charon_driver/translate/
translate_bodies.rs

1//! Translate functions from the rust compiler MIR to our internal representation.
2//! Our internal representation is very close to MIR, but is more convenient for
3//! us to handle, and easier to maintain - rustc's representation can evolve
4//! independently.
5
6use std::collections::HashMap;
7use std::collections::VecDeque;
8use std::mem;
9use std::ops::Deref;
10use std::ops::DerefMut;
11use std::panic;
12
13use super::translate_crate::*;
14use super::translate_ctx::*;
15use charon_lib::ast::*;
16use charon_lib::formatter::FmtCtx;
17use charon_lib::formatter::IntoFormatter;
18use charon_lib::ids::Vector;
19use charon_lib::pretty::FmtWithCtx;
20use charon_lib::ullbc_ast::*;
21use hax_frontend_exporter as hax;
22use hax_frontend_exporter::UnwindAction;
23use itertools::Itertools;
24use rustc_middle::mir;
25
26/// A translation context for function bodies.
27pub(crate) struct BodyTransCtx<'tcx, 'tctx, 'ictx> {
28    /// The translation context for the item.
29    pub i_ctx: &'ictx mut ItemTransCtx<'tcx, 'tctx>,
30
31    /// The (regular) variables in the current function body.
32    pub locals: Locals,
33    /// The map from rust variable indices to translated variables indices.
34    pub locals_map: HashMap<usize, LocalId>,
35    /// The translated blocks.
36    pub blocks: Vector<BlockId, BlockData>,
37    /// The map from rust blocks to translated blocks.
38    /// Note that when translating terminators like DropAndReplace, we might have
39    /// to introduce new blocks which don't appear in the original MIR.
40    pub blocks_map: HashMap<hax::BasicBlock, BlockId>,
41    /// We register the blocks to translate in a stack, so as to avoid
42    /// writing the translation functions as recursive functions. We do
43    /// so because we had stack overflows in the past.
44    pub blocks_stack: VecDeque<hax::BasicBlock>,
45}
46
47impl<'tcx, 'tctx, 'ictx> BodyTransCtx<'tcx, 'tctx, 'ictx> {
48    pub(crate) fn new(i_ctx: &'ictx mut ItemTransCtx<'tcx, 'tctx>) -> Self {
49        BodyTransCtx {
50            i_ctx,
51            locals: Default::default(),
52            locals_map: Default::default(),
53            blocks: Default::default(),
54            blocks_map: Default::default(),
55            blocks_stack: Default::default(),
56        }
57    }
58}
59
60impl<'tcx, 'tctx, 'ictx> Deref for BodyTransCtx<'tcx, 'tctx, 'ictx> {
61    type Target = ItemTransCtx<'tcx, 'tctx>;
62    fn deref(&self) -> &Self::Target {
63        self.i_ctx
64    }
65}
66impl<'tcx, 'tctx, 'ictx> DerefMut for BodyTransCtx<'tcx, 'tctx, 'ictx> {
67    fn deref_mut(&mut self) -> &mut Self::Target {
68        self.i_ctx
69    }
70}
71
72fn translate_variant_id(id: hax::VariantIdx) -> VariantId {
73    VariantId::new(id)
74}
75
76fn translate_field_id(id: hax::FieldIdx) -> FieldId {
77    use rustc_index::Idx;
78    FieldId::new(id.index())
79}
80
81/// Translate a `BorrowKind`
82fn translate_borrow_kind(borrow_kind: hax::BorrowKind) -> BorrowKind {
83    match borrow_kind {
84        hax::BorrowKind::Shared => BorrowKind::Shared,
85        hax::BorrowKind::Mut { kind } => match kind {
86            hax::MutBorrowKind::Default => BorrowKind::Mut,
87            hax::MutBorrowKind::TwoPhaseBorrow => BorrowKind::TwoPhaseMut,
88            hax::MutBorrowKind::ClosureCapture => BorrowKind::UniqueImmutable,
89        },
90        hax::BorrowKind::Fake(hax::FakeBorrowKind::Shallow) => BorrowKind::Shallow,
91        // This one is used only in deref patterns.
