Auto merge of #134330 - scottmcm:no-more-rvalue-len, r=matthewjasper

Delete `Rvalue::Len` 🎉

Everything's moved to `PtrMetadata`, so we can get rid of the `Len` variant now.

~~Depends on #134326, so draft until that lands~~ Ready!

r? mir

Author: bors

compiler/rustc_borrowck/src/lib.rs

@@ -820,7 +820,6 @@ use self::ReadOrWrite::{Activation, Read, Reservation, Write};
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 enum ArtificialField {
-    ArrayLength,
     FakeBorrow,
 }
 
@@ -1268,16 +1267,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
                 );
             }
 
-            &(Rvalue::Len(place) | Rvalue::Discriminant(place)) => {
-                let af = match *rvalue {
-                    Rvalue::Len(..) => Some(ArtificialField::ArrayLength),
-                    Rvalue::Discriminant(..) => None,
-                    _ => unreachable!(),
-                };
+            &Rvalue::Discriminant(place) => {
                 self.access_place(
                     location,
                     (place, span),
-                    (Shallow(af), Read(ReadKind::Copy)),
+                    (Shallow(None), Read(ReadKind::Copy)),
                     LocalMutationIsAllowed::No,
                     state,
                 );

compiler/rustc_borrowck/src/places_conflict.rs

@@ -203,8 +203,7 @@ fn place_components_conflict<'tcx>(
             let base_ty = base.ty(body, tcx).ty;
 
             match (elem, base_ty.kind(), access) {
-                (_, _, Shallow(Some(ArtificialField::ArrayLength)))
-                | (_, _, Shallow(Some(ArtificialField::FakeBorrow))) => {
+                (_, _, Shallow(Some(ArtificialField::FakeBorrow))) => {
                     // The array length is like additional fields on the
                     // type; it does not overlap any existing data there.
                     // Furthermore, if cannot actually be a prefix of any

compiler/rustc_borrowck/src/polonius/legacy/loan_invalidations.rs

@@ -299,16 +299,11 @@ impl<'a, 'tcx> LoanInvalidationsGenerator<'a, 'tcx> {
                 self.consume_operand(location, op);
             }
 
-            &(Rvalue::Len(place) | Rvalue::Discriminant(place)) => {
-                let af = match rvalue {
-                    Rvalue::Len(..) => Some(ArtificialField::ArrayLength),
-                    Rvalue::Discriminant(..) => None,
-                    _ => unreachable!(),
-                };
+            &Rvalue::Discriminant(place) => {
                 self.access_place(
                     location,
                     place,
-                    (Shallow(af), Read(ReadKind::Copy)),
+                    (Shallow(None), Read(ReadKind::Copy)),
                     LocalMutationIsAllowed::No,
                 );
             }

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -2427,7 +2427,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
 
             Rvalue::RawPtr(..)
             | Rvalue::ThreadLocalRef(..)
-            | Rvalue::Len(..)
             | Rvalue::Discriminant(..)
             | Rvalue::NullaryOp(NullOp::OffsetOf(..), _) => {}
         }
@@ -2443,7 +2442,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             | Rvalue::Repeat(..)
             | Rvalue::Ref(..)
             | Rvalue::RawPtr(..)
-            | Rvalue::Len(..)
             | Rvalue::Cast(..)
             | Rvalue::ShallowInitBox(..)
             | Rvalue::BinaryOp(..)

compiler/rustc_codegen_cranelift/src/base.rs

@@ -828,12 +828,6 @@ fn codegen_stmt<'tcx>(
                         fx.bcx.ins().nop();
                     }
                 }
-                Rvalue::Len(place) => {
-                    let place = codegen_place(fx, place);
-                    let usize_layout = fx.layout_of(fx.tcx.types.usize);
-                    let len = codegen_array_len(fx, place);
-                    lval.write_cvalue(fx, CValue::by_val(len, usize_layout));
-                }
                 Rvalue::ShallowInitBox(ref operand, content_ty) => {
                     let content_ty = fx.monomorphize(content_ty);
                     let box_layout = fx.layout_of(Ty::new_box(fx.tcx, content_ty));

compiler/rustc_codegen_ssa/src/mir/rvalue.rs

@@ -10,9 +10,9 @@ use rustc_session::config::OptLevel;
 use rustc_span::{DUMMY_SP, Span};
 use tracing::{debug, instrument};
 
