charon_lib/ast/gast.rs
1//! Definitions common to [crate::ullbc_ast] and [crate::llbc_ast]
2use crate::ast::*;
3use crate::ids::Vector;
4use crate::llbc_ast;
5use crate::ullbc_ast;
6use derive_generic_visitor::{Drive, DriveMut};
7use indexmap::IndexMap;
8use macros::{EnumIsA, EnumToGetters};
9use serde::{Deserialize, Serialize};
10
11/// A variable
12#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
13pub struct Local {
14 /// Unique index identifying the variable
15 pub index: LocalId,
16 /// Variable name - may be `None` if the variable was introduced by Rust
17 /// through desugaring.
18 #[drive(skip)]
19 pub name: Option<String>,
20 /// The variable type
21 #[charon::rename("var_ty")]
22 pub ty: Ty,
23}
24#[deprecated(note = "use `Local` intead")]
25pub type Var = Local;
26#[deprecated(note = "use `LocalId` intead")]
27pub type VarId = LocalId;
28
29/// Marker to indicate that a declaration is opaque (i.e. we don't inspect its body).
30#[derive(Debug, Copy, Clone, Serialize, Deserialize, Drive, DriveMut)]
31pub struct Opaque;
32
33/// The local variables of a body.
34#[derive(Debug, Default, Clone, Serialize, Deserialize, Drive, DriveMut)]
35pub struct Locals {
36 /// The number of local variables used for the input arguments.
37 #[drive(skip)]
38 pub arg_count: usize,
39 /// The local variables.
40 /// We always have, in the following order:
41 /// - the local used for the return value (index 0)
42 /// - the `arg_count` input arguments
43 /// - the remaining locals, used for the intermediate computations
44 pub locals: Vector<LocalId, Local>,
45}
46
47/// An expression body.
48/// TODO: arg_count should be stored in GFunDecl below. But then,
49/// the print is obfuscated and Aeneas may need some refactoring.
50#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
51#[charon::rename("GexprBody")]
52pub struct GExprBody<T> {
53 pub span: Span,
54 /// The local variables.
55 pub locals: Locals,
56 /// For each line inside the body, we record any whole-line `//` comments found before it. They
57 /// are added to statements in the late `recover_body_comments` pass.
58 #[charon::opaque]
59 #[drive(skip)]
60 pub comments: Vec<(usize, Vec<String>)>,
61 pub body: T,
62}
63
64/// The body of a function or a constant.
65#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut, EnumIsA, EnumToGetters)]
66pub enum Body {
67 /// Body represented as a CFG. This is what ullbc is made of, and what we get after translating MIR.
68 Unstructured(ullbc_ast::ExprBody),
69 /// Body represented with structured control flow. This is what llbc is made of. We restructure
70 /// the control flow in `ullbc_to_llbc`.
71 Structured(llbc_ast::ExprBody),
72}
73
74/// Item kind: whether this function/const is part of a trait declaration, trait implementation, or
75/// neither.
76///
77/// Example:
78/// ```text
79/// trait Foo {
80/// fn bar(x : u32) -> u32; // trait item decl without default
81///
82/// fn baz(x : bool) -> bool { x } // trait item decl with default
83/// }
84///
85/// impl Foo for ... {
86/// fn bar(x : u32) -> u32 { x } // trait item implementation
87/// }
88///
89/// fn test(...) { ... } // regular
90///
91/// impl Type {
92/// fn test(...) { ... } // regular
93/// }
94/// ```
95#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut, PartialEq, Eq)]
96#[charon::variants_suffix("Item")]
97pub enum ItemKind {
98 /// A function/const at the top level or in an inherent impl block.
99 Regular,
100 /// Function/const that is part of a trait declaration. It has a body if and only if the trait
101 /// provided a default implementation.
102 TraitDecl {
103 /// The trait declaration this item belongs to.
104 trait_ref: TraitDeclRef,
105 /// The name of the item.
106 // TODO: also include method generics so we can recover a full `FnPtr::TraitMethod`
107 #[drive(skip)]
108 item_name: TraitItemName,
109 /// Whether the trait declaration provides a default implementation.
110 #[drive(skip)]
111 has_default: bool,
112 },
113 /// Function/const that is part of a trait implementation.
114 TraitImpl {
115 /// The trait implementation the method belongs to.
116 impl_ref: TraitImplRef,
117 /// The trait declaration that the impl block implements.
118 trait_ref: TraitDeclRef,
119 /// The name of the item
120 // TODO: also include method generics so we can recover a full `FnPtr::TraitMethod`
121 #[drive(skip)]
122 item_name: TraitItemName,
123 /// True if the trait decl had a default implementation for this function/const and this
124 /// item is a copy of the default item.
