Merging upstream version 1.74.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

11 files changed, 250 insertions, 117 deletions

diff --git a/compiler/rustc_mir_dataflow/src/elaborate_drops.rs b/compiler/rustc_mir_dataflow/src/elaborate_drops.rs
index 9e02b0271..c9991e499 100644
--- a/compiler/rustc_mir_dataflow/src/elaborate_drops.rs
+++ b/compiler/rustc_mir_dataflow/src/elaborate_drops.rs
@@ -80,7 +80,7 @@ impl Unwind {
     fn into_action(self) -> UnwindAction {
         match self {
             Unwind::To(bb) => UnwindAction::Cleanup(bb),
-            Unwind::InCleanup => UnwindAction::Terminate,
+            Unwind::InCleanup => UnwindAction::Terminate(UnwindTerminateReason::InCleanup),
         }
     }
 
@@ -194,6 +194,7 @@ where
     D: DropElaborator<'b, 'tcx>,
     'tcx: 'b,
 {
+    #[instrument(level = "trace", skip(self), ret)]
     fn place_ty(&self, place: Place<'tcx>) -> Ty<'tcx> {
         place.ty(self.elaborator.body(), self.tcx()).ty
     }
@@ -220,11 +221,9 @@ where
     //
     // FIXME: I think we should just control the flags externally,
     // and then we do not need this machinery.
+    #[instrument(level = "debug")]
     pub fn elaborate_drop(&mut self, bb: BasicBlock) {
-        debug!("elaborate_drop({:?}, {:?})", bb, self);
-        let style = self.elaborator.drop_style(self.path, DropFlagMode::Deep);
-        debug!("elaborate_drop({:?}, {:?}): live - {:?}", bb, self, style);
-        match style {
+        match self.elaborator.drop_style(self.path, DropFlagMode::Deep) {
             DropStyle::Dead => {
                 self.elaborator
                     .patch()
@@ -973,10 +972,10 @@ where
     }
 
     fn constant_usize(&self, val: u16) -> Operand<'tcx> {
-        Operand::Constant(Box::new(Constant {
+        Operand::Constant(Box::new(ConstOperand {
             span: self.source_info.span,
             user_ty: None,
-            literal: ConstantKind::from_usize(self.tcx(), val.into()),
+            const_: Const::from_usize(self.tcx(), val.into()),
         }))
     }
 
diff --git a/compiler/rustc_mir_dataflow/src/framework/direction.rs b/compiler/rustc_mir_dataflow/src/framework/direction.rs
index 8a9e37c5a..70451edd5 100644
--- a/compiler/rustc_mir_dataflow/src/framework/direction.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/direction.rs
@@ -1,5 +1,5 @@
 use rustc_middle::mir::{
-    self, BasicBlock, CallReturnPlaces, Location, SwitchTargets, TerminatorEdges, UnwindAction,
+    self, BasicBlock, CallReturnPlaces, Location, SwitchTargets, TerminatorEdges,
 };
 use std::ops::RangeInclusive;
 
@@ -486,10 +486,10 @@ impl Direction for Forward {
                 propagate(target, exit_state);
                 propagate(unwind, exit_state);
             }
-            TerminatorEdges::AssignOnReturn { return_, unwind, place } => {
+            TerminatorEdges::AssignOnReturn { return_, cleanup, place } => {
                 // This must be done *first*, otherwise the unwind path will see the assignments.
-                if let UnwindAction::Cleanup(unwind) = unwind {
-                    propagate(unwind, exit_state);
+                if let Some(cleanup) = cleanup {
+                    propagate(cleanup, exit_state);
                 }
                 if let Some(return_) = return_ {
                     analysis.apply_call_return_effect(exit_state, bb, place);
diff --git a/compiler/rustc_mir_dataflow/src/framework/graphviz.rs b/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
index 1421d9b45..bdddaaebc 100644
--- a/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
@@ -538,7 +538,7 @@ where
 