+use super::FunctionCx;
 use super::operand::{OperandRef, OperandValue};
 use super::place::PlaceRef;
-use super::{FunctionCx, LocalRef};
 use crate::common::IntPredicate;
 use crate::traits::*;
 use crate::{MemFlags, base};
@@ -593,14 +593,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 self.codegen_place_to_pointer(bx, place, mk_ptr)
             }
 
-            mir::Rvalue::Len(place) => {
-                let size = self.evaluate_array_len(bx, place);
-                OperandRef {
-                    val: OperandValue::Immediate(size),
-                    layout: bx.cx().layout_of(bx.tcx().types.usize),
-                }
-            }
-
             mir::Rvalue::BinaryOp(op_with_overflow, box (ref lhs, ref rhs))
                 if let Some(op) = op_with_overflow.overflowing_to_wrapping() =>
             {
@@ -800,24 +792,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         }
     }
 
-    fn evaluate_array_len(&mut self, bx: &mut Bx, place: mir::Place<'tcx>) -> Bx::Value {
-        // ZST are passed as operands and require special handling
-        // because codegen_place() panics if Local is operand.
-        if let Some(index) = place.as_local() {
-            if let LocalRef::Operand(op) = self.locals[index] {
-                if let ty::Array(_, n) = op.layout.ty.kind() {
-                    let n = n
-                        .try_to_target_usize(bx.tcx())
-                        .expect("expected monomorphic const in codegen");
-                    return bx.cx().const_usize(n);
-                }
-            }
-        }
-        // use common size calculation for non zero-sized types
-        let cg_value = self.codegen_place(bx, place.as_ref());
-        cg_value.len(bx.cx())
-    }
-
     /// Codegen an `Rvalue::RawPtr` or `Rvalue::Ref`
     fn codegen_place_to_pointer(
         &mut self,
@@ -1089,7 +1063,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             mir::Rvalue::Ref(..) |
             mir::Rvalue::CopyForDeref(..) |
             mir::Rvalue::RawPtr(..) |
-            mir::Rvalue::Len(..) |
             mir::Rvalue::Cast(..) | // (*)
             mir::Rvalue::ShallowInitBox(..) | // (*)
             mir::Rvalue::BinaryOp(..) |

compiler/rustc_const_eval/src/check_consts/check.rs

@@ -488,8 +488,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
             Rvalue::Use(_)
             | Rvalue::CopyForDeref(..)
             | Rvalue::Repeat(..)
-            | Rvalue::Discriminant(..)
-            | Rvalue::Len(_) => {}
+            | Rvalue::Discriminant(..) => {}
 
             Rvalue::Aggregate(kind, ..) => {
                 if let AggregateKind::Coroutine(def_id, ..) = kind.as_ref()

compiler/rustc_const_eval/src/check_consts/qualifs.rs

@@ -230,9 +230,7 @@ where
             Q::in_any_value_of_ty(cx, rvalue.ty(cx.body, cx.tcx))
         }
 
-        Rvalue::Discriminant(place) | Rvalue::Len(place) => {
-            in_place::<Q, _>(cx, in_local, place.as_ref())
-        }
+        Rvalue::Discriminant(place) => in_place::<Q, _>(cx, in_local, place.as_ref()),
 