92        hax::BorrowKind::Fake(hax::FakeBorrowKind::Deep) => unimplemented!(),
93    }
94}
95
96impl BodyTransCtx<'_, '_, '_> {
97    pub(crate) fn translate_local(&self, local: &hax::Local) -> Option<LocalId> {
98        use rustc_index::Idx;
99        self.locals_map.get(&local.index()).copied()
100    }
101
102    pub(crate) fn push_var(&mut self, rid: usize, ty: Ty, name: Option<String>) {
103        let local_id = self
104            .locals
105            .locals
106            .push_with(|index| Local { index, name, ty });
107        self.locals_map.insert(rid, local_id);
108    }
109
110    fn translate_binaryop_kind(&mut self, _span: Span, binop: hax::BinOp) -> Result<BinOp, Error> {
111        Ok(match binop {
112            hax::BinOp::BitXor => BinOp::BitXor,
113            hax::BinOp::BitAnd => BinOp::BitAnd,
114            hax::BinOp::BitOr => BinOp::BitOr,
115            hax::BinOp::Eq => BinOp::Eq,
116            hax::BinOp::Lt => BinOp::Lt,
117            hax::BinOp::Le => BinOp::Le,
118            hax::BinOp::Ne => BinOp::Ne,
119            hax::BinOp::Ge => BinOp::Ge,
120            hax::BinOp::Gt => BinOp::Gt,
121            hax::BinOp::Add => BinOp::Add(OverflowMode::Wrap),
122            hax::BinOp::AddUnchecked => BinOp::Add(OverflowMode::UB),
123            hax::BinOp::Sub => BinOp::Sub(OverflowMode::Wrap),
124            hax::BinOp::SubUnchecked => BinOp::Sub(OverflowMode::UB),
125            hax::BinOp::Mul => BinOp::Mul(OverflowMode::Wrap),
126            hax::BinOp::MulUnchecked => BinOp::Mul(OverflowMode::UB),
127            hax::BinOp::Div => BinOp::Div(OverflowMode::UB),
128            hax::BinOp::Rem => BinOp::Rem(OverflowMode::UB),
129            hax::BinOp::AddWithOverflow => BinOp::AddChecked,
130            hax::BinOp::SubWithOverflow => BinOp::SubChecked,
131            hax::BinOp::MulWithOverflow => BinOp::MulChecked,
132            hax::BinOp::Shl => BinOp::Shl(OverflowMode::Wrap),
133            hax::BinOp::ShlUnchecked => BinOp::Shl(OverflowMode::UB),
134            hax::BinOp::Shr => BinOp::Shr(OverflowMode::Wrap),
135            hax::BinOp::ShrUnchecked => BinOp::Shr(OverflowMode::UB),
136            hax::BinOp::Cmp => BinOp::Cmp,
137            hax::BinOp::Offset => BinOp::Offset,
138        })
139    }
140
141    /// Translate a function's local variables by adding them in the environment.
142    fn translate_body_locals(
143        &mut self,
144        body: &hax::MirBody<hax::mir_kinds::Unknown>,
145    ) -> Result<(), Error> {
146        // Translate the parameters
147        for (index, var) in body.local_decls.raw.iter().enumerate() {
148            trace!("Translating local of index {} and type {:?}", index, var.ty);
149
150            // Find the name of the variable
151            let name: Option<String> = var.name.clone();
152
153            // Translate the type
154            let span = self.translate_span_from_hax(&var.source_info.span);
155            let ty = self.translate_ty(span, &var.ty)?;
156
157            // Add the variable to the environment
158            self.push_var(index, ty, name);
159        }
160
161        Ok(())
162    }
163
164    /// Translate a basic block id and register it, if it hasn't been done.
165    fn translate_basic_block_id(&mut self, block_id: hax::BasicBlock) -> BlockId {
166        match self.blocks_map.get(&block_id) {
167            Some(id) => *id,
168            // Generate a fresh id - this also registers the block
169            None => {
170                // Push to the stack of blocks awaiting translation
171                self.blocks_stack.push_back(block_id);
172                let id = self.blocks.reserve_slot();
173                // Insert in the map
174                self.blocks_map.insert(block_id, id);
175                id
176            }
177        }
178    }
179
180    fn translate_basic_block(
181        &mut self,
182        body: &hax::MirBody<hax::mir_kinds::Unknown>,
183        block: &hax::BasicBlockData,
184    ) -> Result<BlockData, Error> {
185        // Translate the statements
186        let mut statements = Vec::new();
187        for statement in &block.statements {
188            trace!("statement: {:?}", statement);
189
190            // Some statements might be ignored, hence the optional returned value
191            let opt_statement = self.translate_statement(body, statement)?;
192            if let Some(statement) = opt_statement {
193                statements.push(statement)
194            }
195        }
196
197        // Translate the terminator
198        let terminator = block.terminator.as_ref().unwrap();
199        let terminator = self.translate_terminator(body, terminator, &mut statements)?;
200
201        Ok(BlockData {
202            statements,
203            terminator,
204        })
205    }
206
207    /// Translate a place
208    /// TODO: Hax represents places in a different manner than MIR. We should
209    /// update our representation of places to match the Hax representation.