     fn visit_block_start(
         &mut self,
-        _results: &Results<'tcx, A>,
+        _results: &mut Results<'tcx, A>,
         state: &Self::FlowState,
         _block_data: &mir::BasicBlockData<'tcx>,
         _block: BasicBlock,
@@ -550,7 +550,7 @@ where
 
     fn visit_block_end(
         &mut self,
-        _results: &Results<'tcx, A>,
+        _results: &mut Results<'tcx, A>,
         state: &Self::FlowState,
         _block_data: &mir::BasicBlockData<'tcx>,
         _block: BasicBlock,
@@ -562,7 +562,7 @@ where
 
     fn visit_statement_before_primary_effect(
         &mut self,
-        results: &Results<'tcx, A>,
+        results: &mut Results<'tcx, A>,
         state: &Self::FlowState,
         _statement: &mir::Statement<'tcx>,
         _location: Location,
@@ -575,7 +575,7 @@ where
 
     fn visit_statement_after_primary_effect(
         &mut self,
-        results: &Results<'tcx, A>,
+        results: &mut Results<'tcx, A>,
         state: &Self::FlowState,
         _statement: &mir::Statement<'tcx>,
         _location: Location,
@@ -586,7 +586,7 @@ where
 
     fn visit_terminator_before_primary_effect(
         &mut self,
-        results: &Results<'tcx, A>,
+        results: &mut Results<'tcx, A>,
         state: &Self::FlowState,
         _terminator: &mir::Terminator<'tcx>,
         _location: Location,
@@ -599,7 +599,7 @@ where
 
     fn visit_terminator_after_primary_effect(
         &mut self,
-        results: &Results<'tcx, A>,
+        results: &mut Results<'tcx, A>,
         state: &Self::FlowState,
         _terminator: &mir::Terminator<'tcx>,
         _location: Location,
diff --git a/compiler/rustc_mir_dataflow/src/framework/visitor.rs b/compiler/rustc_mir_dataflow/src/framework/visitor.rs
index 76a729827..3cfa7cc1c 100644
--- a/compiler/rustc_mir_dataflow/src/framework/visitor.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/visitor.rs
@@ -35,7 +35,7 @@ pub trait ResultsVisitor<'mir, 'tcx, R> {
 
     fn visit_block_start(
         &mut self,
-        _results: &R,
+        _results: &mut R,
         _state: &Self::FlowState,
         _block_data: &'mir mir::BasicBlockData<'tcx>,
         _block: BasicBlock,
@@ -46,7 +46,7 @@ pub trait ResultsVisitor<'mir, 'tcx, R> {
     /// its `statement_effect`.
     fn visit_statement_before_primary_effect(
         &mut self,
-        _results: &R,
+        _results: &mut R,
         _state: &Self::FlowState,
         _statement: &'mir mir::Statement<'tcx>,
         _location: Location,
@@ -57,7 +57,7 @@ pub trait ResultsVisitor<'mir, 'tcx, R> {
     /// statement applied to `state`.
     fn visit_statement_after_primary_effect(
         &mut self,
-        _results: &R,
+        _results: &mut R,
         _state: &Self::FlowState,
         _statement: &'mir mir::Statement<'tcx>,
         _location: Location,
@@ -68,7 +68,7 @@ pub trait ResultsVisitor<'mir, 'tcx, R> {
     /// its `terminator_effect`.
     fn visit_terminator_before_primary_effect(
         &mut self,
-        _results: &R,
+        _results: &mut R,
         _state: &Self::FlowState,
         _terminator: &'mir mir::Terminator<'tcx>,
         _location: Location,
@@ -81,7 +81,7 @@ pub trait ResultsVisitor<'mir, 'tcx, R> {
     /// The `call_return_effect` (if one exists) will *not* be applied to `state`.
     fn visit_terminator_after_primary_effect(
         &mut self,
-        _results: &R,
+        _results: &mut R,
         _state: &Self::FlowState,
         _terminator: &'mir mir::Terminator<'tcx>,
         _location: Location,
@@ -90,7 +90,7 @@ pub trait ResultsVisitor<'mir, 'tcx, R> {
 
     fn visit_block_end(
         &mut self,
-        _results: &R,
+        _results: &mut R,
         _state: &Self::FlowState,
         _block_data: &'mir mir::BasicBlockData<'tcx>,
         _block: BasicBlock,
diff --git a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
index 8d7b50796..f6398c8d0 100644
--- a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
@@ -5,7 +5,8 @@ use rustc_middle::mir::*;
 use crate::{AnalysisDomain, GenKill, GenKillAnalysis};
 
