Reapply "Auto merge of #133734 - scottmcm:lower-indexing-to-ptrmetadata, r=davidtwco,RalfJung"

This reverts commit 122a55bb442bd1995df9cf9b36e6f65ed3ef4a1d.

2 files changed, 0 insertions, 21 deletions

diff --git a/compiler/rustc_mir_transform/src/instsimplify.rs b/compiler/rustc_mir_transform/src/instsimplify.rs
index 4b9ebd40b85..3dc4edaaa5a 100644
--- a/compiler/rustc_mir_transform/src/instsimplify.rs
+++ b/compiler/rustc_mir_transform/src/instsimplify.rs
@@ -46,7 +46,6 @@ impl<'tcx> crate::MirPass<'tcx> for InstSimplify {
                         }
                         ctx.simplify_bool_cmp(rvalue);
                         ctx.simplify_ref_deref(rvalue);
-                        ctx.simplify_len(rvalue);
                         ctx.simplify_ptr_aggregate(rvalue);
                         ctx.simplify_cast(rvalue);
                         ctx.simplify_repeated_aggregate(rvalue);
@@ -166,18 +165,6 @@ impl<'tcx> InstSimplifyContext<'_, 'tcx> {
         }
     }
 
-    /// Transform `Len([_; N])` ==> `N`.
-    fn simplify_len(&self, rvalue: &mut Rvalue<'tcx>) {
-        if let Rvalue::Len(ref place) = *rvalue {
-            let place_ty = place.ty(self.local_decls, self.tcx).ty;
-            if let ty::Array(_, len) = *place_ty.kind() {
-                let const_ = Const::Ty(self.tcx.types.usize, len);
-                let constant = ConstOperand { span: DUMMY_SP, const_, user_ty: None };
-                *rvalue = Rvalue::Use(Operand::Constant(Box::new(constant)));
-            }
-        }
-    }
-
     /// Transform `Aggregate(RawPtr, [p, ()])` ==> `Cast(PtrToPtr, p)`.
     fn simplify_ptr_aggregate(&self, rvalue: &mut Rvalue<'tcx>) {
         if let Rvalue::Aggregate(box AggregateKind::RawPtr(pointee_ty, mutability), fields) = rvalue
diff --git a/compiler/rustc_mir_transform/src/validate.rs b/compiler/rustc_mir_transform/src/validate.rs
index 026923ad786..5881264cba5 100644
--- a/compiler/rustc_mir_transform/src/validate.rs
+++ b/compiler/rustc_mir_transform/src/validate.rs
@@ -1128,14 +1128,6 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                         );
                     }
                     UnOp::PtrMetadata => {
-                        if !matches!(self.body.phase, MirPhase::Runtime(_)) {
-                            // It would probably be fine to support this in earlier phases, but at
-                            // the time of writing it's only ever introduced from intrinsic
-                            // lowering or other runtime-phase optimization passes, so earlier
-                            // things can just `bug!` on it.
-                            self.fail(location, "PtrMetadata should be in runtime MIR only");
-                        }
-
                         check_kinds!(
                             a,
                             "Cannot PtrMetadata non-pointer non-reference type {:?}",