210    fn translate_place(&mut self, span: Span, place: &hax::Place) -> Result<Place, Error> {
211        match &place.kind {
212            hax::PlaceKind::Local(local) => {
213                let var_id = self.translate_local(local).unwrap();
214                Ok(self.locals.place_for_var(var_id))
215            }
216            hax::PlaceKind::Projection {
217                place: hax_subplace,
218                kind,
219            } => {
220                let ty = self.translate_ty(span, &place.ty)?;
221                // Compute the type of the value *before* projection - we use this
222                // to disambiguate
223                let subplace = self.translate_place(span, hax_subplace)?;
224                let place = match kind {
225                    hax::ProjectionElem::Deref => subplace.project(ProjectionElem::Deref, ty),
226                    hax::ProjectionElem::Field(field_kind) => {
227                        use hax::ProjectionElemFieldKind::*;
228                        let proj_elem = match field_kind {
229                            Tuple(id) => {
230                                let tref = subplace.ty().kind().as_adt().unwrap();
231                                let field_id = translate_field_id(*id);
232                                let proj_kind =
233                                    FieldProjKind::Tuple(tref.generics.types.elem_count());
234                                ProjectionElem::Field(proj_kind, field_id)
235                            }
236                            Adt {
237                                typ: _,
238                                variant,
239                                index,
240                            } => {
241                                let field_id = translate_field_id(*index);
242                                let variant_id = variant.map(translate_variant_id);
243                                let tref = subplace.ty().kind().as_adt().unwrap();
244                                let generics = &tref.generics;
245                                match tref.id {
246                                    TypeId::Adt(type_id) => {
247                                        let proj_kind = FieldProjKind::Adt(type_id, variant_id);
248                                        ProjectionElem::Field(proj_kind, field_id)
249                                    }
250                                    TypeId::Tuple => {
251                                        assert!(generics.regions.is_empty());
252                                        assert!(variant.is_none());
253                                        assert!(generics.const_generics.is_empty());
254                                        let proj_kind =
255                                            FieldProjKind::Tuple(generics.types.elem_count());
256                                        ProjectionElem::Field(proj_kind, field_id)
257                                    }
258                                    TypeId::Builtin(BuiltinTy::Box) => {
259                                        // Some sanity checks
260                                        assert!(generics.regions.is_empty());
261                                        assert!(generics.types.elem_count() == 2);
262                                        assert!(generics.const_generics.is_empty());
263                                        assert!(field_id == FieldId::ZERO);
264                                        // We pretend this is a deref.
265                                        ProjectionElem::Deref
266                                    }
267                                    _ => raise_error!(self, span, "Unexpected field projection"),
268                                }
269                            }
270                            ClosureState(index) => {
271                                let field_id = translate_field_id(*index);
272                                let type_id = *subplace
273                                    .ty
274                                    .kind()
275                                    .as_adt()
276                                    .expect("ClosureState projection should apply to an Adt type")
277                                    .id
278                                    .as_adt()
279                                    .unwrap();
280                                ProjectionElem::Field(FieldProjKind::Adt(type_id, None), field_id)
281                            }
282                        };
283                        subplace.project(proj_elem, ty)
284                    }
285                    hax::ProjectionElem::Index(local) => {
286                        let var_id = self.translate_local(local).unwrap();
287                        let local = self.locals.place_for_var(var_id);
288                        let offset = Operand::Copy(local);
289                        subplace.project(
290                            ProjectionElem::Index {
291                                offset: Box::new(offset),
