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::{Deserialize, Serialize};
14
15/// A raw statement: a statement without meta data.
16#[derive(
17    Debug, Clone, EnumIsA, EnumToGetters, EnumAsGetters, Serialize, Deserialize, Drive, DriveMut,
18)]
19pub enum RawStatement {
20    /// Assigns an `Rvalue` to a `Place`. e.g. `let y = x;` could become
21    /// `y := move x` which is represented as `Assign(y, Rvalue::Use(Operand::Move(x)))`.
22    Assign(Place, Rvalue),
23    /// Not used today because we take MIR built.
24    SetDiscriminant(Place, VariantId),
25    /// Equivalent to std::intrinsics::copy_nonoverlapping; this is not modelled as a function
26    /// call as it cannot diverge
27    CopyNonOverlapping(Box<CopyNonOverlapping>),
28    /// Indicates that this local should be allocated; if it is already allocated, this frees
29    /// the local and re-allocates it. The return value and arguments do not receive a
30    /// `StorageLive`. We ensure in the micro-pass `insert_storage_lives` that all other locals
31    /// have a `StorageLive` associated with them.
32    StorageLive(LocalId),
33    /// Indicates that this local should be deallocated; if it is already deallocated, this is
34    /// a no-op. A local may not have a `StorageDead` in the function's body, in which case it
35    /// is implicitly deallocated at the end of the function.
36    StorageDead(LocalId),
37    Deinit(Place),
38    /// Drop the value at the given place.
39    ///
40    /// For MIR built and promoted, this is a conditional drop: the value will only be dropped if
41    /// it has not already been moved out. For MIR elaborated and optimized, this is a real drop.
42    ///
43    /// This drop is then equivalent to a call to `std::ptr::drop_in_place(&raw mut place)`.
44    Drop(Place),
45    Assert(Assert),
46    Call(Call),
47    /// Panic also handles "unreachable". We keep the name of the panicking function that was
48    /// called.
49    Abort(AbortKind),
50    Return,
51    /// Break to outer loops.
52    /// The `usize` gives the index of the outer loop to break to:
53    /// * 0: break to first outer loop (the current loop)
54    /// * 1: break to second outer loop
55    /// * ...
56    #[drive(skip)]
57    Break(usize),
58    /// Continue to outer loops.
59    /// The `usize` gives the index of the outer loop to continue to:
60    /// * 0: continue to first outer loop (the current loop)
61    /// * 1: continue to second outer loop
62    /// * ...
63    #[drive(skip)]
64    Continue(usize),
65    /// No-op.
66    Nop,
67    Switch(Switch),
68    Loop(Block),
69    #[drive(skip)]
70    Error(String),
71}
72
73#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
74pub struct Statement {
75    pub span: Span,
76    pub content: RawStatement,
77    /// Comments that precede this statement.
78    // This is filled in a late pass after all the control-flow manipulation.
79    #[drive(skip)]
80    pub comments_before: Vec<String>,
81}
82
83#[derive(Debug, Clone, Serialize, Deserialize, Drive, DriveMut)]
84pub struct Block {
85    pub span: Span,
86    pub statements: Vec<Statement>,
87}
88
89#[derive(
90    Debug,
91    Clone,
92    EnumIsA,
93    EnumToGetters,
94    EnumAsGetters,
95    Serialize,
96    Deserialize,
97    Drive,
98    DriveMut,
99    VariantName,
100    VariantIndexArity,
101)]
102pub enum Switch {
103    /// Gives the `if` block and the `else` block. The `Operand` is the condition of the `if`, e.g. `if (y == 0)` could become
104    /// ```text
105    /// v@3 := copy y; // Represented as `Assign(v@3, Use(Copy(y))`
106    /// v@2 := move v@3 == 0; // Represented as `Assign(v@2, BinOp(BinOp::Eq, Move(y), Const(0)))`
107    /// if (move v@2) { // Represented as `If(Move(v@2), <then branch>, <else branch>)`
108    /// ```
109    If(Operand, Block, Block),
110    /// Gives the integer type, a map linking values to switch branches, and the
111    /// otherwise block. Note that matches over enumerations are performed by
112    /// switching over the discriminant, which is an integer.
113    /// Also, we use a `Vec` to make sure the order of the switch
114    /// branches is preserved.
115    ///
116    /// Rk.: we use a vector of values, because some of the branches may
117    /// be grouped together, like for the following code:
118    /// ```text
119    /// match e {
120    ///   E::V1 | E::V2 => ..., // Grouped
121    ///   E::V3 => ...
122    /// }
123    /// ```
124    SwitchInt(Operand, IntegerTy, Vec<(Vec<ScalarValue>, Block)>, Block),
125    /// A match over an ADT.
126    ///
127    /// The match statement is introduced in [crate::transform::remove_read_discriminant]
128    /// (whenever we find a discriminant read, we merge it with the subsequent
129    /// switch into a match).
130    Match(Place, Vec<(Vec<VariantId>, Block)>, Option<Block>),
131}
132
133pub type ExprBody = GExprBody<Block>;
charon_lib/ast/llbc_ast.rs

charon_lib/ast/
llbc_ast.rs
