1 files changed, 188 insertions, 18 deletions
diff --git a/compiler/stable_mir/src/mir/mono.rs b/compiler/stable_mir/src/mir/mono.rs
index 8f5333498..6c791ae85 100644
--- a/compiler/stable_mir/src/mir/mono.rs
+++ b/compiler/stable_mir/src/mir/mono.rs
@@ -1,16 +1,18 @@
+use crate::abi::FnAbi;
+use crate::crate_def::CrateDef;
 use crate::mir::Body;
-use crate::ty::{FnDef, GenericArgs, IndexedVal, Ty};
-use crate::{with, CrateItem, DefId, Error, Opaque};
-use std::fmt::Debug;
+use crate::ty::{Allocation, ClosureDef, ClosureKind, FnDef, GenericArgs, IndexedVal, Ty};
+use crate::{with, CrateItem, DefId, Error, ItemKind, Opaque, Symbol};
+use std::fmt::{Debug, Formatter};
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub enum MonoItem {
     Fn(Instance),
     Static(StaticDef),
     GlobalAsm(Opaque),
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Instance {
     /// The type of instance.
     pub kind: InstanceKind,
@@ -19,33 +21,75 @@ pub struct Instance {
     pub def: InstanceDef,
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub enum InstanceKind {
     /// A user defined item.
     Item,
     /// A compiler intrinsic function.
     Intrinsic,
     /// A virtual function definition stored in a VTable.
-    Virtual,
+    /// The `idx` field indicates the position in the VTable for this instance.
+    Virtual { idx: usize },
     /// A compiler generated shim.
     Shim,
 }
 
 impl Instance {
+    /// Get the arguments this instance was instantiated with.
+    pub fn args(&self) -> GenericArgs {
+        with(|cx| cx.instance_args(self.def))
+    }
+
     /// Get the body of an Instance. The body will be eagerly monomorphized.
-    pub fn body(&self) -> Body {
+    pub fn body(&self) -> Option<Body> {
         with(|context| context.instance_body(self.def))
     }
 
+    /// Check whether this instance has a body available.
+    ///
+    /// This call is much cheaper than `instance.body().is_some()`, since it doesn't try to build
+    /// the StableMIR body.
+    pub fn has_body(&self) -> bool {
+        with(|cx| cx.has_body(self.def.def_id()))
+    }
+
+    pub fn is_foreign_item(&self) -> bool {
+        with(|cx| cx.is_foreign_item(self.def.def_id()))
+    }
+
     /// Get the instance type with generic substitutions applied and lifetimes erased.
     pub fn ty(&self) -> Ty {
         with(|context| context.instance_ty(self.def))
     }
 
-    pub fn mangled_name(&self) -> String {
+    /// Retrieve information about this instance binary interface.
+    pub fn fn_abi(&self) -> Result<FnAbi, Error> {
+        with(|cx| cx.instance_abi(self.def))
+    }
+
+    /// Retrieve the instance's mangled name used for calling the given instance.
+    ///
+    /// This will also look up the correct name of instances from upstream crates.
+    pub fn mangled_name(&self) -> Symbol {
         with(|context| context.instance_mangled_name(self.def))
     }
 
+    /// Retrieve the instance name for diagnostic messages.
+    ///
+    /// This will return the specialized name, e.g., `std::vec::Vec<u8>::new`.
+    pub fn name(&self) -> Symbol {
+        with(|context| context.instance_name(self.def, false))
+    }
+
+    /// Return a trimmed name of the given instance including its args.
+    ///
+    /// If a symbol name can only be imported from one place for a type, and as
+    /// long as it was not glob-imported anywhere in the current crate, we trim its
+    /// path and print only the name.
+    pub fn trimmed_name(&self) -> Symbol {
+        with(|context| context.instance_name(self.def, true))
+    }
+
     /// Resolve an instance starting from a function definition and generic arguments.
     pub fn resolve(def: FnDef, args: &GenericArgs) -> Result<Instance, crate::Error> {
         with(|context| {
@@ -54,6 +98,64 @@ impl Instance {
             })
         })
     }
+
+    /// Resolve the drop in place for a given type.
+    pub fn resolve_drop_in_place(ty: Ty) -> Instance {
+        with(|cx| cx.resolve_drop_in_place(ty))
+    }
+
+    /// Resolve an instance for a given function pointer.
+    pub fn resolve_for_fn_ptr(def: FnDef, args: &GenericArgs) -> Result<Instance, crate::Error> {
+        with(|context| {
+            context.resolve_for_fn_ptr(def, args).ok_or_else(|| {
+                crate::Error::new(format!("Failed to resolve `{def:?}` with `{args:?}`"))
+            })
+        })
+    }
+
+    /// Resolve a closure with the expected kind.
+    pub fn resolve_closure(
+        def: ClosureDef,
+        args: &GenericArgs,
+        kind: ClosureKind,
+    ) -> Result<Instance, crate::Error> {
+        with(|context| {
+            context.resolve_closure(def, args, kind).ok_or_else(|| {
+                crate::Error::new(format!("Failed to resolve `{def:?}` with `{args:?}`"))
+            })
+        })
+    }
+
+    /// Check whether this instance is an empty shim.
+    ///
+    /// Allow users to check if this shim can be ignored when called directly.
+    ///
+    /// We have decided not to export different types of Shims to StableMIR users, however, this
+    /// is a query that can be very helpful for users when processing DropGlue.
+    ///
+    /// When generating code for a Drop terminator, users can ignore an empty drop glue.
+    /// These shims are only needed to generate a valid Drop call done via VTable.
+    pub fn is_empty_shim(&self) -> bool {
+        self.kind == InstanceKind::Shim && with(|cx| cx.is_empty_drop_shim(self.def))
+    }
+
+    /// Try to constant evaluate the instance into a constant with the given type.
+    ///
+    /// This can be used to retrieve a constant that represents an intrinsic return such as
+    /// `type_id`.
+    pub fn try_const_eval(&self, const_ty: Ty) -> Result<Allocation, Error> {
+        with(|cx| cx.eval_instance(self.def, const_ty))
+    }
+}
+
+impl Debug for Instance {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Instance")
+            .field("kind", &self.kind)
+            .field("def", &self.mangled_name())
+            .field("args", &self.args())
+            .finish()
+    }
 }
 
