rustc_smir/stable_mir/mir/
mono.rs

1use std::fmt::{Debug, Formatter};
2use std::io;
3
4use serde::Serialize;
5use stable_mir::abi::FnAbi;
6use stable_mir::crate_def::CrateDef;
7use stable_mir::mir::Body;
8use stable_mir::ty::{Allocation, ClosureDef, ClosureKind, FnDef, GenericArgs, IndexedVal, Ty};
9use stable_mir::{CrateItem, DefId, Error, ItemKind, Opaque, Symbol, with};
10
11use crate::stable_mir;
12
13#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
14pub enum MonoItem {
15    Fn(Instance),
16    Static(StaticDef),
17    GlobalAsm(Opaque),
18}
19
20#[derive(Copy, Clone, PartialEq, Eq, Hash, Serialize)]
21pub struct Instance {
22    /// The type of instance.
23    pub kind: InstanceKind,
24    /// An ID used to get the instance definition from the compiler.
25    /// Do not use this field directly.
26    pub def: InstanceDef,
27}
28
29#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Serialize)]
30pub enum InstanceKind {
31    /// A user defined item.
32    Item,
33    /// A compiler intrinsic function.
34    Intrinsic,
35    /// A virtual function definition stored in a VTable.
36    /// The `idx` field indicates the position in the VTable for this instance.
37    Virtual { idx: usize },
38    /// A compiler generated shim.
39    Shim,
40}
41
42impl Instance {
43    /// Get the arguments this instance was instantiated with.
44    pub fn args(&self) -> GenericArgs {
45        with(|cx| cx.instance_args(self.def))
46    }
47
48    /// Get the body of an Instance.
49    ///
50    /// The body will be eagerly monomorphized and all constants will already be evaluated.
51    ///
52    /// This method will return the intrinsic fallback body if one was defined.
53    pub fn body(&self) -> Option<Body> {
54        with(|context| context.instance_body(self.def))
55    }
56
57    /// Check whether this instance has a body available.
58    ///
59    /// For intrinsics with fallback body, this will return `true`. It is up to the user to decide
60    /// whether to specialize the intrinsic or to use its fallback body.
61    ///
62    /// For more information on fallback body, see <https://github.com/rust-lang/rust/issues/93145>.
63    ///
64    /// This call is much cheaper than `instance.body().is_some()`, since it doesn't try to build
65    /// the StableMIR body.
66    pub fn has_body(&self) -> bool {
67        with(|cx| cx.has_body(self.def.def_id()))
68    }
69
70    pub fn is_foreign_item(&self) -> bool {
71        with(|cx| cx.is_foreign_item(self.def.def_id()))
72    }
73
74    /// Get the instance type with generic instantiations applied and lifetimes erased.
75    pub fn ty(&self) -> Ty {
76        with(|context| context.instance_ty(self.def))
77    }
78
79    /// Retrieve information about this instance binary interface.
80    pub fn fn_abi(&self) -> Result<FnAbi, Error> {
81        with(|cx| cx.instance_abi(self.def))
82    }
83
84    /// Retrieve the instance's mangled name used for calling the given instance.
85    ///
86    /// This will also look up the correct name of instances from upstream crates.
87    pub fn mangled_name(&self) -> Symbol {
88        with(|context| context.instance_mangled_name(self.def))
89    }
90
91    /// Retrieve the instance name for diagnostic messages.
92    ///
93    /// This will return the specialized name, e.g., `std::vec::Vec<u8>::new`.
94    pub fn name(&self) -> Symbol {
95        with(|context| context.instance_name(self.def, false))
96    }
97
98    /// Return a trimmed name of the given instance including its args.
99    ///
100    /// If a symbol name can only be imported from one place for a type, and as
101    /// long as it was not glob-imported anywhere in the current crate, we trim its
102    /// path and print only the name.
103    pub fn trimmed_name(&self) -> Symbol {
104        with(|context| context.instance_name(self.def, true))
105    }
106
107    /// Retrieve the plain intrinsic name of an instance if it's an intrinsic.
108    ///
109    /// The plain name does not include type arguments (as `trimmed_name` does),
110    /// which is more convenient to match with intrinsic symbols.
111    pub fn intrinsic_name(&self) -> Option<Symbol> {
112        match self.kind {
113            InstanceKind::Intrinsic => {
114                Some(with(|context| context.intrinsic(self.def.def_id()).unwrap().fn_name()))
115            }
116            InstanceKind::Item | InstanceKind::Virtual { .. } | InstanceKind::Shim => None,
117        }
118    }
119
120    /// Resolve an instance starting from a function definition and generic arguments.
121    pub fn resolve(def: FnDef, args: &GenericArgs) -> Result<Instance, Error> {
122        with(|context| {
123            context
124                .resolve_instance(def, args)
125                .ok_or_else(|| Error::new(format!("Failed to resolve `{def:?}` with `{args:?}`")))
126        })
127    }
128
129    /// Resolve the drop in place for a given type.
130    pub fn resolve_drop_in_place(ty: Ty) -> Instance {
131        with(|cx| cx.resolve_drop_in_place(ty))
132    }
133
134    /// Resolve an instance for a given function pointer.
135    pub fn resolve_for_fn_ptr(def: FnDef, args: &GenericArgs) -> Result<Instance, Error> {
136        with(|context| {
137            context
138                .resolve_for_fn_ptr(def, args)
139                .ok_or_else(|| Error::new(format!("Failed to resolve `{def:?}` with `{args:?}`")))
140        })
141    }
142
143    /// Resolve a closure with the expected kind.
