charon_lib/transform/resugar/
inline_local_panic_functions.rs

1//! `panic!()` expands to:
2//! ```ignore
3//! fn panic_cold_explicit() -> ! {
4//!     core::panicking::panic_explicit()
5//! }
6//! panic_cold_explicit()
7//! ```
8//! Which defines a new function each time. This pass recognizes these functions and replaces calls
9//! to them by a `Panic` terminator.
10use std::collections::HashSet;
11
12use crate::transform::{TransformCtx, ctx::UllbcPass};
13use crate::{builtins, names::Name, ullbc_ast::*};
14
15pub struct Transform;
16impl UllbcPass for Transform {
17    fn transform_ctx(&self, ctx: &mut TransformCtx) {
18        // Collect the functions that were generated by the `panic!` macro.
19        let mut panic_fns = HashSet::new();
20        ctx.for_each_fun_decl(|_ctx, decl| {
21            if let Some(body) = decl.body.as_unstructured() {
22                // If the whole body is only a call to this specific panic function.
23                if body.body.elem_count() == 1
24                    && let Some(block) = body.body.iter().next()
25                    && block.statements.is_empty()
26                    && let TerminatorKind::Abort(AbortKind::Panic(Some(name))) =
27                        &block.terminator.kind
28                {
29                    if name.equals_ref_name(builtins::EXPLICIT_PANIC_NAME) {
30                        // FIXME: also check that the name of the function is
31                        // `panic_cold_explicit`?
32                        panic_fns.insert(decl.def_id);
33                    }
34                }
35            }
36        });
37
38        let panic_name = Name::from_path(builtins::EXPLICIT_PANIC_NAME);
39        let panic_terminator = TerminatorKind::Abort(AbortKind::Panic(Some(panic_name)));
40
41        // Replace each call to one such function with a `Panic`.
42        ctx.for_each_fun_decl(|_ctx, decl| {
43            if let Some(body) = decl.body.as_unstructured_mut() {
44                for block_id in body.body.all_indices() {
45                    let Some(block) = body.body.get_mut(block_id) else {
46                        continue;
47                    };
48                    if let TerminatorKind::Call {
49                        call:
50                            Call {
51                                func:
52                                    FnOperand::Regular(FnPtr {
53                                        kind: box FnPtrKind::Fun(FunId::Regular(fun_id)),
54                                        ..
55                                    }),
56                                ..
57                            },
58                        ..
59                    } = &block.terminator.kind
60                        && panic_fns.contains(fun_id)
61                    {
62                        block.terminator.kind = panic_terminator.clone();
63                    }
64                }
65            }
66        });
67
68        // Remove these functions from the context.
69        for id in &panic_fns {
70            ctx.translated.fun_decls.remove(*id);
71        }
72    }
73}
charon_lib/transform/resugar/inline_local_panic_functions.rs

charon_lib/transform/resugar/
inline_local_panic_functions.rs
