rustc_smir/rustc_smir/
mod.rs

1//! Module that implements what will become the rustc side of Stable MIR.
2
3//! This module is responsible for building Stable MIR components from internal components.
4//!
5//! This module is not intended to be invoked directly by users. It will eventually
6//! become the public API of rustc that will be invoked by the `stable_mir` crate.
7//!
8//! For now, we are developing everything inside `rustc`, thus, we keep this module private.
9
10use std::ops::RangeInclusive;
11
12use rustc_hir::def::DefKind;
13use rustc_middle::mir;
14use rustc_middle::mir::interpret::AllocId;
15use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
16use rustc_span::def_id::{CrateNum, DefId, LOCAL_CRATE};
17use stable_mir::abi::Layout;
18use stable_mir::mir::mono::{InstanceDef, StaticDef};
19use stable_mir::ty::{FnDef, MirConstId, Span, TyConstId};
20use stable_mir::{CtorKind, ItemKind};
21use tracing::debug;
22
23use crate::rustc_internal::IndexMap;
24
25mod alloc;
26mod builder;
27pub(crate) mod context;
28mod convert;
29
30pub struct Tables<'tcx> {
31    pub(crate) tcx: TyCtxt<'tcx>,
32    pub(crate) def_ids: IndexMap<DefId, stable_mir::DefId>,
33    pub(crate) alloc_ids: IndexMap<AllocId, stable_mir::mir::alloc::AllocId>,
34    pub(crate) spans: IndexMap<rustc_span::Span, Span>,
35    pub(crate) types: IndexMap<Ty<'tcx>, stable_mir::ty::Ty>,
36    pub(crate) instances: IndexMap<ty::Instance<'tcx>, InstanceDef>,
37    pub(crate) ty_consts: IndexMap<ty::Const<'tcx>, TyConstId>,
38    pub(crate) mir_consts: IndexMap<mir::Const<'tcx>, MirConstId>,
39    pub(crate) layouts: IndexMap<rustc_abi::Layout<'tcx>, Layout>,
40}
41
42impl<'tcx> Tables<'tcx> {
43    pub(crate) fn intern_ty(&mut self, ty: Ty<'tcx>) -> stable_mir::ty::Ty {
44        self.types.create_or_fetch(ty)
45    }
46
47    pub(crate) fn intern_ty_const(&mut self, ct: ty::Const<'tcx>) -> TyConstId {
48        self.ty_consts.create_or_fetch(ct)
49    }
50
51    pub(crate) fn intern_mir_const(&mut self, constant: mir::Const<'tcx>) -> MirConstId {
52        self.mir_consts.create_or_fetch(constant)
53    }
54
55    /// Return whether the instance as a body available.
56    ///
57    /// Items and intrinsics may have a body available from its definition.
58    /// Shims body may be generated depending on their type.
59    pub(crate) fn instance_has_body(&self, instance: Instance<'tcx>) -> bool {
60        let def_id = instance.def_id();
61        self.item_has_body(def_id)
62            || !matches!(
63                instance.def,
64                ty::InstanceKind::Virtual(..)
65                    | ty::InstanceKind::Intrinsic(..)
66                    | ty::InstanceKind::Item(..)
67            )
68    }
69
70    /// Return whether the item has a body defined by the user.
71    ///
72    /// Note that intrinsics may have a placeholder body that shouldn't be used in practice.
73    /// In StableMIR, we handle this case as if the body is not available.
74    pub(crate) fn item_has_body(&self, def_id: DefId) -> bool {
75        let must_override = if let Some(intrinsic) = self.tcx.intrinsic(def_id) {
76            intrinsic.must_be_overridden
77        } else {
78            false
79        };
80        !must_override && self.tcx.is_mir_available(def_id)
81    }
82
83    fn to_fn_def(&mut self, def_id: DefId) -> Option<FnDef> {
84        if matches!(self.tcx.def_kind(def_id), DefKind::Fn | DefKind::AssocFn) {
85            Some(self.fn_def(def_id))
86        } else {
87            None
88        }
89    }
90
91    fn to_static(&mut self, def_id: DefId) -> Option<StaticDef> {
92        matches!(self.tcx.def_kind(def_id), DefKind::Static { .. }).then(|| self.static_def(def_id))
93    }
94}
95
96/// Iterate over the definitions of the given crate.