292                                from_end: false,
293                            },
294                            ty,
295                        )
296                    }
297                    hax::ProjectionElem::Downcast(..) => {
298                        // We view it as a nop (the information from the
299                        // downcast has been propagated to the other
300                        // projection elements by Hax)
301                        subplace
302                    }
303                    &hax::ProjectionElem::ConstantIndex {
304                        offset,
305                        from_end,
306                        min_length: _,
307                    } => {
308                        let offset =
309                            Operand::Const(Box::new(ScalarValue::Usize(offset).to_constant()));
310                        subplace.project(
311                            ProjectionElem::Index {
312                                offset: Box::new(offset),
313                                from_end,
314                            },
315                            ty,
316                        )
317                    }
318                    &hax::ProjectionElem::Subslice { from, to, from_end } => {
319                        let from = Operand::Const(Box::new(ScalarValue::Usize(from).to_constant()));
320                        let to = Operand::Const(Box::new(ScalarValue::Usize(to).to_constant()));
321                        subplace.project(
322                            ProjectionElem::Subslice {
323                                from: Box::new(from),
324                                to: Box::new(to),
325                                from_end,
326                            },
327                            ty,
328                        )
329                    }
330                    hax::ProjectionElem::OpaqueCast => {
331                        // Don't know what that is
332                        raise_error!(self, span, "Unexpected ProjectionElem::OpaqueCast");
333                    }
334                };
335
336                // Return
337                Ok(place)
338            }
339        }
340    }
341
342    /// Translate an operand with its type
343    fn translate_operand_with_type(
344        &mut self,
345        span: Span,
346        operand: &hax::Operand,
347    ) -> Result<(Operand, Ty), Error> {
348        trace!();
349        match operand {
350            hax::Operand::Copy(place) => {
351                let p = self.translate_place(span, place)?;
352                let ty = p.ty().clone();
353                Ok((Operand::Copy(p), ty))
354            }
355            hax::Operand::Move(place) => {
356                let p = self.translate_place(span, place)?;
357                let ty = p.ty().clone();
358                Ok((Operand::Move(p), ty))
359            }
360            hax::Operand::Constant(const_op) => match &const_op.kind {
361                hax::ConstOperandKind::Value(constant) => {
362                    let constant = self.translate_constant_expr_to_constant_expr(span, constant)?;
363                    let ty = constant.ty.clone();
364                    Ok((Operand::Const(Box::new(constant)), ty))
365                }
366                hax::ConstOperandKind::Promoted(item) => {
367                    let ty = self.translate_ty(span, &const_op.ty)?;
368                    // A promoted constant that could not be evaluated.
369                    let global_ref = self.translate_global_decl_ref(span, item)?;
370                    let constant = ConstantExpr {
371                        value: RawConstantExpr::Global(global_ref),
372                        ty: ty.clone(),
373                    };
374                    Ok((Operand::Const(Box::new(constant)), ty))
375                }
376            },
377        }
378    }
379
380    /// Translate an operand
381    fn translate_operand(&mut self, span: Span, operand: &hax::Operand) -> Result<Operand, Error> {
382        trace!();
383        Ok(self.translate_operand_with_type(span, operand)?.0)
384    }
385
386    /// Translate an rvalue
387    fn translate_rvalue(&mut self, span: Span, rvalue: &hax::Rvalue) -> Result<Rvalue, Error> {
388        match rvalue {
389            hax::Rvalue::Use(operand) => Ok(Rvalue::Use(self.translate_operand(span, operand)?)),
390            hax::Rvalue::CopyForDeref(place) => {
391                // According to the documentation, it seems to be an optimisation
392                // for drop elaboration. We treat it as a regular copy.
393                let place = self.translate_place(span, place)?;
394                Ok(Rvalue::Use(Operand::Copy(place)))
395            }
396            hax::Rvalue::Repeat(operand, cnst) => {
397                let c = self.translate_constant_expr_to_const_generic(span, cnst)?;
398                let (operand, t) = self.translate_operand_with_type(span, operand)?;
399                // Remark: we could desugar this into a function call later.
