Remove references from some structs.

In all cases the struct can own the relevant thing instead of having a
reference to it. This makes the code simpler, and in some cases removes
a struct lifetime.

Author: nnethercote

compiler/rustc_mir_transform/src/dest_prop.rs

@@ -242,7 +242,7 @@ impl<'tcx> crate::MirPass<'tcx> for DestinationPropagation {
             }
             round_count += 1;
 
-            apply_merges(body, tcx, &merges, &merged_locals);
+            apply_merges(body, tcx, merges, merged_locals);
         }
 
         trace!(round_count);
@@ -281,20 +281,20 @@ struct Candidates {
 fn apply_merges<'tcx>(
     body: &mut Body<'tcx>,
     tcx: TyCtxt<'tcx>,
-    merges: &FxIndexMap<Local, Local>,
-    merged_locals: &BitSet<Local>,
+    merges: FxIndexMap<Local, Local>,
+    merged_locals: BitSet<Local>,
 ) {
     let mut merger = Merger { tcx, merges, merged_locals };
     merger.visit_body_preserves_cfg(body);
 }
 
-struct Merger<'a, 'tcx> {
+struct Merger<'tcx> {
     tcx: TyCtxt<'tcx>,
-    merges: &'a FxIndexMap<Local, Local>,
-    merged_locals: &'a BitSet<Local>,
+    merges: FxIndexMap<Local, Local>,
+    merged_locals: BitSet<Local>,
 }
 
-impl<'a, 'tcx> MutVisitor<'tcx> for Merger<'a, 'tcx> {
+impl<'tcx> MutVisitor<'tcx> for Merger<'tcx> {
     fn tcx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }

compiler/rustc_mir_transform/src/gvn.rs

@@ -125,7 +125,7 @@ impl<'tcx> crate::MirPass<'tcx> for GVN {
         // Clone dominators because we need them while mutating the body.
         let dominators = body.basic_blocks.dominators().clone();
 
-        let mut state = VnState::new(tcx, body, param_env, &ssa, &dominators, &body.local_decls);
+        let mut state = VnState::new(tcx, body, param_env, &ssa, dominators, &body.local_decls);
         ssa.for_each_assignment_mut(
             body.basic_blocks.as_mut_preserves_cfg(),
             |local, value, location| {
@@ -258,7 +258,7 @@ struct VnState<'body, 'tcx> {
     /// Cache the value of the `unsized_locals` features, to avoid fetching it repeatedly in a loop.
     feature_unsized_locals: bool,
     ssa: &'body SsaLocals,
-    dominators: &'body Dominators<BasicBlock>,
+    dominators: Dominators<BasicBlock>,
     reused_locals: BitSet<Local>,
 }
 
@@ -268,7 +268,7 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
         body: &Body<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
         ssa: &'body SsaLocals,
-        dominators: &'body Dominators<BasicBlock>,
+        dominators: Dominators<BasicBlock>,
         local_decls: &'body LocalDecls<'tcx>,
     ) -> Self {
         // Compute a rough estimate of the number of values in the body from the number of
@@ -1490,7 +1490,7 @@ impl<'tcx> VnState<'_, 'tcx> {
         let other = self.rev_locals.get(index)?;
         other
             .iter()
-            .find(|&&other| self.ssa.assignment_dominates(self.dominators, other, loc))
+            .find(|&&other| self.ssa.assignment_dominates(&self.dominators, other, loc))
             .copied()
     }
 }

compiler/rustc_mir_transform/src/jump_threading.rs

@@ -78,18 +78,16 @@ impl<'tcx> crate::MirPass<'tcx> for JumpThreading {
         }
 
         let param_env = tcx.param_env_reveal_all_normalized(def_id);
-        let map = Map::new(tcx, body, Some(MAX_PLACES));
-        let loop_headers = loop_headers(body);
 
-        let arena = DroplessArena::default();
+        let arena = &DroplessArena::default();
         let mut finder = TOFinder {
             tcx,
             param_env,
             ecx: InterpCx::new(tcx, DUMMY_SP, param_env, DummyMachine),
             body,
-            arena: &arena,
-            map: &map,
-            loop_headers: &loop_headers,
+            arena,
+            map: Map::new(tcx, body, Some(MAX_PLACES)),
+            loop_headers: loop_headers(body),
             opportunities: Vec::new(),
         };
 