 /// A dataflow analysis that tracks whether a pointer or reference could possibly exist that points
-/// to a given local.
+/// to a given local. This analysis ignores fake borrows, so it should not be used by
+/// borrowck.
 ///
 /// At present, this is used as a very limited form of alias analysis. For example,
 /// `MaybeBorrowedLocals` is used to compute which locals are live during a yield expression for
@@ -91,13 +92,17 @@ where
         self.super_rvalue(rvalue, location);
 
         match rvalue {
-            Rvalue::AddressOf(_, borrowed_place) | Rvalue::Ref(_, _, borrowed_place) => {
+            // We ignore fake borrows as these get removed after analysis and shouldn't effect
+            // the layout of generators.
+            Rvalue::AddressOf(_, borrowed_place)
+            | Rvalue::Ref(_, BorrowKind::Mut { .. } | BorrowKind::Shared, borrowed_place) => {
                 if !borrowed_place.is_indirect() {
                     self.trans.gen(borrowed_place.local);
                 }
             }
 
             Rvalue::Cast(..)
+            | Rvalue::Ref(_, BorrowKind::Fake, _)
             | Rvalue::ShallowInitBox(..)
             | Rvalue::Use(..)
             | Rvalue::ThreadLocalRef(..)
@@ -131,7 +136,7 @@ where
                 }
             }
 
-            TerminatorKind::Terminate
+            TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Assert { .. }
             | TerminatorKind::Call { .. }
             | TerminatorKind::FalseEdge { .. }
@@ -139,7 +144,7 @@ where
             | TerminatorKind::GeneratorDrop
             | TerminatorKind::Goto { .. }
             | TerminatorKind::InlineAsm { .. }
-            | TerminatorKind::Resume
+            | TerminatorKind::UnwindResume
             | TerminatorKind::Return
             | TerminatorKind::SwitchInt { .. }
             | TerminatorKind::Unreachable
diff --git a/compiler/rustc_mir_dataflow/src/impls/liveness.rs b/compiler/rustc_mir_dataflow/src/impls/liveness.rs
index 5aa73c7a9..664703795 100644
--- a/compiler/rustc_mir_dataflow/src/impls/liveness.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/liveness.rs
@@ -201,7 +201,7 @@ impl DefUse {
                 | NonMutatingUseContext::Inspect
                 | NonMutatingUseContext::Move
                 | NonMutatingUseContext::PlaceMention
-                | NonMutatingUseContext::ShallowBorrow
+                | NonMutatingUseContext::FakeBorrow
                 | NonMutatingUseContext::SharedBorrow,
             ) => Some(DefUse::Use),
 
diff --git a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
index bea23b7f7..94d6eb67d 100644
--- a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
@@ -291,14 +291,14 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, '_, 'tcx> {
 