400                Ok(Rvalue::Repeat(operand, t, c))
401            }
402            hax::Rvalue::Ref(_region, borrow_kind, place) => {
403                let place = self.translate_place(span, place)?;
404                let borrow_kind = translate_borrow_kind(*borrow_kind);
405                Ok(Rvalue::Ref(place, borrow_kind))
406            }
407            hax::Rvalue::RawPtr(mtbl, place) => {
408                let mtbl = match mtbl {
409                    hax::RawPtrKind::Mut => RefKind::Mut,
410                    hax::RawPtrKind::Const => RefKind::Shared,
411                    hax::RawPtrKind::FakeForPtrMetadata => RefKind::Shared,
412                };
413                let place = self.translate_place(span, place)?;
414                Ok(Rvalue::RawPtr(place, mtbl))
415            }
416            hax::Rvalue::Len(place) => {
417                let place = self.translate_place(span, place)?;
418                let ty = place.ty().clone();
419                let tref = ty.as_adt().unwrap();
420                let cg = match tref.id {
421                    TypeId::Builtin(BuiltinTy::Array) => {
422                        Some(tref.generics.const_generics[0].clone())
423                    }
424                    TypeId::Builtin(BuiltinTy::Slice) => None,
425                    _ => unreachable!(),
426                };
427                Ok(Rvalue::Len(place, ty, cg))
428            }
429            hax::Rvalue::Cast(cast_kind, hax_operand, tgt_ty) => {
430                trace!("Rvalue::Cast: {:?}", rvalue);
431                // Translate the target type
432                let tgt_ty = self.translate_ty(span, tgt_ty)?;
433
434                // Translate the operand
435                let (mut operand, src_ty) = self.translate_operand_with_type(span, hax_operand)?;
436
437                let cast_kind = match cast_kind {
438                    hax::CastKind::IntToInt
439                    | hax::CastKind::IntToFloat
440                    | hax::CastKind::FloatToInt
441                    | hax::CastKind::FloatToFloat => {
442                        let tgt_ty = *tgt_ty.kind().as_literal().unwrap();
443                        let src_ty = *src_ty.kind().as_literal().unwrap();
444                        CastKind::Scalar(src_ty, tgt_ty)
445                    }
446                    hax::CastKind::PtrToPtr
447                    | hax::CastKind::PointerCoercion(hax::PointerCoercion::MutToConstPointer, ..)
448                    | hax::CastKind::PointerCoercion(hax::PointerCoercion::ArrayToPointer, ..)
449                    | hax::CastKind::FnPtrToPtr
450                    | hax::CastKind::PointerExposeProvenance
451                    | hax::CastKind::PointerWithExposedProvenance => {
452                        CastKind::RawPtr(src_ty, tgt_ty)
453                    }
454                    hax::CastKind::PointerCoercion(
455                        hax::PointerCoercion::ClosureFnPointer(_),
456                        ..,
457                    ) => {
458                        // We model casts of closures to function pointers by generating a new
459                        // function item without the closure's state, that calls the actual closure.
460                        let op_ty = match hax_operand {
461                            hax::Operand::Move(p) | hax::Operand::Copy(p) => p.ty.kind(),
462                            hax::Operand::Constant(c) => c.ty.kind(),
463                        };
464                        let hax::TyKind::Closure(closure) = op_ty else {
465                            unreachable!("Non-closure type in PointerCoercion::ClosureFnPointer");
466                        };
467                        let fn_ref = self.translate_stateless_closure_as_fn_ref(span, closure)?;
468                        let fn_ptr_bound = fn_ref.map(FunDeclRef::into);
469                        let fn_ptr: FnPtr = fn_ptr_bound.clone().erase();
470                        let src_ty = TyKind::FnDef(fn_ptr_bound).into_ty();
471                        operand = Operand::Const(Box::new(ConstantExpr {
472                            value: RawConstantExpr::FnPtr(fn_ptr),
473                            ty: src_ty.clone(),
474                        }));
475                        CastKind::FnPtr(src_ty, tgt_ty)
476                    }
477                    hax::CastKind::PointerCoercion(
478                        hax::PointerCoercion::UnsafeFnPointer
479                        | hax::PointerCoercion::ReifyFnPointer,
480                        ..,
481                    ) => CastKind::FnPtr(src_ty, tgt_ty),
482                    hax::CastKind::Transmute => CastKind::Transmute(src_ty, tgt_ty),
483                    hax::CastKind::PointerCoercion(hax::PointerCoercion::Unsize(meta), ..) => {
484                        let meta = match meta {
485                            hax::UnsizingMetadata::Length(len) => {
486                                let len =
487                                    self.translate_constant_expr_to_const_generic(span, len)?;
488                                UnsizingMetadata::Length(len)
489                            }
490                            hax::UnsizingMetadata::VTablePtr(impl_expr) => {
491                                let tref = self.translate_trait_impl_expr(span, impl_expr)?;
492                                UnsizingMetadata::VTablePtr(tref)
493                            }
494                            hax::UnsizingMetadata::Unknown => UnsizingMetadata::Unknown,
495                        };
496                        CastKind::Unsize(src_ty.clone(), tgt_ty.clone(), meta)
497                    }
498                };
499                let unop = UnOp::Cast(cast_kind);
500                Ok(Rvalue::UnaryOp(unop, operand))
501            }
502            hax::Rvalue::BinaryOp(binop, (left, right)) => Ok(Rvalue::BinaryOp(
503                self.translate_binaryop_kind(span, *binop)?,