         Rvalue::CopyForDeref(place) => in_place::<Q, _>(cx, in_local, place.as_ref()),
 

compiler/rustc_const_eval/src/check_consts/resolver.rs

@@ -197,7 +197,6 @@ where
             | mir::Rvalue::CopyForDeref(..)
             | mir::Rvalue::ThreadLocalRef(..)
             | mir::Rvalue::Repeat(..)
-            | mir::Rvalue::Len(..)
             | mir::Rvalue::BinaryOp(..)
             | mir::Rvalue::NullaryOp(..)
             | mir::Rvalue::UnaryOp(..)

compiler/rustc_const_eval/src/interpret/step.rs

@@ -15,7 +15,7 @@ use tracing::{info, instrument, trace};
 
 use super::{
     FnArg, FnVal, ImmTy, Immediate, InterpCx, InterpResult, Machine, MemPlaceMeta, PlaceTy,
-    Projectable, Scalar, interp_ok, throw_ub,
+    Projectable, interp_ok, throw_ub,
 };
 use crate::util;
 
@@ -218,12 +218,6 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 self.write_repeat(operand, &dest)?;
             }
 
-            Len(place) => {
-                let src = self.eval_place(place)?;
-                let len = src.len(self)?;
-                self.write_scalar(Scalar::from_target_usize(len, self), &dest)?;
-            }
-
             Ref(_, borrow_kind, place) => {
                 let src = self.eval_place(place)?;
                 let place = self.force_allocation(&src)?;

compiler/rustc_middle/src/mir/pretty.rs

@@ -1068,7 +1068,6 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                 pretty_print_const(b, fmt, false)?;
                 write!(fmt, "]")
             }
-            Len(ref a) => write!(fmt, "Len({a:?})"),
             Cast(ref kind, ref place, ref ty) => {
                 with_no_trimmed_paths!(write!(fmt, "{place:?} as {ty} ({kind:?})"))
             }

compiler/rustc_middle/src/mir/statement.rs

@@ -424,7 +424,6 @@ impl<'tcx> Rvalue<'tcx> {
             | Rvalue::Ref(_, _, _)
             | Rvalue::ThreadLocalRef(_)
             | Rvalue::RawPtr(_, _)
-            | Rvalue::Len(_)
             | Rvalue::Cast(
                 CastKind::IntToInt
                 | CastKind::FloatToInt

compiler/rustc_middle/src/mir/syntax.rs

@@ -1351,16 +1351,6 @@ pub enum Rvalue<'tcx> {
     /// model.
     RawPtr(Mutability, Place<'tcx>),
 
-    /// Yields the length of the place, as a `usize`.
-    ///
-    /// If the type of the place is an array, this is the array length. For slices (`[T]`, not
-    /// `&[T]`) this accesses the place's metadata to determine the length. This rvalue is
-    /// ill-formed for places of other types.
-    ///
-    /// This cannot be a `UnOp(PtrMetadata, _)` because that expects a value, and we only
-    /// have a place, and `UnOp(PtrMetadata, RawPtr(place))` is not a thing.
-    Len(Place<'tcx>),
-
     /// Performs essentially all of the casts that can be performed via `as`.
     ///
     /// This allows for casts from/to a variety of types.

compiler/rustc_middle/src/mir/tcx.rs

@@ -175,7 +175,6 @@ impl<'tcx> Rvalue<'tcx> {
                 let place_ty = place.ty(local_decls, tcx).ty;
                 Ty::new_ptr(tcx, place_ty, mutability)
             }
-            Rvalue::Len(..) => tcx.types.usize,
             Rvalue::Cast(.., ty) => ty,
             Rvalue::BinaryOp(op, box (ref lhs, ref rhs)) => {
                 let lhs_ty = lhs.ty(local_decls, tcx);

compiler/rustc_middle/src/mir/visit.rs

@@ -695,14 +695,6 @@ macro_rules! make_mir_visitor {
                         self.visit_place(path, ctx, location);
                     }
 