             // Nothing to do for these. Match exhaustively so this fails to compile when new
             // variants are added.
-            TerminatorKind::Terminate
+            TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Assert { .. }
             | TerminatorKind::Drop { .. }
             | TerminatorKind::FalseEdge { .. }
             | TerminatorKind::FalseUnwind { .. }
             | TerminatorKind::GeneratorDrop
             | TerminatorKind::Goto { .. }
-            | TerminatorKind::Resume
+            | TerminatorKind::UnwindResume
             | TerminatorKind::Return
             | TerminatorKind::SwitchInt { .. }
             | TerminatorKind::Unreachable => {}
@@ -328,14 +328,14 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, '_, 'tcx> {
             // Nothing to do for these. Match exhaustively so this fails to compile when new
             // variants are added.
             TerminatorKind::Yield { .. }
-            | TerminatorKind::Terminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Assert { .. }
             | TerminatorKind::Drop { .. }
             | TerminatorKind::FalseEdge { .. }
             | TerminatorKind::FalseUnwind { .. }
             | TerminatorKind::GeneratorDrop
             | TerminatorKind::Goto { .. }
-            | TerminatorKind::Resume
+            | TerminatorKind::UnwindResume
             | TerminatorKind::Return
             | TerminatorKind::SwitchInt { .. }
             | TerminatorKind::Unreachable => {}
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs b/compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs
index 7806e8f45..2a7f23ef6 100644
--- a/compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs
+++ b/compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs
@@ -57,6 +57,7 @@ impl<'tcx> Lift for PlaceElem<'tcx> {
                 ProjectionElem::ConstantIndex { offset, min_length, from_end }
             }
             ProjectionElem::Downcast(a, u) => ProjectionElem::Downcast(a, u),
+            ProjectionElem::Subtype(ty) => ProjectionElem::Subtype(ty.lift()),
         }
     }
 }
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
index 5052de991..7a5b3585d 100644
--- a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
+++ b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
@@ -115,44 +115,126 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
             let body = self.builder.body;
             let tcx = self.builder.tcx;
             let place_ty = place_ref.ty(body, tcx).ty;
-            match place_ty.kind() {
-                ty::Ref(..) | ty::RawPtr(..) => {
-                    return Err(MoveError::cannot_move_out_of(
-                        self.loc,
-                        BorrowedContent { target_place: place_ref.project_deeper(&[elem], tcx) },
-                    ));
-                }
-                ty::Adt(adt, _) if adt.has_dtor(tcx) && !adt.is_box() => {
-                    return Err(MoveError::cannot_move_out_of(
-                        self.loc,
-                        InteriorOfTypeWithDestructor { container_ty: place_ty },
-                    ));
-                }
-                ty::Adt(adt, _) if adt.is_union() => {
-                    union_path.get_or_insert(base);
-                }
-                ty::Slice(_) => {
-                    return Err(MoveError::cannot_move_out_of(
-                        self.loc,
-                        InteriorOfSliceOrArray {
-                            ty: place_ty,
-                            is_index: matches!(elem, ProjectionElem::Index(..)),
-                        },
-                    ));
+            match elem {
+                ProjectionElem::Deref => match place_ty.kind() {
+                    ty::Ref(..) | ty::RawPtr(..) => {
+                        return Err(MoveError::cannot_move_out_of(
+                            self.loc,
+                            BorrowedContent {
+                                target_place: place_ref.project_deeper(&[elem], tcx),
+                            },
+                        ));
+                    }
+                    ty::Adt(adt, _) => {
+                        if !adt.is_box() {
+                            bug!("Adt should be a box type when Place is deref");
+                        }
+                    }
+                    ty::Bool
+                    | ty::Char
+                    | ty::Int(_)
+                    | ty::Uint(_)
+                    | ty::Float(_)
+                    | ty::Foreign(_)
+                    | ty::Str
+                    | ty::Array(_, _)
+                    | ty::Slice(_)
+                    | ty::FnDef(_, _)
+                    | ty::FnPtr(_)
+                    | ty::Dynamic(_, _, _)
+                    | ty::Closure(_, _)
+                    | ty::Generator(_, _, _)
+                    | ty::GeneratorWitness(..)
+                    | ty::Never
+                    | ty::Tuple(_)
+                    | ty::Alias(_, _)
+                    | ty::Param(_)
+                    | ty::Bound(_, _)
+                    | ty::Infer(_)
+                    | ty::Error(_)
+                    | ty::Placeholder(_) => {
+                        bug!("When Place is Deref it's type shouldn't be {place_ty:#?}")
+                    }
+                },
+                ProjectionElem::Field(_, _) => match place_ty.kind() {
+                    ty::Adt(adt, _) => {