504                self.translate_operand(span, left)?,
505                self.translate_operand(span, right)?,
506            )),
507            hax::Rvalue::NullaryOp(nullop, ty) => {
508                trace!("NullOp: {:?}", nullop);
509                let ty = self.translate_ty(span, ty)?;
510                let op = match nullop {
511                    hax::NullOp::SizeOf => NullOp::SizeOf,
512                    hax::NullOp::AlignOf => NullOp::AlignOf,
513                    hax::NullOp::OffsetOf(fields) => NullOp::OffsetOf(
514                        fields
515                            .iter()
516                            .copied()
517                            .map(|(n, idx)| (n, translate_field_id(idx)))
518                            .collect(),
519                    ),
520                    hax::NullOp::UbChecks => NullOp::UbChecks,
521                    hax::NullOp::ContractChecks => {
522                        raise_error!(self, span, "charon does not support contracts");
523                    }
524                };
525                Ok(Rvalue::NullaryOp(op, ty))
526            }
527            hax::Rvalue::UnaryOp(unop, operand) => {
528                let unop = match unop {
529                    hax::UnOp::Not => UnOp::Not,
530                    hax::UnOp::Neg => UnOp::Neg(OverflowMode::Wrap),
531                    hax::UnOp::PtrMetadata => UnOp::PtrMetadata,
532                };
533                Ok(Rvalue::UnaryOp(
534                    unop,
535                    self.translate_operand(span, operand)?,
536                ))
537            }
538            hax::Rvalue::Discriminant(place) => {
539                let place = self.translate_place(span, place)?;
540                // We should always know the enum type; it can't be a generic.
541                if !place
542                    .ty()
543                    .kind()
544                    .as_adt()
545                    .is_some_and(|tref| tref.id.is_adt())
546                {
547                    raise_error!(
548                        self,
549                        span,
550                        "Unexpected scrutinee type for ReadDiscriminant: {}",
551                        place.ty().with_ctx(&self.into_fmt())
552                    )
553                }
554                Ok(Rvalue::Discriminant(place))
555            }
556            hax::Rvalue::Aggregate(aggregate_kind, operands) => {
557                // It seems this instruction is not present in certain passes:
558                // for example, it seems it is not used in optimized MIR, where
559                // ADT initialization is split into several instructions, for
560                // instance:
561                // ```
562                // p = Pair { x:xv, y:yv };
563                // ```
564                // Might become:
565                // ```
566                // p.x = x;
567                // p.y = yv;
568                // ```
569
570                // First translate the operands
571                let operands_t: Vec<Operand> = operands
572                    .raw
573                    .iter()
574                    .map(|op| self.translate_operand(span, op))
575                    .try_collect()?;
576
577                match aggregate_kind {
578                    hax::AggregateKind::Array(ty) => {
579                        let t_ty = self.translate_ty(span, ty)?;
580                        let cg = ConstGeneric::Value(Literal::Scalar(ScalarValue::Usize(
581                            operands_t.len() as u64,
582                        )));
583                        Ok(Rvalue::Aggregate(
584                            AggregateKind::Array(t_ty, cg),
585                            operands_t,
586                        ))
587                    }
588                    hax::AggregateKind::Tuple => {
589                        let tref = TypeDeclRef::new(TypeId::Tuple, GenericArgs::empty());
590                        Ok(Rvalue::Aggregate(
591                            AggregateKind::Adt(tref, None, None),
592                            operands_t,
593                        ))
594                    }
595                    hax::AggregateKind::Adt(
596                        item,
597                        variant_idx,
598                        kind,
599                        _user_annotation,
600                        field_index,
601                    ) => {
602                        use hax::AdtKind;
603                        trace!("{:?}", rvalue);
604
605                        let tref = self.translate_type_decl_ref(span, item)?;
606                        let variant_id = match kind {
607                            AdtKind::Struct | AdtKind::Union => None,
608                            AdtKind::Enum => Some(translate_variant_id(*variant_idx)),
609                        };
610                        let field_id = match kind {
611                            AdtKind::Struct | AdtKind::Enum => None,
612                            AdtKind::Union => Some(translate_field_id(field_index.unwrap())),
613                        };
614
615                        let akind = AggregateKind::Adt(tref, variant_id, field_id);
616                        Ok(Rvalue::Aggregate(akind, operands_t))
617                    }
618                    hax::AggregateKind::Closure(closure_args) => {
619                        trace!(
620                            "Closure:\n\n- def_id: {:?}\n\n- sig:\n{:?}",
621                            closure_args.item.def_id, closure_args.fn_sig
622                        );
623                        let tref = self.translate_closure_type_ref(span, closure_args)?;
624                        let akind = AggregateKind::Adt(tref, None, None);
625                        Ok(Rvalue::Aggregate(akind, operands_t))
626                    }
627                    hax::AggregateKind::RawPtr(ty, is_mut) => {
628                        // TODO: replace with a call to `ptr::from_raw_parts`.
