diff --git a/compiler/rustc_smir/src/rustc_internal/mod.rs b/compiler/rustc_smir/src/rustc_internal/mod.rs
index 87e0b211556b9..527d5220564cc 100644
--- a/compiler/rustc_smir/src/rustc_internal/mod.rs
+++ b/compiler/rustc_smir/src/rustc_internal/mod.rs
@@ -27,21 +27,33 @@ pub fn crate_item(did: DefId) -> stable_mir::CrateItem {
     with_tables(|t| t.crate_item(did))
 }
 
+pub fn adt_def(did: DefId) -> stable_mir::ty::AdtDef {
+    with_tables(|t| t.adt_def(did))
+}
+
 impl<'tcx> Tables<'tcx> {
     pub fn item_def_id(&self, item: &stable_mir::CrateItem) -> DefId {
         self.def_ids[item.0]
     }
 
     pub fn crate_item(&mut self, did: DefId) -> stable_mir::CrateItem {
+        stable_mir::CrateItem(self.create_def_id(did))
+    }
+
+    pub fn adt_def(&mut self, did: DefId) -> stable_mir::ty::AdtDef {
+        stable_mir::ty::AdtDef(self.create_def_id(did))
+    }
+
+    fn create_def_id(&mut self, did: DefId) -> stable_mir::DefId {
         // FIXME: this becomes inefficient when we have too many ids
         for (i, &d) in self.def_ids.iter().enumerate() {
             if d == did {
-                return stable_mir::CrateItem(i);
+                return i;
             }
         }
         let id = self.def_ids.len();
         self.def_ids.push(did);
-        stable_mir::CrateItem(id)
+        id
     }
 }
 
diff --git a/compiler/rustc_smir/src/rustc_smir/mod.rs b/compiler/rustc_smir/src/rustc_smir/mod.rs
index 7fb31df84d003..df682cd8f3ac3 100644
--- a/compiler/rustc_smir/src/rustc_smir/mod.rs
+++ b/compiler/rustc_smir/src/rustc_smir/mod.rs
@@ -8,7 +8,7 @@
 //! For now, we are developing everything inside `rustc`, thus, we keep this module private.
 
 use crate::rustc_internal::{self, opaque};
-use crate::stable_mir::ty::{FloatTy, IntTy, RigidTy, TyKind, UintTy};
+use crate::stable_mir::ty::{AdtSubsts, FloatTy, GenericArgKind, IntTy, RigidTy, TyKind, UintTy};
 use crate::stable_mir::{self, Context};
 use rustc_middle::mir;
 use rustc_middle::ty::{self, Ty, TyCtxt};
@@ -94,7 +94,25 @@ impl<'tcx> Tables<'tcx> {
                 ty::FloatTy::F32 => TyKind::RigidTy(RigidTy::Float(FloatTy::F32)),
                 ty::FloatTy::F64 => TyKind::RigidTy(RigidTy::Float(FloatTy::F64)),
             },
-            ty::Adt(_, _) => todo!(),
+            ty::Adt(adt_def, substs) => TyKind::RigidTy(RigidTy::Adt(
+                rustc_internal::adt_def(adt_def.did()),
+                AdtSubsts(
+                    substs
+                        .iter()
+                        .map(|arg| match arg.unpack() {
+                            ty::GenericArgKind::Lifetime(region) => {
+                                GenericArgKind::Lifetime(opaque(&region))
+                            }
+                            ty::GenericArgKind::Type(ty) => {
+                                GenericArgKind::Type(self.intern_ty(ty))
+                            }
+                            ty::GenericArgKind::Const(const_) => {
+                                GenericArgKind::Const(opaque(&const_))
+                            }
+                        })
+                        .collect(),
+                ),
+            )),
             ty::Foreign(_) => todo!(),
             ty::Str => todo!(),
             ty::Array(_, _) => todo!(),
@@ -149,13 +167,6 @@ pub(crate) trait Stable {
     fn stable(&self) -> Self::T;
 }
 
-impl Stable for DefId {
-    type T = stable_mir::CrateItem;
-    fn stable(&self) -> Self::T {
-        rustc_internal::crate_item(*self)
-    }
-}
-
 impl<'tcx> Stable for mir::Statement<'tcx> {
     type T = stable_mir::mir::Statement;
     fn stable(&self) -> Self::T {
@@ -190,7 +201,9 @@ impl<'tcx> Stable for mir::Rvalue<'tcx> {
             Ref(region, kind, place) => {
                 stable_mir::mir::Rvalue::Ref(opaque(region), kind.stable(), place.stable())
             }
-            ThreadLocalRef(def_id) => stable_mir::mir::Rvalue::ThreadLocalRef(def_id.stable()),
+            ThreadLocalRef(def_id) => {
+                stable_mir::mir::Rvalue::ThreadLocalRef(rustc_internal::crate_item(*def_id))
+            }
             AddressOf(mutability, place) => {
                 stable_mir::mir::Rvalue::AddressOf(mutability.stable(), place.stable())
             }
diff --git a/compiler/rustc_smir/src/stable_mir/ty.rs b/compiler/rustc_smir/src/stable_mir/ty.rs
index 3181af46e9cb3..389e3364117f0 100644
--- a/compiler/rustc_smir/src/stable_mir/ty.rs
+++ b/compiler/rustc_smir/src/stable_mir/ty.rs
@@ -1,4 +1,5 @@
-use super::with;
+use super::{with, DefId};
+use crate::rustc_internal::Opaque;
 
 #[derive(Copy, Clone, Debug)]
 pub struct Ty(pub usize);
@@ -9,6 +10,9 @@ impl Ty {
     }
 }
 
+type Const = Opaque;
+type Region = Opaque;
+
 #[derive(Clone, Debug)]
 pub enum TyKind {
     RigidTy(RigidTy),
@@ -21,6 +25,7 @@ pub enum RigidTy {
     Int(IntTy),
     Uint(UintTy),
     Float(FloatTy),
+    Adt(AdtDef, AdtSubsts),
     Tuple(Vec<Ty>),
 }
 
@@ -49,3 +54,18 @@ pub enum FloatTy {
     F32,
     F64,
 }
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct AdtDef(pub(crate) DefId);
+
+#[derive(Clone, Debug)]
+pub struct AdtSubsts(pub Vec<GenericArgKind>);
+
+#[derive(Clone, Debug)]
+pub enum GenericArgKind {
+    // FIXME add proper region
+    Lifetime(Region),
+    Type(Ty),
+    // FIXME add proper const
+    Const(Const),
+}