charon_lib/ast/
llbc_ast.rs

1//! LLBC
2//!
3//! MIR code where we have rebuilt the control-flow (`if ... then ... else ...`,
4//! `while ...`, ...).
5//!
6//! Also note that we completely break the definitions Statement and Terminator
7//! from MIR to use Statement only.
8
9pub use super::llbc_ast_utils::*;
10pub use crate::ast::*;
11use derive_generic_visitor::{Drive, DriveMut};
12use macros::{EnumAsGetters, EnumIsA, EnumToGetters, VariantIndexArity, VariantName};
13use serde_state::{DeserializeState, SerializeState};
14
15generate_index_type!(StatementId);
16
17/// A raw statement: a statement without meta data.
18#[derive(
19    Debug,
20    PartialEq,
21    Eq,
22    Clone,
23    EnumIsA,
24    EnumToGetters,
25    EnumAsGetters,
26    SerializeState,
27    DeserializeState,
28    Drive,
29    DriveMut,
30)]
31pub enum StatementKind {
32    /// Assigns an `Rvalue` to a `Place`. e.g. `let y = x;` could become
33    /// `y := move x` which is represented as `Assign(y, Rvalue::Use(Operand::Move(x)))`.
34    Assign(Place, Rvalue),
35    /// Not used today because we take MIR built.
36    SetDiscriminant(Place, VariantId),
37    /// Equivalent to std::intrinsics::copy_nonoverlapping; this is not modelled as a function
38    /// call as it cannot diverge
39    CopyNonOverlapping(Box<CopyNonOverlapping>),
40    /// Indicates that this local should be allocated; if it is already allocated, this frees
41    /// the local and re-allocates it. The return value and arguments do not receive a
42    /// `StorageLive`. We ensure in the micro-pass `insert_storage_lives` that all other locals
43    /// have a `StorageLive` associated with them.
44    StorageLive(LocalId),
45    /// Indicates that this local should be deallocated; if it is already deallocated, this is
46    /// a no-op. A local may not have a `StorageDead` in the function's body, in which case it
47    /// is implicitly deallocated at the end of the function.
48    StorageDead(LocalId),
49    /// A place is mentioned, but not accessed. The place itself must still be valid though, so
50    /// this statement is not a no-op: it can trigger UB if the place's projections are not valid
51    /// (e.g. because they go out of bounds).
52    PlaceMention(Place),
53    /// Drop the value at the given place.
54    ///
55    /// Depending on `DropKind`, this may be a real call to `drop_in_place`, or a conditional call
56    /// that should only happen if the place has not been moved out of. See the docs of `DropKind`
57    /// for more details; to get precise drops use `--precise-drops`.
58    Drop(Place, TraitRef, #[drive(skip)] DropKind),
59    Assert {
60        assert: Assert,
61        on_failure: AbortKind,
62    },
63    Call(Call),
64    /// Panic also handles "unreachable". We keep the name of the panicking function that was
65    /// called.
66    Abort(AbortKind),
67    Return,
68    /// Break to outer loops.
69    /// The `usize` gives the index of the outer loop to break to:
70    /// * 0: break to first outer loop (the current loop)
71    /// * 1: break to second outer loop
72    /// * ...
73    #[drive(skip)]
74    Break(usize),
75    /// Continue to outer loops.
76    /// The `usize` gives the index of the outer loop to continue to:
77    /// * 0: continue to first outer loop (the current loop)
78    /// * 1: continue to second outer loop
79    /// * ...
80    #[drive(skip)]
81    Continue(usize),
82    /// No-op.
83    Nop,
84    Switch(Switch),
85    Loop(Block),
86    #[drive(skip)]
87    Error(String),
88}
89
90#[derive(Debug, Eq, Clone, SerializeState, DeserializeState, Drive, DriveMut)]
91pub struct Statement {
92    pub span: Span,
93    /// Integer uniquely identifying this statement among the statmeents in the current body. To
94    /// simplify things we generate globally-fresh ids when creating a new `Statement`.
95    #[charon::rename("statement_id")]
96    pub id: StatementId,
97    pub kind: StatementKind,
98    /// Comments that precede this statement.
99    // This is filled in a late pass after all the control-flow manipulation.
100    #[drive(skip)]
101    pub comments_before: Vec<String>,
102}
103
104/// Ignores statement ids.
105impl PartialEq for Statement {
106    fn eq(&self, other: &Self) -> bool {
107        self.span == other.span
108            && self.kind == other.kind
109            && self.comments_before == other.comments_before
110    }
111}
112
113#[derive(Debug, PartialEq, Eq, Clone, SerializeState, DeserializeState, Drive, DriveMut)]
114#[serde_state(state_implements = HashConsSerializerState)] // Avoid corecursive impls due to perfect derive
115pub struct Block {
116    pub span: Span,
117    pub statements: Vec<Statement>,
118}
119
120#[derive(
121    Debug,
122    PartialEq,
123    Eq,
124    Clone,
125    EnumIsA,
126    EnumToGetters,
127    EnumAsGetters,
128    SerializeState,
129    DeserializeState,
130    Drive,
131    DriveMut,
132    VariantName,
133    VariantIndexArity,
134)]
135pub enum Switch {
136    /// Gives the `if` block and the `else` block. The `Operand` is the condition of the `if`, e.g. `if (y == 0)` could become
137    /// ```text
138    /// v@3 := copy y; // Represented as `Assign(v@3, Use(Copy(y))`
139    /// v@2 := move v@3 == 0; // Represented as `Assign(v@2, BinOp(BinOp::Eq, Move(y), Const(0)))`
140    /// if (move v@2) { // Represented as `If(Move(v@2), <then branch>, <else branch>)`
141    /// ```
142    If(Operand, Block, Block),
143    /// Gives the integer type, a map linking values to switch branches, and the
144    /// otherwise block. Note that matches over enumerations are performed by
145    /// switching over the discriminant, which is an integer.
146    /// Also, we use a `Vec` to make sure the order of the switch
147    /// branches is preserved.
148    ///
149    /// Rk.: we use a vector of values, because some of the branches may
150    /// be grouped together, like for the following code:
151    /// ```text
152    /// match e {
153    ///   E::V1 | E::V2 => ..., // Grouped
154    ///   E::V3 => ...
155    /// }
156    /// ```
157    SwitchInt(Operand, LiteralTy, Vec<(Vec<Literal>, Block)>, Block),
158    /// A match over an ADT.
159    ///
160    /// The match statement is introduced in [crate::transform::resugar::reconstruct_matches]
161    /// (whenever we find a discriminant read, we merge it with the subsequent
162    /// switch into a match).
163    Match(Place, Vec<(Vec<VariantId>, Block)>, Option<Block>),
164}
165
166pub type ExprBody = GExprBody<Block>;
charon_lib/ast/llbc_ast.rs

charon_lib/ast/
llbc_ast.rs