+                        if adt.has_dtor(tcx) {
+                            return Err(MoveError::cannot_move_out_of(
+                                self.loc,
+                                InteriorOfTypeWithDestructor { container_ty: place_ty },
+                            ));
+                        }
+                        if adt.is_union() {
+                            union_path.get_or_insert(base);
+                        }
+                    }
+                    ty::Closure(_, _) | ty::Generator(_, _, _) | ty::Tuple(_) => (),
+                    ty::Bool
+                    | ty::Char
+                    | ty::Int(_)
+                    | ty::Uint(_)
+                    | ty::Float(_)
+                    | ty::Foreign(_)
+                    | ty::Str
+                    | ty::Array(_, _)
+                    | ty::Slice(_)
+                    | ty::RawPtr(_)
+                    | ty::Ref(_, _, _)
+                    | ty::FnDef(_, _)
+                    | ty::FnPtr(_)
+                    | ty::Dynamic(_, _, _)
+                    | ty::GeneratorWitness(..)
+                    | ty::Never
+                    | ty::Alias(_, _)
+                    | ty::Param(_)
+                    | ty::Bound(_, _)
+                    | ty::Infer(_)
+                    | ty::Error(_)
+                    | ty::Placeholder(_) => bug!(
+                        "When Place contains ProjectionElem::Field it's type shouldn't be {place_ty:#?}"
+                    ),
+                },
+                ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {
+                    match place_ty.kind() {
+                        ty::Slice(_) => {
+                            return Err(MoveError::cannot_move_out_of(
+                                self.loc,
+                                InteriorOfSliceOrArray {
+                                    ty: place_ty,
+                                    is_index: matches!(elem, ProjectionElem::Index(..)),
+                                },
+                            ));
+                        }
+                        ty::Array(_, _) => (),
+                        _ => bug!("Unexpected type {:#?}", place_ty.is_array()),
+                    }
                 }
-
-                ty::Array(..) => {
-                    if let ProjectionElem::Index(..) = elem {
+                ProjectionElem::Index(_) => match place_ty.kind() {
+                    ty::Array(..) => {
                         return Err(MoveError::cannot_move_out_of(
                             self.loc,
                             InteriorOfSliceOrArray { ty: place_ty, is_index: true },
                         ));
                     }
-                }
-
-                _ => {}
-            };
-
+                    ty::Slice(_) => {
+                        return Err(MoveError::cannot_move_out_of(
+                            self.loc,
+                            InteriorOfSliceOrArray {
+                                ty: place_ty,
+                                is_index: matches!(elem, ProjectionElem::Index(..)),
+                            },
+                        ));
+                    }
+                    _ => bug!("Unexpected type {place_ty:#?}"),
+                },
+                // `OpaqueCast`:Only transmutes the type, so no moves there.
+                // `Downcast`  :Only changes information about a `Place` without moving.
+                // `Subtype`   :Only transmutes the type, so moves.
+                // So it's safe to skip these.
+                ProjectionElem::OpaqueCast(_)
+                | ProjectionElem::Subtype(_)
+                | ProjectionElem::Downcast(_, _) => (),
+            }
             if union_path.is_none() {
                 // inlined from add_move_path because of a borrowck conflict with the iterator
                 base =
@@ -370,8 +452,8 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
             // this that could possibly access the return place, this doesn't
             // need recording.
             | TerminatorKind::Return
-            | TerminatorKind::Resume
-            | TerminatorKind::Terminate
+            | TerminatorKind::UnwindResume
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::GeneratorDrop
             | TerminatorKind::Unreachable
             | TerminatorKind::Drop { .. } => {}
diff --git a/compiler/rustc_mir_dataflow/src/rustc_peek.rs b/compiler/rustc_mir_dataflow/src/rustc_peek.rs
index 775c522b4..1ebb59b3a 100644
--- a/compiler/rustc_mir_dataflow/src/rustc_peek.rs
+++ b/compiler/rustc_mir_dataflow/src/rustc_peek.rs
@@ -190,7 +190,7 @@ impl PeekCall {
         if let mir::TerminatorKind::Call { func: Operand::Constant(func), args, .. } =
             &terminator.kind
         {
-            if let ty::FnDef(def_id, fn_args) = *func.literal.ty().kind() {
+            if let ty::FnDef(def_id, fn_args) = *func.const_.ty().kind() {
                 let name = tcx.item_name(def_id);
                 if !tcx.is_intrinsic(def_id) || name != sym::rustc_peek {
                     return None;
diff --git a/compiler/rustc_mir_dataflow/src/value_analysis.rs b/compiler/rustc_mir_dataflow/src/value_analysis.rs
index 766e0257e..83766f311 100644
--- a/compiler/rustc_mir_dataflow/src/value_analysis.rs
+++ b/compiler/rustc_mir_dataflow/src/value_analysis.rs
@@ -225,7 +225,7 @@ pub trait ValueAnalysis<'tcx> {
 