125 #[drive(skip)]
126 reuses_default: bool,
127 },
128}
129
130/// A function definition
131#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
132pub struct FunDecl {
133 #[drive(skip)]
134 pub def_id: FunDeclId,
135 /// The meta data associated with the declaration.
136 pub item_meta: ItemMeta,
137 /// The signature contains the inputs/output types *with* non-erased regions.
138 /// It also contains the list of region and type parameters.
139 pub signature: FunSig,
140 /// The function kind: "regular" function, trait method declaration, etc.
141 pub kind: ItemKind,
142 /// Whether this function is in fact the body of a constant/static that we turned into an
143 /// initializer function.
144 pub is_global_initializer: Option<GlobalDeclId>,
145 /// The function body, unless the function is opaque.
146 /// Opaque functions are: external functions, or local functions tagged
147 /// as opaque.
148 pub body: Result<Body, Opaque>,
149}
150
151/// Reference to a function declaration.
152#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Hash, Drive, DriveMut)]
153pub struct FunDeclRef {
154 #[charon::rename("fun_id")]
155 pub id: FunDeclId,
156 /// Generic arguments passed to the function.
157 #[charon::rename("fun_generics")]
158 pub generics: GenericArgs,
159}
160
161#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
162pub enum GlobalKind {
163 /// A static.
164 Static,
165 /// A const with a name (either top-level or an associated const in a trait).
166 NamedConst,
167 /// A const without a name:
168 /// - An inline const expression (`const { 1 + 1 }`);
169 /// - A const expression in a type (`[u8; sizeof::<T>()]`);
170 /// - A promoted constant, automatically lifted from a body (`&0`).
171 AnonConst,
172}
173
174/// A global variable definition (constant or static).
175#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
176pub struct GlobalDecl {
177 #[drive(skip)]
178 pub def_id: GlobalDeclId,
179 /// The meta data associated with the declaration.
180 pub item_meta: ItemMeta,
181 pub generics: GenericParams,
182 pub ty: Ty,
183 /// The context of the global: distinguishes top-level items from trait-associated items.
184 pub kind: ItemKind,
185 /// The kind of global (static or const).
186 #[drive(skip)]
187 pub global_kind: GlobalKind,
188 /// The initializer function used to compute the initial value for this constant/static. It
189 /// uses the same generic parameters as the global.
190 #[charon::rename("body")]
191 pub init: FunDeclId,
192}
193
194/// Reference to a global declaration.
195#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Hash, Drive, DriveMut)]
196pub struct GlobalDeclRef {
197 #[charon::rename("global_id")]
198 pub id: GlobalDeclId,
199 #[charon::rename("global_generics")]
200 pub generics: GenericArgs,
201}
202
203#[derive(
204 Debug, Clone, Serialize, Deserialize, Drive, DriveMut, PartialEq, Eq, Hash, PartialOrd, Ord,
205)]
206#[drive(skip)]
207pub struct TraitItemName(pub String);
208
209/// A trait **declaration**.
210///
211/// For instance:
212/// ```text
213/// trait Foo {
214/// type Bar;
215///
216/// fn baz(...); // required method (see below)
217///
218/// fn test() -> bool { true } // provided method (see below)
219/// }
220/// ```
221///
222/// In case of a trait declaration, we don't include the provided methods (the methods
223/// with a default implementation): they will be translated on a per-need basis. This is
224/// important for two reasons:
225/// - this makes the trait definitions a lot smaller (the Iterator trait
226/// has *one* declared function and more than 70 provided functions)
227/// - this is important for the external traits, whose provided methods
228/// often use features we don't support yet
229///
230/// Remark:
231/// In Aeneas, we still translate the provided methods on an individual basis,
232/// and in such a way thay they take as input a trait instance. This means that
233/// we can use default methods *but*:
234/// - implementations of required methods shoudln't call default methods
235/// - trait implementations shouldn't redefine required methods
236/// The use case we have in mind is [std::iter::Iterator]: it declares one required
237/// method (`next`) that should be implemented for every iterator, and defines many
238/// helpers like `all`, `map`, etc. that shouldn't be re-implemented.
239/// Of course, this forbids other useful use cases such as visitors implemented
240/// by means of traits.
241#[allow(clippy::type_complexity)]
242#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
243pub struct TraitDecl {
244 #[drive(skip)]
245 pub def_id: TraitDeclId,
246 pub item_meta: ItemMeta,
247 pub generics: GenericParams,
248 /// The "parent" clauses: the supertraits.
249 ///
250 /// Supertraits are actually regular where clauses, but we decided to have
251 /// a custom treatment.
252 /// ```text
253 /// trait Foo : Bar {
254 /// ^^^
255 /// supertrait, that we treat as a parent predicate
256 /// }
257 /// ```
258 /// TODO: actually, as of today, we consider that all trait clauses of
259 /// trait declarations are parent clauses.
