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;
24use crate::stable_mir;
25
26mod alloc;
27mod builder;
28pub mod context;
29mod convert;
30
31pub struct Tables<'tcx> {
32    pub(crate) tcx: TyCtxt<'tcx>,
33    pub(crate) def_ids: IndexMap<DefId, stable_mir::DefId>,
34    pub(crate) alloc_ids: IndexMap<AllocId, stable_mir::mir::alloc::AllocId>,
35    pub(crate) spans: IndexMap<rustc_span::Span, Span>,
36    pub(crate) types: IndexMap<Ty<'tcx>, stable_mir::ty::Ty>,
37    pub(crate) instances: IndexMap<ty::Instance<'tcx>, InstanceDef>,
38    pub(crate) ty_consts: IndexMap<ty::Const<'tcx>, TyConstId>,
39    pub(crate) mir_consts: IndexMap<mir::Const<'tcx>, MirConstId>,
40    pub(crate) layouts: IndexMap<rustc_abi::Layout<'tcx>, Layout>,
41}
42
43impl<'tcx> Tables<'tcx> {
44    pub(crate) fn intern_ty(&mut self, ty: Ty<'tcx>) -> stable_mir::ty::Ty {
45        self.types.create_or_fetch(ty)
46    }
47
48    pub(crate) fn intern_ty_const(&mut self, ct: ty::Const<'tcx>) -> TyConstId {
49        self.ty_consts.create_or_fetch(ct)
50    }
51
52    pub(crate) fn intern_mir_const(&mut self, constant: mir::Const<'tcx>) -> MirConstId {
53        self.mir_consts.create_or_fetch(constant)
54    }
55
56    /// Return whether the instance as a body available.
57    ///
58    /// Items and intrinsics may have a body available from its definition.
59    /// Shims body may be generated depending on their type.
60    pub(crate) fn instance_has_body(&self, instance: Instance<'tcx>) -> bool {
61        let def_id = instance.def_id();
62        self.item_has_body(def_id)
63            || !matches!(
64                instance.def,
65                ty::InstanceKind::Virtual(..)
66                    | ty::InstanceKind::Intrinsic(..)
67                    | ty::InstanceKind::Item(..)
68            )
69    }
70
71    /// Return whether the item has a body defined by the user.
72    ///
73    /// Note that intrinsics may have a placeholder body that shouldn't be used in practice.
74    /// In StableMIR, we handle this case as if the body is not available.
75    pub(crate) fn item_has_body(&self, def_id: DefId) -> bool {
76        let must_override = if let Some(intrinsic) = self.tcx.intrinsic(def_id) {
77            intrinsic.must_be_overridden
78        } else {
79            false
80        };
81        !must_override && self.tcx.is_mir_available(def_id)
82    }
83
84    fn to_fn_def(&mut self, def_id: DefId) -> Option<FnDef> {
85        if matches!(self.tcx.def_kind(def_id), DefKind::Fn | DefKind::AssocFn) {
86            Some(self.fn_def(def_id))
87        } else {
88            None
89        }
90    }
91
92    fn to_static(&mut self, def_id: DefId) -> Option<StaticDef> {
93        matches!(self.tcx.def_kind(def_id), DefKind::Static { .. }).then(|| self.static_def(def_id))
94    }
95}
96
97/// Iterate over the definitions of the given crate.
98pub(crate) fn filter_def_ids<F, T>(tcx: TyCtxt<'_>, krate: CrateNum, mut func: F) -> Vec<T>
99where
100    F: FnMut(DefId) -> Option<T>,
101{
102    if krate == LOCAL_CRATE {
103        tcx.iter_local_def_id().filter_map(|did| func(did.to_def_id())).collect()
104    } else {
105        let num_definitions = tcx.num_extern_def_ids(krate);
106        (0..num_definitions)
107            .filter_map(move |i| {
108                let def_id = DefId { krate, index: rustc_span::def_id::DefIndex::from_usize(i) };
109                func(def_id)
110            })
111            .collect()
112    }
113}
114
115/// Build a stable mir crate from a given crate number.