     fn handle_constant(
         &self,
-        constant: &Constant<'tcx>,
+        constant: &ConstOperand<'tcx>,
         state: &mut State<Self::Value>,
     ) -> Self::Value {
         self.super_constant(constant, state)
@@ -233,7 +233,7 @@ pub trait ValueAnalysis<'tcx> {
 
     fn super_constant(
         &self,
-        _constant: &Constant<'tcx>,
+        _constant: &ConstOperand<'tcx>,
         _state: &mut State<Self::Value>,
     ) -> Self::Value {
         Self::Value::TOP
@@ -269,8 +269,8 @@ pub trait ValueAnalysis<'tcx> {
                 return self.handle_switch_int(discr, targets, state);
             }
             TerminatorKind::Goto { .. }
-            | TerminatorKind::Resume
-            | TerminatorKind::Terminate
+            | TerminatorKind::UnwindResume
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::Unreachable
             | TerminatorKind::Assert { .. }
@@ -532,7 +532,7 @@ impl<V: Clone + HasTop + HasBottom> State<V> {
     /// places that are non-overlapping or identical.
     ///
     /// The target place must have been flooded before calling this method.
-    fn insert_place_idx(&mut self, target: PlaceIndex, source: PlaceIndex, map: &Map) {
+    pub fn insert_place_idx(&mut self, target: PlaceIndex, source: PlaceIndex, map: &Map) {
         let StateData::Reachable(values) = &mut self.0 else { return };
 
         // If both places are tracked, we copy the value to the target.
@@ -581,6 +581,14 @@ impl<V: Clone + HasTop + HasBottom> State<V> {
         }
     }
 
+    /// Retrieve the value stored for a place, or ⊤ if it is not tracked.
+    pub fn get_len(&self, place: PlaceRef<'_>, map: &Map) -> V {
+        match map.find_len(place) {
+            Some(place) => self.get_idx(place, map),
+            None => V::TOP,
+        }
+    }
+
     /// Retrieve the value stored for a place index, or ⊤ if it is not tracked.
     pub fn get_idx(&self, place: PlaceIndex, map: &Map) -> V {
         match &self.0 {
@@ -626,45 +634,36 @@ pub struct Map {
 }
 