-                    Rvalue::Len(path) => {
-                        self.visit_place(
-                            path,
-                            PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect),
-                            location
-                        );
-                    }
-
                     Rvalue::Cast(_cast_kind, operand, ty) => {
                         self.visit_operand(operand, location);
                         self.visit_ty($(& $mutability)? *ty, TyContext::Location(location));

compiler/rustc_mir_build/src/builder/custom/parse/instruction.rs

@@ -246,7 +246,6 @@ impl<'a, 'tcx> ParseCtxt<'a, 'tcx> {
                 let offset = self.parse_operand(args[1])?;
                 Ok(Rvalue::BinaryOp(BinOp::Offset, Box::new((ptr, offset))))
             },
-            @call(mir_len, args) => Ok(Rvalue::Len(self.parse_place(args[0])?)),
             @call(mir_ptr_metadata, args) => Ok(Rvalue::UnaryOp(UnOp::PtrMetadata, self.parse_operand(args[0])?)),
             @call(mir_copy_for_deref, args) => Ok(Rvalue::CopyForDeref(self.parse_place(args[0])?)),
             ExprKind::Borrow { borrow_kind, arg } => Ok(

compiler/rustc_mir_build/src/builder/expr/as_place.rs

@@ -635,7 +635,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     ///
     /// For arrays it'll be `Operand::Constant` with the actual length;
     /// For slices it'll be `Operand::Move` of a local using `PtrMetadata`.
-    fn len_of_slice_or_array(
+    pub(in crate::builder) fn len_of_slice_or_array(
         &mut self,
         block: BasicBlock,
         place: Place<'tcx>,

compiler/rustc_mir_build/src/builder/matches/test.rs

@@ -243,11 +243,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             }
 
             TestKind::Len { len, op } => {
-                let usize_ty = self.tcx.types.usize;
-                let actual = self.temp(usize_ty, test.span);
-
                 // actual = len(place)
-                self.cfg.push_assign(block, source_info, actual, Rvalue::Len(place));
+                let actual = self.len_of_slice_or_array(block, place, test.span, source_info);
 
                 // expected = <N>
                 let expected = self.push_usize(block, source_info, len);
@@ -262,7 +259,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     fail_block,
                     source_info,
                     op,
-                    Operand::Move(actual),
+                    actual,
                     Operand::Move(expected),
                 );
             }

compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs

@@ -91,7 +91,6 @@ where
             | Rvalue::Use(..)
             | Rvalue::ThreadLocalRef(..)
             | Rvalue::Repeat(..)
-            | Rvalue::Len(..)
             | Rvalue::BinaryOp(..)
             | Rvalue::NullaryOp(..)
             | Rvalue::UnaryOp(..)

compiler/rustc_mir_dataflow/src/move_paths/builder.rs

@@ -411,7 +411,6 @@ impl<'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> MoveDataBuilder<'a, 'tcx, F> {
             Rvalue::Ref(..)
             | Rvalue::RawPtr(..)
             | Rvalue::Discriminant(..)
-            | Rvalue::Len(..)
             | Rvalue::NullaryOp(
                 NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(..) | NullOp::UbChecks,
                 _,

compiler/rustc_mir_transform/src/dataflow_const_prop.rs

@@ -408,18 +408,6 @@ impl<'a, 'tcx> ConstAnalysis<'a, 'tcx> {
         state: &mut State<FlatSet<Scalar>>,
     ) -> ValueOrPlace<FlatSet<Scalar>> {
         let val = match rvalue {
-            Rvalue::Len(place) => {
-                let place_ty = place.ty(self.local_decls, self.tcx);
-                if let ty::Array(_, len) = place_ty.ty.kind() {
-                    Const::Ty(self.tcx.types.usize, *len)
-                        .try_eval_scalar(self.tcx, self.typing_env)
-                        .map_or(FlatSet::Top, FlatSet::Elem)
-                } else if let [ProjectionElem::Deref] = place.projection[..] {
-                    state.get_len(place.local.into(), &self.map)
-                } else {
-                    FlatSet::Top
-                }
-            }
             Rvalue::Cast(CastKind::IntToInt | CastKind::IntToFloat, operand, ty) => {
                 let Ok(layout) = self.tcx.layout_of(self.typing_env.as_query_input(*ty)) else {
                     return ValueOrPlace::Value(FlatSet::Top);

