charon_lib/transform/simplify_output/
ops_to_function_calls.rs

1//! Desugar some unary/binary operations and the array repeats to function calls.
2//! For instance, we desugar ArrayToSlice from an unop to a function call.
3//! This allows a more uniform treatment later on.
4//! TODO: actually transform all the unops and binops to function calls?
5use crate::llbc_ast::*;
6use crate::transform::TransformCtx;
7
8use crate::transform::ctx::LlbcPass;
9
10fn transform_st(s: &mut Statement) {
11    match &s.kind {
12        // Transform the ArrayToSlice unop
13        StatementKind::Assign(
14            p,
15            Rvalue::UnaryOp(
16                UnOp::Cast(CastKind::Unsize(src_ty, tgt_ty, UnsizingMetadata::Length(_))),
17                op,
18            ),
19        ) => {
20            if let (
21                TyKind::Ref(_, deref!(TyKind::Adt(tref1)), kind1),
22                TyKind::Ref(_, deref!(TyKind::Adt(tref2)), kind2),
23            ) = (src_ty.kind(), tgt_ty.kind())
24                && matches!(tref1.id, TypeId::Builtin(BuiltinTy::Array))
25                && matches!(tref2.id, TypeId::Builtin(BuiltinTy::Slice))
26            {
27                // In MIR terminology, we go from &[T; l] to &[T] which means we
28                // effectively "unsize" the type, as `l` no longer appears in the
29                // destination type. At runtime, the converse happens: the length
30                // materializes into the fat pointer.
31                assert!(
32                    tref1.generics.types.elem_count() == 1
33                        && tref1.generics.const_generics.elem_count() == 1
34                );
35                assert!(tref1.generics.types[0] == tref2.generics.types[0]);
36                assert!(kind1 == kind2);
37                // We could avoid the clone operations below if we take the content of
38                // the statement. In practice, this shouldn't have much impact.
39                let id = match *kind1 {
40                    RefKind::Mut => BuiltinFunId::ArrayToSliceMut,
41                    RefKind::Shared => BuiltinFunId::ArrayToSliceShared,
42                };
43                let func = FnPtrKind::mk_builtin(id);
44                let generics = GenericArgs::new(
45                    [Region::Erased].into(),
46                    tref1.generics.types.clone(),
47                    tref1.generics.const_generics.clone(),
48                    [].into(),
49                );
50                s.kind = StatementKind::Call(Call {
51                    func: FnOperand::Regular(FnPtr::new(func, generics)),
52                    args: vec![op.clone()],
53                    dest: p.clone(),
54                });
55            }
56        }
57        // Transform the array aggregates to function calls
58        StatementKind::Assign(p, Rvalue::Repeat(op, ty, cg)) => {
59            // We could avoid the clone operations below if we take the content of
60            // the statement. In practice, this shouldn't have much impact.
61            let id = BuiltinFunId::ArrayRepeat;
62            let func = FnPtrKind::mk_builtin(id);
63            let generics = GenericArgs::new(
64                [Region::Erased].into(),
65                [ty.clone()].into(),
66                [cg.clone()].into(),
67                [].into(),
68            );
69            s.kind = StatementKind::Call(Call {
70                func: FnOperand::Regular(FnPtr::new(func, generics)),
71                args: vec![op.clone()],
72                dest: p.clone(),
73            });
74        }
75        // Transform the raw pointer aggregate to a function call
76        StatementKind::Assign(p, Rvalue::Aggregate(AggregateKind::RawPtr(ty, is_mut), ops)) => {
77            let id = BuiltinFunId::PtrFromParts(is_mut.clone());
78            let func = FnPtrKind::mk_builtin(id);
79            let generics = GenericArgs::new(
80                [Region::Erased].into(),
81                [ty.clone()].into(),
82                [].into(),
83                [].into(),
84            );
85
86            s.kind = StatementKind::Call(Call {
87                func: FnOperand::Regular(FnPtr::new(func, generics)),
88                args: ops.clone(),
89                dest: p.clone(),
90            });
91        }
92        _ => {}
93    }
94}
95
96pub struct Transform;
97impl LlbcPass for Transform {
98    fn transform_body(&self, ctx: &mut TransformCtx, b: &mut ExprBody) {
99        if ctx.options.no_ops_to_function_calls {
100            return;
101        }
102        b.body.visit_statements(&mut transform_st);
103    }
104}
charon_lib/transform/simplify_output/ops_to_function_calls.rs

charon_lib/transform/simplify_output/
ops_to_function_calls.rs