97pub(crate) fn filter_def_ids<F, T>(tcx: TyCtxt<'_>, krate: CrateNum, mut func: F) -> Vec<T>
98where
99    F: FnMut(DefId) -> Option<T>,
100{
101    if krate == LOCAL_CRATE {
102        tcx.iter_local_def_id().filter_map(|did| func(did.to_def_id())).collect()
103    } else {
104        let num_definitions = tcx.num_extern_def_ids(krate);
105        (0..num_definitions)
106            .filter_map(move |i| {
107                let def_id = DefId { krate, index: rustc_span::def_id::DefIndex::from_usize(i) };
108                func(def_id)
109            })
110            .collect()
111    }
112}
113
114/// Build a stable mir crate from a given crate number.
115pub(crate) fn smir_crate(tcx: TyCtxt<'_>, crate_num: CrateNum) -> stable_mir::Crate {
116    let crate_name = tcx.crate_name(crate_num).to_string();
117    let is_local = crate_num == LOCAL_CRATE;
118    debug!(?crate_name, ?crate_num, "smir_crate");
119    stable_mir::Crate { id: crate_num.into(), name: crate_name, is_local }
120}
121
122pub(crate) fn new_item_kind(kind: DefKind) -> ItemKind {
123    match kind {
124        DefKind::Mod
125        | DefKind::Struct
126        | DefKind::Union
127        | DefKind::Enum
128        | DefKind::Variant
129        | DefKind::Trait
130        | DefKind::TyAlias
131        | DefKind::ForeignTy
132        | DefKind::TraitAlias
133        | DefKind::AssocTy
134        | DefKind::TyParam
135        | DefKind::ConstParam
136        | DefKind::Macro(_)
137        | DefKind::ExternCrate
138        | DefKind::Use
139        | DefKind::ForeignMod
140        | DefKind::OpaqueTy
141        | DefKind::Field
142        | DefKind::LifetimeParam
143        | DefKind::Impl { .. }
144        | DefKind::GlobalAsm => {
145            unreachable!("Not a valid item kind: {kind:?}");
146        }
147        DefKind::Closure | DefKind::AssocFn | DefKind::Fn | DefKind::SyntheticCoroutineBody => {
148            ItemKind::Fn
149        }
150        DefKind::Const | DefKind::InlineConst | DefKind::AssocConst | DefKind::AnonConst => {
151            ItemKind::Const
152        }
153        DefKind::Static { .. } => ItemKind::Static,
154        DefKind::Ctor(_, rustc_hir::def::CtorKind::Const) => ItemKind::Ctor(CtorKind::Const),
155        DefKind::Ctor(_, rustc_hir::def::CtorKind::Fn) => ItemKind::Ctor(CtorKind::Fn),
156    }
157}
158
159/// Trait used to convert between an internal MIR type to a Stable MIR type.
160pub trait Stable<'cx> {
161    /// The stable representation of the type implementing Stable.
162    type T;
163    /// Converts an object to the equivalent Stable MIR representation.
164    fn stable(&self, tables: &mut Tables<'_>) -> Self::T;
165}
166
167impl<'tcx, T> Stable<'tcx> for &T
168where
169    T: Stable<'tcx>,
170{
171    type T = T::T;
172
173    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
174        (*self).stable(tables)
175    }
176}
177
178impl<'tcx, T> Stable<'tcx> for Option<T>
179where
180    T: Stable<'tcx>,
181{
182    type T = Option<T::T>;
183
184    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
185        self.as_ref().map(|value| value.stable(tables))
186    }
187}
188
189impl<'tcx, T, E> Stable<'tcx> for Result<T, E>
190where
191    T: Stable<'tcx>,
192    E: Stable<'tcx>,
193{
194    type T = Result<T::T, E::T>;
195
196    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
197        match self {
198            Ok(val) => Ok(val.stable(tables)),
199            Err(error) => Err(error.stable(tables)),
200        }
201    }
202}
203
204impl<'tcx, T> Stable<'tcx> for &[T]
205where
206    T: Stable<'tcx>,
207{
208    type T = Vec<T::T>;
209    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
210        self.iter().map(|e| e.stable(tables)).collect()
211    }
212}
213
214impl<'tcx, T, U> Stable<'tcx> for (T, U)
215where
216    T: Stable<'tcx>,
217    U: Stable<'tcx>,
218{
219    type T = (T::T, U::T);
220    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
221        (self.0.stable(tables), self.1.stable(tables))
222    }
223}
224
225impl<'tcx, T> Stable<'tcx> for RangeInclusive<T>
226where
227    T: Stable<'tcx>,
228{
229    type T = RangeInclusive<T::T>;
230    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
231        RangeInclusive::new(self.start().stable(tables), self.end().stable(tables))
232    }
233}