compiler/rustc_mir_transform/src/dest_prop.rs

@@ -574,7 +574,6 @@ impl WriteInfo {
                     | Rvalue::NullaryOp(_, _)
                     | Rvalue::Ref(_, _, _)
                     | Rvalue::RawPtr(_, _)
-                    | Rvalue::Len(_)
                     | Rvalue::Discriminant(_)
                     | Rvalue::CopyForDeref(_) => {}
                 }

compiler/rustc_mir_transform/src/gvn.rs

@@ -223,8 +223,6 @@ enum Value<'tcx> {
     Projection(VnIndex, ProjectionElem<VnIndex, Ty<'tcx>>),
     /// Discriminant of the given value.
     Discriminant(VnIndex),
-    /// Length of an array or slice.
-    Len(VnIndex),
 
     // Operations.
     NullaryOp(NullOp<'tcx>, Ty<'tcx>),
@@ -513,13 +511,6 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
                     self.ecx.discriminant_for_variant(base.layout.ty, variant).discard_err()?;
                 discr_value.into()
             }
-            Len(slice) => {
-                let slice = self.evaluated[slice].as_ref()?;
-                let usize_layout = self.ecx.layout_of(self.tcx.types.usize).unwrap();
-                let len = slice.len(&self.ecx).discard_err()?;
-                let imm = ImmTy::from_uint(len, usize_layout);
-                imm.into()
-            }
             NullaryOp(null_op, ty) => {
                 let layout = self.ecx.layout_of(ty).ok()?;
                 if let NullOp::SizeOf | NullOp::AlignOf = null_op
@@ -863,7 +854,6 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
             }
 
             // Operations.
-            Rvalue::Len(ref mut place) => return self.simplify_len(place, location),
             Rvalue::Cast(ref mut kind, ref mut value, to) => {
                 return self.simplify_cast(kind, value, to, location);
             }
@@ -1433,47 +1423,6 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
         Some(self.insert(Value::Cast { kind: *kind, value, from, to }))
     }
 
-    fn simplify_len(&mut self, place: &mut Place<'tcx>, location: Location) -> Option<VnIndex> {
-        // Trivial case: we are fetching a statically known length.
-        let place_ty = place.ty(self.local_decls, self.tcx).ty;
-        if let ty::Array(_, len) = place_ty.kind() {
-            return self.insert_constant(Const::from_ty_const(
-                *len,
-                self.tcx.types.usize,
-                self.tcx,
-            ));
-        }
-
-        let mut inner = self.simplify_place_value(place, location)?;
-
-        // The length information is stored in the wide pointer.
-        // Reborrowing copies length information from one pointer to the other.
-        while let Value::Address { place: borrowed, .. } = self.get(inner)
-            && let [PlaceElem::Deref] = borrowed.projection[..]
-            && let Some(borrowed) = self.locals[borrowed.local]
-        {
-            inner = borrowed;
-        }
-
-        // We have an unsizing cast, which assigns the length to wide pointer metadata.
-        if let Value::Cast { kind, from, to, .. } = self.get(inner)
-            && let CastKind::PointerCoercion(ty::adjustment::PointerCoercion::Unsize, _) = kind
-            && let Some(from) = from.builtin_deref(true)
-            && let ty::Array(_, len) = from.kind()
-            && let Some(to) = to.builtin_deref(true)
-            && let ty::Slice(..) = to.kind()
-        {
-            return self.insert_constant(Const::from_ty_const(
-                *len,
-                self.tcx.types.usize,
-                self.tcx,
-            ));
-        }
-
-        // Fallback: a symbolic `Len`.
-        Some(self.insert(Value::Len(inner)))
-    }
-
     fn pointers_have_same_metadata(&self, left_ptr_ty: Ty<'tcx>, right_ptr_ty: Ty<'tcx>) -> bool {
         let left_meta_ty = left_ptr_ty.pointee_metadata_ty_or_projection(self.tcx);
         let right_meta_ty = right_ptr_ty.pointee_metadata_ty_or_projection(self.tcx);

