have fixed storage for the duration of the body.
+pub fn always_storage_live_locals(body: &Body<'_>) -> BitSet<Local> {
+    let mut always_live_locals = BitSet::new_filled(body.local_decls.len());
+
+    for block in &*body.basic_blocks {
+        for statement in &block.statements {
+            if let StatementKind::StorageLive(l) | StatementKind::StorageDead(l) = statement.kind {
+                always_live_locals.remove(l);
+            }
+        }
+    }
+
+    always_live_locals
+}
+
 pub struct MaybeStorageLive<'a> {
     always_live_locals: Cow<'a, BitSet<Local>>,
 }

compiler/rustc_mir_dataflow/src/lib.rs

@@ -33,7 +33,6 @@ pub mod impls;
 pub mod move_paths;
 pub mod points;
 pub mod rustc_peek;
-pub mod storage;
 pub mod un_derefer;
 pub mod value_analysis;
 

compiler/rustc_mir_dataflow/src/storage.rs

@@ -70,8 +70,8 @@ use rustc_middle::ty::{
 use rustc_middle::{bug, span_bug};
 use rustc_mir_dataflow::impls::{
     MaybeBorrowedLocals, MaybeLiveLocals, MaybeRequiresStorage, MaybeStorageLive,
+    always_storage_live_locals,
 };
-use rustc_mir_dataflow::storage::always_storage_live_locals;
 use rustc_mir_dataflow::{Analysis, Results, ResultsVisitor};
 use rustc_span::Span;
 use rustc_span::def_id::{DefId, LocalDefId};

compiler/rustc_mir_transform/src/coroutine.rs

@@ -9,8 +9,7 @@ use rustc_index::bit_set::BitSet;
 use rustc_middle::mir::visit::{PlaceContext, Visitor};
 use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
-use rustc_mir_dataflow::impls::{MaybeStorageDead, MaybeStorageLive};
-use rustc_mir_dataflow::storage::always_storage_live_locals;
+use rustc_mir_dataflow::impls::{MaybeStorageDead, MaybeStorageLive, always_storage_live_locals};
 use rustc_mir_dataflow::{Analysis, ResultsCursor};
 
 pub(super) fn lint_body<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, when: String) {

compiler/rustc_mir_transform/src/lint.rs

@@ -8,8 +8,7 @@ use rustc_middle::mir::visit::*;
 use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
 use rustc_mir_dataflow::Analysis;
-use rustc_mir_dataflow::impls::MaybeStorageDead;
-use rustc_mir_dataflow::storage::always_storage_live_locals;
+use rustc_mir_dataflow::impls::{MaybeStorageDead, always_storage_live_locals};
 use tracing::{debug, instrument};
 
 use crate::ssa::{SsaLocals, StorageLiveLocals};