116pub(crate) fn smir_crate(tcx: TyCtxt<'_>, crate_num: CrateNum) -> stable_mir::Crate {
117    let crate_name = tcx.crate_name(crate_num).to_string();
118    let is_local = crate_num == LOCAL_CRATE;
119    debug!(?crate_name, ?crate_num, "smir_crate");
120    stable_mir::Crate { id: crate_num.into(), name: crate_name, is_local }
121}
122
123pub(crate) fn new_item_kind(kind: DefKind) -> ItemKind {
124    match kind {
125        DefKind::Mod
126        | DefKind::Struct
127        | DefKind::Union
128        | DefKind::Enum
129        | DefKind::Variant
130        | DefKind::Trait
131        | DefKind::TyAlias
132        | DefKind::ForeignTy
133        | DefKind::TraitAlias
134        | DefKind::AssocTy
135        | DefKind::TyParam
136        | DefKind::ConstParam
137        | DefKind::Macro(_)
138        | DefKind::ExternCrate
139        | DefKind::Use
140        | DefKind::ForeignMod
141        | DefKind::OpaqueTy
142        | DefKind::Field
143        | DefKind::LifetimeParam
144        | DefKind::Impl { .. }
145        | DefKind::GlobalAsm => {
146            unreachable!("Not a valid item kind: {kind:?}");
147        }
148        DefKind::Closure | DefKind::AssocFn | DefKind::Fn | DefKind::SyntheticCoroutineBody => {
149            ItemKind::Fn
150        }
151        DefKind::Const | DefKind::InlineConst | DefKind::AssocConst | DefKind::AnonConst => {
152            ItemKind::Const
153        }
154        DefKind::Static { .. } => ItemKind::Static,
155        DefKind::Ctor(_, rustc_hir::def::CtorKind::Const) => ItemKind::Ctor(CtorKind::Const),
156        DefKind::Ctor(_, rustc_hir::def::CtorKind::Fn) => ItemKind::Ctor(CtorKind::Fn),
157    }
158}
159
160/// Trait used to convert between an internal MIR type to a Stable MIR type.
161pub trait Stable<'cx> {
162    /// The stable representation of the type implementing Stable.
163    type T;
164    /// Converts an object to the equivalent Stable MIR representation.
165    fn stable(&self, tables: &mut Tables<'_>) -> Self::T;
166}
167
168impl<'tcx, T> Stable<'tcx> for &T
169where
170    T: Stable<'tcx>,
171{
172    type T = T::T;
173
174    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
175        (*self).stable(tables)
176    }
177}
178
179impl<'tcx, T> Stable<'tcx> for Option<T>
180where
181    T: Stable<'tcx>,
182{
183    type T = Option<T::T>;
184
185    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
186        self.as_ref().map(|value| value.stable(tables))
187    }
188}
189
190impl<'tcx, T, E> Stable<'tcx> for Result<T, E>
191where
192    T: Stable<'tcx>,
193    E: Stable<'tcx>,
194{
195    type T = Result<T::T, E::T>;
196
197    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
198        match self {
199            Ok(val) => Ok(val.stable(tables)),
200            Err(error) => Err(error.stable(tables)),
201        }
202    }
203}
204
205impl<'tcx, T> Stable<'tcx> for &[T]
206where
207    T: Stable<'tcx>,
208{
209    type T = Vec<T::T>;
210    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
211        self.iter().map(|e| e.stable(tables)).collect()
212    }
213}
214
215impl<'tcx, T, U> Stable<'tcx> for (T, U)
216where
217    T: Stable<'tcx>,
218    U: Stable<'tcx>,
219{
220    type T = (T::T, U::T);
221    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
222        (self.0.stable(tables), self.1.stable(tables))
223    }
224}
225
226impl<'tcx, T> Stable<'tcx> for RangeInclusive<T>
227where
228    T: Stable<'tcx>,
229{
230    type T = RangeInclusive<T::T>;
231    fn stable(&self, tables: &mut Tables<'_>) -> Self::T {
232        RangeInclusive::new(self.start().stable(tables), self.end().stable(tables))
233    }
234}