144    pub fn resolve_closure(
145        def: ClosureDef,
146        args: &GenericArgs,
147        kind: ClosureKind,
148    ) -> Result<Instance, Error> {
149        with(|context| {
150            context
151                .resolve_closure(def, args, kind)
152                .ok_or_else(|| Error::new(format!("Failed to resolve `{def:?}` with `{args:?}`")))
153        })
154    }
155
156    /// Check whether this instance is an empty shim.
157    ///
158    /// Allow users to check if this shim can be ignored when called directly.
159    ///
160    /// We have decided not to export different types of Shims to StableMIR users, however, this
161    /// is a query that can be very helpful for users when processing DropGlue.
162    ///
163    /// When generating code for a Drop terminator, users can ignore an empty drop glue.
164    /// These shims are only needed to generate a valid Drop call done via VTable.
165    pub fn is_empty_shim(&self) -> bool {
166        self.kind == InstanceKind::Shim && with(|cx| cx.is_empty_drop_shim(self.def))
167    }
168
169    /// Try to constant evaluate the instance into a constant with the given type.
170    ///
171    /// This can be used to retrieve a constant that represents an intrinsic return such as
172    /// `type_id`.
173    pub fn try_const_eval(&self, const_ty: Ty) -> Result<Allocation, Error> {
174        with(|cx| cx.eval_instance(self.def, const_ty))
175    }
176
177    /// Emit the body of this instance if it has one.
178    pub fn emit_mir<W: io::Write>(&self, w: &mut W) -> io::Result<()> {
179        if let Some(body) = self.body() { body.dump(w, &self.name()) } else { Ok(()) }
180    }
181}
182
183impl Debug for Instance {
184    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
185        f.debug_struct("Instance")
186            .field("kind", &self.kind)
187            .field("def", &self.mangled_name())
188            .field("args", &self.args())
189            .finish()
190    }
191}
192
193/// Try to convert a crate item into an instance.
194/// The item cannot be generic in order to be converted into an instance.
195impl TryFrom<CrateItem> for Instance {
196    type Error = stable_mir::Error;
197
198    fn try_from(item: CrateItem) -> Result<Self, Self::Error> {
199        with(|context| {
200            let def_id = item.def_id();
201            if !context.requires_monomorphization(def_id) {
202                Ok(context.mono_instance(def_id))
203            } else {
204                Err(Error::new("Item requires monomorphization".to_string()))
205            }
206        })
207    }
208}
209
210/// Try to convert an instance into a crate item.
211/// Only user defined instances can be converted.
212impl TryFrom<Instance> for CrateItem {
213    type Error = stable_mir::Error;
214
215    fn try_from(value: Instance) -> Result<Self, Self::Error> {
216        with(|context| {
217            if value.kind == InstanceKind::Item && context.has_body(value.def.def_id()) {
218                Ok(CrateItem(context.instance_def_id(value.def)))
219            } else {
220                Err(Error::new(format!("Item kind `{:?}` cannot be converted", value.kind)))
221            }
222        })
223    }
224}
225
226impl From<Instance> for MonoItem {
227    fn from(value: Instance) -> Self {
228        MonoItem::Fn(value)
229    }
230}
231
232impl From<StaticDef> for MonoItem {
233    fn from(value: StaticDef) -> Self {
234        MonoItem::Static(value)
235    }
236}
237
238impl From<StaticDef> for CrateItem {
239    fn from(value: StaticDef) -> Self {
240        CrateItem(value.0)
241    }
242}
243
244#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize)]
245pub struct InstanceDef(usize);
246
247impl CrateDef for InstanceDef {
248    fn def_id(&self) -> DefId {
249        with(|context| context.instance_def_id(*self))
250    }
251}
252
253crate_def! {
254    /// Holds information about a static variable definition.
255    #[derive(Serialize)]
256    pub StaticDef;
257}
258
259impl TryFrom<CrateItem> for StaticDef {
260    type Error = stable_mir::Error;
261
262    fn try_from(value: CrateItem) -> Result<Self, Self::Error> {
263        if matches!(value.kind(), ItemKind::Static) {
264            Ok(StaticDef(value.0))
265        } else {
266            Err(Error::new(format!("Expected a static item, but found: {value:?}")))
267        }
268    }
269}
270
271impl TryFrom<Instance> for StaticDef {
272    type Error = stable_mir::Error;
273
274    fn try_from(value: Instance) -> Result<Self, Self::Error> {
275        StaticDef::try_from(CrateItem::try_from(value)?)
276    }
277}
278
279impl From<StaticDef> for Instance {
280    fn from(value: StaticDef) -> Self {
281        // A static definition should always be convertible to an instance.
282        with(|cx| cx.mono_instance(value.def_id()))
283    }
284}
285
286impl StaticDef {
287    /// Return the type of this static definition.
288    pub fn ty(&self) -> Ty {
289        with(|cx| cx.def_ty(self.0))
290    }
291
292    /// Evaluate a static's initializer, returning the allocation of the initializer's memory.
293    pub fn eval_initializer(&self) -> Result<Allocation, Error> {
294        with(|cx| cx.eval_static_initializer(*self))
295    }
296}
297
298impl IndexedVal for InstanceDef {
299    fn to_val(index: usize) -> Self {
300        InstanceDef(index)
301    }
302    fn to_index(&self) -> usize {
303        self.0
304    }
305}
rustc_smir/stable_mir/mir/mono.rs

rustc_smir/stable_mir/mir/
mono.rs