 /// Try to convert a crate item into an instance.
@@ -63,8 +165,9 @@ impl TryFrom<CrateItem> for Instance {
 
     fn try_from(item: CrateItem) -> Result<Self, Self::Error> {
         with(|context| {
-            if !context.requires_monomorphization(item.0) {
-                Ok(context.mono_instance(item))
+            let def_id = item.def_id();
+            if !context.requires_monomorphization(def_id) {
+                Ok(context.mono_instance(def_id))
             } else {
                 Err(Error::new("Item requires monomorphization".to_string()))
             }
@@ -78,19 +181,86 @@ impl TryFrom<Instance> for CrateItem {
     type Error = crate::Error;
 
     fn try_from(value: Instance) -> Result<Self, Self::Error> {
-        if value.kind == InstanceKind::Item {
-            Ok(CrateItem(with(|context| context.instance_def_id(value.def))))
+        with(|context| {
+            if value.kind == InstanceKind::Item && context.has_body(value.def.def_id()) {
+                Ok(CrateItem(context.instance_def_id(value.def)))
+            } else {
+                Err(Error::new(format!("Item kind `{:?}` cannot be converted", value.kind)))
+            }
+        })
+    }
+}
+
+impl From<Instance> for MonoItem {
+    fn from(value: Instance) -> Self {
+        MonoItem::Fn(value)
+    }
+}
+
+impl From<StaticDef> for MonoItem {
+    fn from(value: StaticDef) -> Self {
+        MonoItem::Static(value)
+    }
+}
+
+impl From<StaticDef> for CrateItem {
+    fn from(value: StaticDef) -> Self {
+        CrateItem(value.0)
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct InstanceDef(usize);
+
+impl CrateDef for InstanceDef {
+    fn def_id(&self) -> DefId {
+        with(|context| context.instance_def_id(*self))
+    }
+}
+
+crate_def! {
+    /// Holds information about a static variable definition.
+    pub StaticDef;
+}
+
+impl TryFrom<CrateItem> for StaticDef {
+    type Error = crate::Error;
+
+    fn try_from(value: CrateItem) -> Result<Self, Self::Error> {
+        if matches!(value.kind(), ItemKind::Static) {
+            Ok(StaticDef(value.0))
         } else {
-            Err(Error::new(format!("Item kind `{:?}` cannot be converted", value.kind)))
+            Err(Error::new(format!("Expected a static item, but found: {value:?}")))
         }
     }
 }
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub struct InstanceDef(usize);
+impl TryFrom<Instance> for StaticDef {
+    type Error = crate::Error;
+
+    fn try_from(value: Instance) -> Result<Self, Self::Error> {
+        StaticDef::try_from(CrateItem::try_from(value)?)
+    }
+}
 
-#[derive(Clone, Copy, PartialEq, Eq, Debug)]
-pub struct StaticDef(pub DefId);
+impl From<StaticDef> for Instance {
+    fn from(value: StaticDef) -> Self {
+        // A static definition should always be convertible to an instance.
+        with(|cx| cx.mono_instance(value.def_id()))
+    }
+}
+
+impl StaticDef {
+    /// Return the type of this static definition.
+    pub fn ty(&self) -> Ty {
+        with(|cx| cx.def_ty(self.0))
+    }
+
+    /// Evaluate a static's initializer, returning the allocation of the initializer's memory.
+    pub fn eval_initializer(&self) -> Result<Allocation, Error> {
+        with(|cx| cx.eval_static_initializer(*self))
+    }
+}
 
 impl IndexedVal for InstanceDef {
     fn to_val(index: usize) -> Self {