@@ -105,7 +103,7 @@ impl<'tcx> crate::MirPass<'tcx> for JumpThreading {
 
         // Verify that we do not thread through a loop header.
         for to in opportunities.iter() {
-            assert!(to.chain.iter().all(|&block| !loop_headers.contains(block)));
+            assert!(to.chain.iter().all(|&block| !finder.loop_headers.contains(block)));
         }
         OpportunitySet::new(body, opportunities).apply(body);
     }
@@ -124,8 +122,8 @@ struct TOFinder<'tcx, 'a> {
     param_env: ty::ParamEnv<'tcx>,
     ecx: InterpCx<'tcx, DummyMachine>,
     body: &'a Body<'tcx>,
-    map: &'a Map<'tcx>,
-    loop_headers: &'a BitSet<BasicBlock>,
+    map: Map<'tcx>,
+    loop_headers: BitSet<BasicBlock>,
     /// We use an arena to avoid cloning the slices when cloning `state`.
     arena: &'a DroplessArena,
     opportunities: Vec<ThreadingOpportunity>,
@@ -223,7 +221,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
             }))
         };
         let conds = ConditionSet(conds);
-        state.insert_value_idx(discr, conds, self.map);
+        state.insert_value_idx(discr, conds, &self.map);
 
         self.find_opportunity(bb, state, cost, 0);
     }
@@ -264,7 +262,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
             //   _1 = 5 // Whatever happens here, it won't change the result of a `SwitchInt`.
             //   _1 = 6
             if let Some((lhs, tail)) = self.mutated_statement(stmt) {
-                state.flood_with_tail_elem(lhs.as_ref(), tail, self.map, ConditionSet::BOTTOM);
+                state.flood_with_tail_elem(lhs.as_ref(), tail, &self.map, ConditionSet::BOTTOM);
             }
         }
 
@@ -370,7 +368,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
             self.opportunities.push(ThreadingOpportunity { chain: vec![bb], target: c.target })
         };
 
-        if let Some(conditions) = state.try_get_idx(lhs, self.map)
+        if let Some(conditions) = state.try_get_idx(lhs, &self.map)
             && let Immediate::Scalar(Scalar::Int(int)) = *rhs
         {
             conditions.iter_matches(int).for_each(register_opportunity);
@@ -406,7 +404,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
                 }
             },
             &mut |place, op| {
-                if let Some(conditions) = state.try_get_idx(place, self.map)
+                if let Some(conditions) = state.try_get_idx(place, &self.map)
                     && let Ok(imm) = self.ecx.read_immediate_raw(op)
                     && let Some(imm) = imm.right()
                     && let Immediate::Scalar(Scalar::Int(int)) = *imm
@@ -441,7 +439,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
             // Transfer the conditions on the copied rhs.
             Operand::Move(rhs) | Operand::Copy(rhs) => {
                 let Some(rhs) = self.map.find(rhs.as_ref()) else { return };
-                state.insert_place_idx(rhs, lhs, self.map);
+                state.insert_place_idx(rhs, lhs, &self.map);
             }
         }
     }
@@ -461,7 +459,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
             Rvalue::CopyForDeref(rhs) => self.process_operand(bb, lhs, &Operand::Copy(*rhs), state),
             Rvalue::Discriminant(rhs) => {
                 let Some(rhs) = self.map.find_discr(rhs.as_ref()) else { return };
-                state.insert_place_idx(rhs, lhs, self.map);
+                state.insert_place_idx(rhs, lhs, &self.map);
             }
             // If we expect `lhs ?= A`, we have an opportunity if we assume `constant == A`.
             Rvalue::Aggregate(box ref kind, ref operands) => {
@@ -492,10 +490,10 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
             }
             // Transfer the conditions on the copy rhs, after inversing polarity.
             Rvalue::UnaryOp(UnOp::Not, Operand::Move(place) | Operand::Copy(place)) => {
-                let Some(conditions) = state.try_get_idx(lhs, self.map) else { return };
+                let Some(conditions) = state.try_get_idx(lhs, &self.map) else { return };
                 let Some(place) = self.map.find(place.as_ref()) else { return };
                 let conds = conditions.map(self.arena, Condition::inv);
-                state.insert_value_idx(place, conds, self.map);
+                state.insert_value_idx(place, conds, &self.map);
             }
             // We expect `lhs ?= A`. We found `lhs = Eq(rhs, B)`.
             // Create a condition on `rhs ?= B`.
@@ -504,7 +502,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
                 box (Operand::Move(place) | Operand::Copy(place), Operand::Constant(value))
                 | box (Operand::Constant(value), Operand::Move(place) | Operand::Copy(place)),
             ) => {
-                let Some(conditions) = state.try_get_idx(lhs, self.map) else { return };
+                let Some(conditions) = state.try_get_idx(lhs, &self.map) else { return };
                 let Some(place) = self.map.find(place.as_ref()) else { return };
                 let equals = match op {
                     BinOp::Eq => ScalarInt::TRUE,
@@ -528,7 +526,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
                     polarity: if c.matches(equals) { Polarity::Eq } else { Polarity::Ne },
                     ..c
                 });
-                state.insert_value_idx(place, conds, self.map);
+                state.insert_value_idx(place, conds, &self.map);
             }
 