 impl Map {
-    fn new() -> Self {
-        Self {
+    /// Returns a map that only tracks places whose type has scalar layout.
+    ///
+    /// This is currently the only way to create a [`Map`]. The way in which the tracked places are
+    /// chosen is an implementation detail and may not be relied upon (other than that their type
+    /// are scalars).
+    pub fn new<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, value_limit: Option<usize>) -> Self {
+        let mut map = Self {
             locals: IndexVec::new(),
             projections: FxHashMap::default(),
             places: IndexVec::new(),
             value_count: 0,
             inner_values: IndexVec::new(),
             inner_values_buffer: Vec::new(),
-        }
-    }
-
-    /// Returns a map that only tracks places whose type passes the filter.
-    ///
-    /// This is currently the only way to create a [`Map`]. The way in which the tracked places are
-    /// chosen is an implementation detail and may not be relied upon (other than that their type
-    /// passes the filter).
-    pub fn from_filter<'tcx>(
-        tcx: TyCtxt<'tcx>,
-        body: &Body<'tcx>,
-        filter: impl Fn(Ty<'tcx>) -> bool,
-        value_limit: Option<usize>,
-    ) -> Self {
-        let mut map = Self::new();
+        };
         let exclude = excluded_locals(body);
-        map.register_with_filter(tcx, body, filter, exclude, value_limit);
+        map.register(tcx, body, exclude, value_limit);
         debug!("registered {} places ({} nodes in total)", map.value_count, map.places.len());
         map
     }
 
-    /// Register all non-excluded places that pass the filter.
-    fn register_with_filter<'tcx>(
+    /// Register all non-excluded places that have scalar layout.
+    fn register<'tcx>(
         &mut self,
         tcx: TyCtxt<'tcx>,
         body: &Body<'tcx>,
-        filter: impl Fn(Ty<'tcx>) -> bool,
         exclude: BitSet<Local>,
         value_limit: Option<usize>,
     ) {
         let mut worklist = VecDeque::with_capacity(value_limit.unwrap_or(body.local_decls.len()));
+        let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
 
         // Start by constructing the places for each bare local.
         self.locals = IndexVec::from_elem(None, &body.local_decls);
@@ -679,7 +678,7 @@ impl Map {
             self.locals[local] = Some(place);
 
             // And push the eventual children places to the worklist.
-            self.register_children(tcx, place, decl.ty, &filter, &mut worklist);
+            self.register_children(tcx, param_env, place, decl.ty, &mut worklist);
         }
 
         // `place.elem1.elem2` with type `ty`.
@@ -702,7 +701,7 @@ impl Map {
             }
 
             // And push the eventual children places to the worklist.
-            self.register_children(tcx, place, ty, &filter, &mut worklist);
+            self.register_children(tcx, param_env, place, ty, &mut worklist);
         }
 
         // Pre-compute the tree of ValueIndex nested in each PlaceIndex.
@@ -732,42 +731,54 @@ impl Map {
     fn register_children<'tcx>(
         &mut self,
         tcx: TyCtxt<'tcx>,
+        param_env: ty::ParamEnv<'tcx>,
         place: PlaceIndex,
         ty: Ty<'tcx>,
-        filter: &impl Fn(Ty<'tcx>) -> bool,
         worklist: &mut VecDeque<(PlaceIndex, Option<TrackElem>, TrackElem, Ty<'tcx>)>,
     ) {
         // Allocate a value slot if it doesn't have one, and the user requested one.
-        if self.places[place].value_index.is_none() && filter(ty) {
+        assert!(self.places[place].value_index.is_none());
+        if tcx.layout_of(param_env.and(ty)).map_or(false, |layout| layout.abi.is_scalar()) {
             self.places[place].value_index = Some(self.value_count.into());
             self.value_count += 1;
         }
 