compiler/rustc_mir_transform/src/known_panics_lint.rs

@@ -440,7 +440,6 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             | Rvalue::Use(..)
             | Rvalue::CopyForDeref(..)
             | Rvalue::Repeat(..)
-            | Rvalue::Len(..)
             | Rvalue::Cast(..)
             | Rvalue::ShallowInitBox(..)
             | Rvalue::Discriminant(..)
@@ -600,20 +599,6 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                 return None;
             }
 
-            Len(place) => {
-                let len = if let ty::Array(_, n) = place.ty(self.local_decls(), self.tcx).ty.kind()
-                {
-                    n.try_to_target_usize(self.tcx)?
-                } else {
-                    match self.get_const(place)? {
-                        Value::Immediate(src) => src.len(&self.ecx).discard_err()?,
-                        Value::Aggregate { fields, .. } => fields.len() as u64,
-                        Value::Uninit => return None,
-                    }
-                };
-                ImmTy::from_scalar(Scalar::from_target_usize(len, self), layout).into()
-            }
-
             Ref(..) | RawPtr(..) => return None,
 
             NullaryOp(ref null_op, ty) => {

compiler/rustc_mir_transform/src/promote_consts.rs

@@ -430,9 +430,7 @@ impl<'tcx> Validator<'_, 'tcx> {
                 self.validate_operand(op)?
             }
 
-            Rvalue::Discriminant(place) | Rvalue::Len(place) => {
-                self.validate_place(place.as_ref())?
-            }
+            Rvalue::Discriminant(place) => self.validate_place(place.as_ref())?,
 
             Rvalue::ThreadLocalRef(_) => return Err(Unpromotable),
 

compiler/rustc_mir_transform/src/validate.rs

@@ -1009,14 +1009,6 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                 }
             }
             Rvalue::Ref(..) => {}
-            Rvalue::Len(p) => {
-                let pty = p.ty(&self.body.local_decls, self.tcx).ty;
-                check_kinds!(
-                    pty,
-                    "Cannot compute length of non-array type {:?}",
-                    ty::Array(..) | ty::Slice(..)
-                );
-            }
             Rvalue::BinaryOp(op, vals) => {
                 use BinOp::*;
                 let a = vals.0.ty(&self.body.local_decls, self.tcx);

compiler/rustc_smir/src/rustc_smir/convert/mir.rs

@@ -181,7 +181,6 @@ impl<'tcx> Stable<'tcx> for mir::Rvalue<'tcx> {
             RawPtr(mutability, place) => {
                 stable_mir::mir::Rvalue::AddressOf(mutability.stable(tables), place.stable(tables))
             }
-            Len(place) => stable_mir::mir::Rvalue::Len(place.stable(tables)),
             Cast(cast_kind, op, ty) => stable_mir::mir::Rvalue::Cast(
                 cast_kind.stable(tables),
                 op.stable(tables),

compiler/rustc_span/src/symbol.rs

@@ -1282,7 +1282,6 @@ symbols! {
         mir_drop,
         mir_field,
         mir_goto,
-        mir_len,
         mir_make_place,
         mir_move,
         mir_offset,