260 pub parent_clauses: Vector<TraitClauseId, TraitClause>,
261 /// The associated constants declared in the trait, along with their type.
262 pub consts: Vec<(TraitItemName, Ty)>,
263 /// Records associated constants that have a default value.
264 #[charon::opaque]
265 pub const_defaults: IndexMap<TraitItemName, GlobalDeclRef>,
266 /// The associated types declared in the trait.
267 pub types: Vec<TraitItemName>,
268 /// Records associated types that have a default value.
269 #[charon::opaque]
270 pub type_defaults: IndexMap<TraitItemName, Ty>,
271 /// List of trait clauses that apply to each associated type. This is used during translation,
272 /// but the `lift_associated_item_clauses` pass moves them to be parent clauses later. Hence
273 /// this is empty after that pass.
274 /// TODO: Do this as we translate to avoid the need to store this vector.
275 #[charon::opaque]
276 pub type_clauses: Vec<(TraitItemName, Vector<TraitClauseId, TraitClause>)>,
277 /// The methods declared by the trait. The signature of the methods can be found in each
278 /// corresponding `FunDecl`. These `FunDecl` may have a body if the trait provided a default
279 /// implementation for that method; otherwise it has an `Opaque` body.
280 ///
281 /// The binder contains the type parameters specific to the method. The `FunDeclRef` then
282 /// provides a full list of arguments to the pointed-to function.
283 pub methods: Vec<(TraitItemName, Binder<FunDeclRef>)>,
284}
285
286/// A trait **implementation**.
287///
288/// For instance:
289/// ```text
290/// impl Foo for List {
291/// type Bar = ...
292///
293/// fn baz(...) { ... }
294/// }
295/// ```
296#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
297pub struct TraitImpl {
298 #[drive(skip)]
299 pub def_id: TraitImplId,
300 pub item_meta: ItemMeta,
301 /// The information about the implemented trait.
302 /// Note that this contains the instantiation of the "parent"
303 /// clauses.
304 pub impl_trait: TraitDeclRef,
305 pub generics: GenericParams,
306 /// The trait references for the parent clauses (see [TraitDecl]).
307 pub parent_trait_refs: Vector<TraitClauseId, TraitRef>,
308 /// The associated constants declared in the trait.
309 pub consts: Vec<(TraitItemName, GlobalDeclRef)>,
310 /// The associated types declared in the trait.
311 pub types: Vec<(TraitItemName, Ty)>,
312 /// The `Vec` corresponds to the same `Vector` in `TraitDecl`. In the same way, this is
313 /// empty after the `lift_associated_item_clauses` pass.
314 #[charon::opaque]
315 pub type_clauses: Vec<(TraitItemName, Vector<TraitClauseId, TraitRef>)>,
316 /// The implemented methods
317 pub methods: Vec<(TraitItemName, Binder<FunDeclRef>)>,
318}
319
320/// A function operand is used in function calls.
321/// It either designates a top-level function, or a place in case
322/// we are using function pointers stored in local variables.
323#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
324#[charon::variants_prefix("FnOp")]
325pub enum FnOperand {
326 /// Regular case: call to a top-level function, trait method, etc.
327 Regular(FnPtr),
328 /// Use of a function pointer stored in a local variable
329 Move(Place),
330}
331
332#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
333pub struct Call {
334 pub func: FnOperand,
335 pub args: Vec<Operand>,
336 pub dest: Place,
337}
338
339/// (U)LLBC is a language with side-effects: a statement may abort in a way that isn't tracked by
340/// control-flow. The two kinds of abort are:
341/// - Panic (may unwind or not depending on compilation setting);
342/// - Undefined behavior:
343#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
344pub enum AbortKind {
345 /// A built-in panicking function.
346 Panic(Option<Name>),
347 /// Undefined behavior in the rust abstract machine.
348 UndefinedBehavior,
349}
350
351/// Check the value of an operand and abort if the value is not expected. This is introduced to
352/// avoid a lot of small branches.
353///
354/// We translate MIR asserts (introduced for out-of-bounds accesses or divisions by zero for
355/// instance) to this. We then eliminate them in [crate::remove_dynamic_checks], because they're
356/// implicit in the semantics of our array accesses etc. Finally we introduce new asserts in
357/// [crate::reconstruct_asserts].
358#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
359#[charon::rename("Assertion")]
360pub struct Assert {
361 pub cond: Operand,
362 /// The value that the operand should evaluate to for the assert to succeed.
363 #[drive(skip)]
364 pub expected: bool,
365 /// What kind of abort happens on assert failure.
366 pub on_failure: AbortKind,
367}