             _ => {}
@@ -583,7 +581,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
             StatementKind::Intrinsic(box NonDivergingIntrinsic::Assume(
                 Operand::Copy(place) | Operand::Move(place),
             )) => {
-                let Some(conditions) = state.try_get(place.as_ref(), self.map) else { return };
+                let Some(conditions) = state.try_get(place.as_ref(), &self.map) else { return };
                 conditions.iter_matches(ScalarInt::TRUE).for_each(register_opportunity);
             }
             StatementKind::Assign(box (lhs_place, rhs)) => {
@@ -631,7 +629,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
         // We can recurse through this terminator.
         let mut state = state();
         if let Some(place_to_flood) = place_to_flood {
-            state.flood_with(place_to_flood.as_ref(), self.map, ConditionSet::BOTTOM);
+            state.flood_with(place_to_flood.as_ref(), &self.map, ConditionSet::BOTTOM);
         }
         self.find_opportunity(bb, state, cost.clone(), depth + 1);
     }
@@ -650,7 +648,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
         let Some(discr) = discr.place() else { return };
         let discr_ty = discr.ty(self.body, self.tcx).ty;
         let Ok(discr_layout) = self.ecx.layout_of(discr_ty) else { return };
-        let Some(conditions) = state.try_get(discr.as_ref(), self.map) else { return };
+        let Some(conditions) = state.try_get(discr.as_ref(), &self.map) else { return };
 
         if let Some((value, _)) = targets.iter().find(|&(_, target)| target == target_bb) {
             let Some(value) = ScalarInt::try_from_uint(value, discr_layout.size) else { return };

compiler/rustc_mir_transform/src/lib.rs

@@ -223,24 +223,26 @@ fn is_mir_available(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
 /// MIR associated with them.
 fn mir_keys(tcx: TyCtxt<'_>, (): ()) -> FxIndexSet<LocalDefId> {
     // All body-owners have MIR associated with them.
-    let mut set: FxIndexSet<_> = tcx.hir().body_owners().collect();
+    let set: FxIndexSet<_> = tcx.hir().body_owners().collect();
 
     // Additionally, tuple struct/variant constructors have MIR, but
     // they don't have a BodyId, so we need to build them separately.
-    struct GatherCtors<'a> {
-        set: &'a mut FxIndexSet<LocalDefId>,
+    struct GatherCtors {
+        set: FxIndexSet<LocalDefId>,
     }
-    impl<'tcx> Visitor<'tcx> for GatherCtors<'_> {
+    impl<'tcx> Visitor<'tcx> for GatherCtors {
         fn visit_variant_data(&mut self, v: &'tcx hir::VariantData<'tcx>) {
             if let hir::VariantData::Tuple(_, _, def_id) = *v {
                 self.set.insert(def_id);
             }
             intravisit::walk_struct_def(self, v)
         }
     }
-    tcx.hir().visit_all_item_likes_in_crate(&mut GatherCtors { set: &mut set });
 
-    set
+    let mut gather_ctors = GatherCtors { set };
+    tcx.hir().visit_all_item_likes_in_crate(&mut gather_ctors);
+
+    gather_ctors.set
 }
 
 fn mir_const_qualif(tcx: TyCtxt<'_>, def: LocalDefId) -> ConstQualifs {

compiler/rustc_mir_transform/src/mentioned_items.rs

@@ -10,7 +10,7 @@ pub(super) struct MentionedItems;
 struct MentionedItemsVisitor<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     body: &'a mir::Body<'tcx>,
-    mentioned_items: &'a mut Vec<Spanned<MentionedItem<'tcx>>>,
+    mentioned_items: Vec<Spanned<MentionedItem<'tcx>>>,
 }
 
 impl<'tcx> crate::MirPass<'tcx> for MentionedItems {
@@ -23,9 +23,9 @@ impl<'tcx> crate::MirPass<'tcx> for MentionedItems {
     }
 