library/core/src/intrinsics/mir.rs

@@ -233,7 +233,7 @@
 //!
 //!  - Operands implicitly convert to `Use` rvalues.
 //!  - `&`, `&mut`, `addr_of!`, and `addr_of_mut!` all work to create their associated rvalue.
-//!  - [`Discriminant`], [`Len`], and [`CopyForDeref`] have associated functions.
+//!  - [`Discriminant`] and [`CopyForDeref`] have associated functions.
 //!  - Unary and binary operations use their normal Rust syntax - `a * b`, `!c`, etc.
 //!  - The binary operation `Offset` can be created via [`Offset`].
 //!  - Checked binary operations are represented by wrapping the associated binop in [`Checked`].
@@ -401,7 +401,6 @@ define!("mir_storage_dead", fn StorageDead<T>(local: T));
 define!("mir_assume", fn Assume(operand: bool));
 define!("mir_deinit", fn Deinit<T>(place: T));
 define!("mir_checked", fn Checked<T>(binop: T) -> (T, bool));
-define!("mir_len", fn Len<T>(place: T) -> usize);
 define!(
     "mir_ptr_metadata",
     fn PtrMetadata<P: ?Sized>(place: *const P) -> <P as ::core::ptr::Pointee>::Metadata

src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs

@@ -109,7 +109,7 @@ fn check_rvalue<'tcx>(
 ) -> McfResult {
     match rvalue {
         Rvalue::ThreadLocalRef(_) => Err((span, "cannot access thread local storage in const fn".into())),
-        Rvalue::Len(place) | Rvalue::Discriminant(place) | Rvalue::Ref(_, _, place) | Rvalue::RawPtr(_, place) => {
+        Rvalue::Discriminant(place) | Rvalue::Ref(_, _, place) | Rvalue::RawPtr(_, place) => {
             check_place(tcx, *place, span, body, msrv)
         },
         Rvalue::CopyForDeref(place) => check_place(tcx, *place, span, body, msrv),

tests/mir-opt/building/custom/arrays.arrays.built.after.mir

@@ -22,14 +22,14 @@
 
       bb1: {
           StorageDead(_3);
-          _4 = Len((*_2));
+          _4 = PtrMetadata(copy _2);
           _5 = const 4_usize;
           _6 = Ge(move _4, move _5);
           switchInt(move _6) -> [0: bb2, otherwise: bb3];
       }
 
       bb2: {
-          _7 = Len((*_2));
+          _7 = PtrMetadata(copy _2);
           _8 = const 3_usize;
           _9 = Ge(move _7, move _8);
 -         switchInt(move _9) -> [0: bb7, otherwise: bb8];

tests/mir-opt/building/custom/arrays.rs

@@ -22,14 +22,14 @@
 
       bb1: {
           StorageDead(_3);
-          _4 = Len((*_2));
+          _4 = PtrMetadata(copy _2);
           _5 = const 4_usize;
           _6 = Ge(move _4, move _5);
           switchInt(move _6) -> [0: bb2, otherwise: bb3];
       }
 
       bb2: {
-          _7 = Len((*_2));
+          _7 = PtrMetadata(copy _2);
           _8 = const 3_usize;
           _9 = Ge(move _7, move _8);
 -         switchInt(move _9) -> [0: bb7, otherwise: bb8];

tests/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.panic-abort.diff

@@ -7,18 +7,16 @@
       let _2: &[T];
       let _3: &[T; 3];
       let _4: [T; 3];
-      let mut _5: usize;
-      let mut _6: bool;
-      let mut _10: !;
+      let mut _8: !;
       scope 1 {
           debug v => _2;
+          let _5: &T;
+          let _6: &T;
           let _7: &T;
-          let _8: &T;
-          let _9: &T;
           scope 2 {
-              debug v1 => _7;
-              debug v2 => _8;
-              debug v3 => _9;
+              debug v1 => _5;
+              debug v2 => _6;
+              debug v3 => _7;
           }
       }
 