         // For enums, directly create the `Discriminant`, as that's their main use.
         if ty.is_enum() {
-            let discr_ty = ty.discriminant_ty(tcx);
-            if filter(discr_ty) {
-                let discr = *self
-                    .projections
-                    .entry((place, TrackElem::Discriminant))
-                    .or_insert_with(|| {
-                        // Prepend new child to the linked list.
-                        let next = self.places.push(PlaceInfo::new(Some(TrackElem::Discriminant)));
-                        self.places[next].next_sibling = self.places[place].first_child;
-                        self.places[place].first_child = Some(next);
-                        next
-                    });
-
-                // Allocate a value slot if it doesn't have one.
-                if self.places[discr].value_index.is_none() {
-                    self.places[discr].value_index = Some(self.value_count.into());
-                    self.value_count += 1;
-                }
-            }
+            // Prepend new child to the linked list.
+            let discr = self.places.push(PlaceInfo::new(Some(TrackElem::Discriminant)));
+            self.places[discr].next_sibling = self.places[place].first_child;
+            self.places[place].first_child = Some(discr);
+            let old = self.projections.insert((place, TrackElem::Discriminant), discr);
+            assert!(old.is_none());
+
+            // Allocate a value slot since it doesn't have one.
+            assert!(self.places[discr].value_index.is_none());
+            self.places[discr].value_index = Some(self.value_count.into());
+            self.value_count += 1;
+        }
+
+        if let ty::Ref(_, ref_ty, _) | ty::RawPtr(ty::TypeAndMut { ty: ref_ty, .. }) = ty.kind()
+            && let ty::Slice(..) = ref_ty.kind()
+        {
+            assert!(self.places[place].value_index.is_none(), "slices are not scalars");
+
+            // Prepend new child to the linked list.
+            let len = self.places.push(PlaceInfo::new(Some(TrackElem::DerefLen)));
+            self.places[len].next_sibling = self.places[place].first_child;
+            self.places[place].first_child = Some(len);
+
+            let old = self.projections.insert((place, TrackElem::DerefLen), len);
+            assert!(old.is_none());
+
+            // Allocate a value slot since it doesn't have one.
+            assert!( self.places[len].value_index.is_none() );
+            self.places[len].value_index = Some(self.value_count.into());
+            self.value_count += 1;
         }
 
         // Recurse with all fields of this place.
-        iter_fields(ty, tcx, ty::ParamEnv::reveal_all(), |variant, field, ty| {
+        iter_fields(ty, tcx, param_env, |variant, field, ty| {
             worklist.push_back((
                 place,
                 variant.map(TrackElem::Variant),
@@ -834,6 +845,11 @@ impl Map {
         self.find_extra(place, [TrackElem::Discriminant])
     }
 
+    /// Locates the given place and applies `DerefLen`, if it exists in the tree.
+    pub fn find_len(&self, place: PlaceRef<'_>) -> Option<PlaceIndex> {
+        self.find_extra(place, [TrackElem::DerefLen])
+    }
+
     /// Iterate over all direct children.
     pub fn children(&self, parent: PlaceIndex) -> impl Iterator<Item = PlaceIndex> + '_ {
         Children::new(self, parent)
@@ -914,6 +930,31 @@ impl Map {
             f(v)
         }
     }
+
+    /// Invoke a function on each value in the given place and all descendants.
+    pub fn for_each_projection_value<O>(
+        &self,
+        root: PlaceIndex,
+        value: O,
+        project: &mut impl FnMut(TrackElem, &O) -> Option<O>,
+        f: &mut impl FnMut(PlaceIndex, &O),
+    ) {
+        // Fast path is there is nothing to do.
+        if self.inner_values[root].is_empty() {
+            return;
+        }
+
+        if self.places[root].value_index.is_some() {
+            f(root, &value)
+        }
+
+        for child in self.children(root) {
+            let elem = self.places[child].proj_elem.unwrap();
+            if let Some(value) = project(elem, &value) {
+                self.for_each_projection_value(child, value, project, f);
+            }
+        }
+    }
 }
 
 /// This is the information tracked for every [`PlaceIndex`] and is stored by [`Map`].
@@ -985,6 +1026,8 @@ pub enum TrackElem {
     Field(FieldIdx),
     Variant(VariantIdx),
     Discriminant,
+    // Length of a slice.
+    DerefLen,
 }
 
 impl<V, T> TryFrom<ProjectionElem<V, T>> for TrackElem {
@@ -1124,6 +1167,9 @@ fn debug_with_context_rec<V: Debug + Eq>(
                     format!("{}.{}", place_str, field.index())
                 }
             }
+            TrackElem::DerefLen => {
+                format!("Len(*{})", place_str)
+            }
         };
         debug_with_context_rec(child, &child_place_str, new, old, map, f)?;
     }