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut mir::Body<'tcx>) {
-        let mut mentioned_items = Vec::new();
-        MentionedItemsVisitor { tcx, body, mentioned_items: &mut mentioned_items }.visit_body(body);
-        body.set_mentioned_items(mentioned_items);
+        let mut visitor = MentionedItemsVisitor { tcx, body, mentioned_items: Vec::new() };
+        visitor.visit_body(body);
+        body.set_mentioned_items(visitor.mentioned_items);
     }
 }
 

compiler/rustc_mir_transform/src/ref_prop.rs

@@ -253,11 +253,8 @@ fn compute_replacement<'tcx>(
 
     debug!(?targets);
 
-    let mut finder = ReplacementFinder {
-        targets: &mut targets,
-        can_perform_opt,
-        allowed_replacements: FxHashSet::default(),
-    };
+    let mut finder =
+        ReplacementFinder { targets, can_perform_opt, allowed_replacements: FxHashSet::default() };
     let reachable_blocks = traversal::reachable_as_bitset(body);
     for (bb, bbdata) in body.basic_blocks.iter_enumerated() {
         // Only visit reachable blocks as we rely on dataflow.
@@ -269,19 +266,19 @@ fn compute_replacement<'tcx>(
     let allowed_replacements = finder.allowed_replacements;
     return Replacer {
         tcx,
-        targets,
+        targets: finder.targets,
         storage_to_remove,
         allowed_replacements,
         any_replacement: false,
     };
 
-    struct ReplacementFinder<'a, 'tcx, F> {
-        targets: &'a mut IndexVec<Local, Value<'tcx>>,
+    struct ReplacementFinder<'tcx, F> {
+        targets: IndexVec<Local, Value<'tcx>>,
         can_perform_opt: F,
         allowed_replacements: FxHashSet<(Local, Location)>,
     }
 
-    impl<'tcx, F> Visitor<'tcx> for ReplacementFinder<'_, 'tcx, F>
+    impl<'tcx, F> Visitor<'tcx> for ReplacementFinder<'tcx, F>
     where
         F: FnMut(Place<'tcx>, Location) -> bool,
     {

compiler/rustc_mir_transform/src/required_consts.rs

@@ -1,26 +1,21 @@
 use rustc_middle::mir::visit::Visitor;
 use rustc_middle::mir::{traversal, Body, ConstOperand, Location};
 
-pub(super) struct RequiredConstsVisitor<'a, 'tcx> {
-    required_consts: &'a mut Vec<ConstOperand<'tcx>>,
+pub(super) struct RequiredConstsVisitor<'tcx> {
+    required_consts: Vec<ConstOperand<'tcx>>,
 }
 
-impl<'a, 'tcx> RequiredConstsVisitor<'a, 'tcx> {
-    fn new(required_consts: &'a mut Vec<ConstOperand<'tcx>>) -> Self {
-        RequiredConstsVisitor { required_consts }
-    }
-
+impl<'tcx> RequiredConstsVisitor<'tcx> {
     pub(super) fn compute_required_consts(body: &mut Body<'tcx>) {
-        let mut required_consts = Vec::new();
-        let mut required_consts_visitor = RequiredConstsVisitor::new(&mut required_consts);
+        let mut visitor = RequiredConstsVisitor { required_consts: Vec::new() };
         for (bb, bb_data) in traversal::reverse_postorder(&body) {
-            required_consts_visitor.visit_basic_block_data(bb, bb_data);
+            visitor.visit_basic_block_data(bb, bb_data);
         }
-        body.set_required_consts(required_consts);
+        body.set_required_consts(visitor.required_consts);
     }
 }
 
-impl<'tcx> Visitor<'tcx> for RequiredConstsVisitor<'_, 'tcx> {
+impl<'tcx> Visitor<'tcx> for RequiredConstsVisitor<'tcx> {
     fn visit_const_operand(&mut self, constant: &ConstOperand<'tcx>, _: Location) {
         if constant.const_.is_required_const() {
             self.required_consts.push(*constant);