@@ -27,25 +25,23 @@
           _4 = [copy _1, copy _1, copy _1];
           _3 = &_4;
           _2 = copy _3 as &[T] (PointerCoercion(Unsize, Implicit));
-          nop;
-          nop;
           goto -> bb2;
       }
 
       bb1: {
-          _10 = core::panicking::panic(const "internal error: entered unreachable code") -> unwind unreachable;
+          _8 = core::panicking::panic(const "internal error: entered unreachable code") -> unwind unreachable;
       }
 
       bb2: {
+          StorageLive(_5);
+          _5 = &(*_2)[0 of 3];
+          StorageLive(_6);
+          _6 = &(*_2)[1 of 3];
           StorageLive(_7);
-          _7 = &(*_2)[0 of 3];
-          StorageLive(_8);
-          _8 = &(*_2)[1 of 3];
-          StorageLive(_9);
-          _9 = &(*_2)[2 of 3];
-          StorageDead(_9);
-          StorageDead(_8);
+          _7 = &(*_2)[2 of 3];
           StorageDead(_7);
+          StorageDead(_6);
+          StorageDead(_5);
           StorageDead(_4);
           return;
       }

tests/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.panic-unwind.diff

@@ -7,18 +7,16 @@
       let _2: &[T];
       let _3: &[T; 3];
       let _4: [T; 3];
-      let mut _5: usize;
-      let mut _6: bool;
-      let mut _10: !;
+      let mut _8: !;
       scope 1 {
           debug v => _2;
+          let _5: &T;
+          let _6: &T;
           let _7: &T;
-          let _8: &T;
-          let _9: &T;
           scope 2 {
-              debug v1 => _7;
-              debug v2 => _8;
-              debug v3 => _9;
+              debug v1 => _5;
+              debug v2 => _6;
+              debug v3 => _7;
           }
       }
 
@@ -27,25 +25,23 @@
           _4 = [copy _1, copy _1, copy _1];
           _3 = &_4;
           _2 = copy _3 as &[T] (PointerCoercion(Unsize, Implicit));
-          nop;
-          nop;
           goto -> bb2;
       }
 
       bb1: {
-          _10 = core::panicking::panic(const "internal error: entered unreachable code") -> unwind continue;
+          _8 = core::panicking::panic(const "internal error: entered unreachable code") -> unwind continue;
       }
 
       bb2: {
+          StorageLive(_5);
+          _5 = &(*_2)[0 of 3];
+          StorageLive(_6);
+          _6 = &(*_2)[1 of 3];
           StorageLive(_7);
-          _7 = &(*_2)[0 of 3];
-          StorageLive(_8);
-          _8 = &(*_2)[1 of 3];
-          StorageLive(_9);
-          _9 = &(*_2)[2 of 3];
-          StorageDead(_9);
-          StorageDead(_8);
+          _7 = &(*_2)[2 of 3];
           StorageDead(_7);
+          StorageDead(_6);
+          StorageDead(_5);
           StorageDead(_4);
           return;
       }

tests/mir-opt/issue_76432.test.SimplifyComparisonIntegral.panic-abort.diff

@@ -92,7 +92,7 @@
           StorageDead(_7);
 -         StorageDead(_6);
 -         StorageLive(_10);
--         StorageLive(_11);
+          StorageLive(_11);
 -         StorageLive(_12);
           StorageLive(_13);
           _26 = const debuginfo::promoted[0];
@@ -105,9 +105,8 @@
       bb5: {
           StorageDead(_15);
           StorageDead(_13);
--         _11 = &(*_12);
--         _16 = Len((*_11));
-+         _16 = Len((*_12));
+          _11 = &(*_12);
+          _16 = PtrMetadata(copy _11);
           _17 = const 3_usize;
           _18 = Ge(move _16, move _17);
           switchInt(move _18) -> [0: bb7, otherwise: bb6];
@@ -137,7 +136,7 @@
 
       bb8: {
 -         StorageDead(_12);
--         StorageDead(_11);
+          StorageDead(_11);
 -         StorageDead(_10);
           StorageLive(_22);
           StorageLive(_23);