629                        let t_ty = self.translate_ty(span, ty)?;
630                        let mutability = if *is_mut {
631                            RefKind::Mut
632                        } else {
633                            RefKind::Shared
634                        };
635
636                        let akind = AggregateKind::RawPtr(t_ty, mutability);
637
638                        Ok(Rvalue::Aggregate(akind, operands_t))
639                    }
640                    hax::AggregateKind::Coroutine(..)
641                    | hax::AggregateKind::CoroutineClosure(..) => {
642                        raise_error!(self, span, "Coroutines are not supported");
643                    }
644                }
645            }
646            hax::Rvalue::ShallowInitBox(op, ty) => {
647                let op = self.translate_operand(span, op)?;
648                let ty = self.translate_ty(span, ty)?;
649                Ok(Rvalue::ShallowInitBox(op, ty))
650            }
651            hax::Rvalue::ThreadLocalRef(_) => {
652                raise_error!(
653                    self,
654                    span,
655                    "charon does not support thread local references"
656                );
657            }
658            hax::Rvalue::WrapUnsafeBinder { .. } => {
659                raise_error!(
660                    self,
661                    span,
662                    "charon does not support unsafe lifetime binders"
663                );
664            }
665        }
666    }
667
668    /// Translate a statement
669    ///
670    /// We return an option, because we ignore some statements (`Nop`, `StorageLive`...)
671    fn translate_statement(
672        &mut self,
673        body: &hax::MirBody<hax::mir_kinds::Unknown>,
674        statement: &hax::Statement,
675    ) -> Result<Option<Statement>, Error> {
676        trace!("About to translate statement (MIR) {:?}", statement);
677        let span = self
678            .t_ctx
679            .translate_span_from_source_info(&body.source_scopes, &statement.source_info);
680
681        use hax::StatementKind;
682        let t_statement: Option<RawStatement> = match &*statement.kind {
683            StatementKind::Assign((place, rvalue)) => {
684                let t_place = self.translate_place(span, place)?;
685                let t_rvalue = self.translate_rvalue(span, rvalue)?;
686                Some(RawStatement::Assign(t_place, t_rvalue))
687            }
688            StatementKind::SetDiscriminant {
689                place,
690                variant_index,
691            } => {
692                let t_place = self.translate_place(span, place)?;
693                let variant_id = translate_variant_id(*variant_index);
694                Some(RawStatement::SetDiscriminant(t_place, variant_id))
695            }
696            StatementKind::StorageLive(local) => {
697                let var_id = self.translate_local(local).unwrap();
698                Some(RawStatement::StorageLive(var_id))
699            }
700            StatementKind::StorageDead(local) => {
701                let var_id = self.translate_local(local).unwrap();
702                Some(RawStatement::StorageDead(var_id))
703            }
704            StatementKind::Deinit(place) => {
705                let t_place = self.translate_place(span, place)?;
706                Some(RawStatement::Deinit(t_place))
707            }
708            // This asserts the operand true on pain of UB. We treat it like a normal assertion.
709            StatementKind::Intrinsic(hax::NonDivergingIntrinsic::Assume(op)) => {
710                let op = self.translate_operand(span, op)?;
711                Some(RawStatement::Assert(Assert {
712                    cond: op,
713                    expected: true,
714                    on_failure: AbortKind::UndefinedBehavior,
715                }))
716            }
717            StatementKind::Intrinsic(hax::NonDivergingIntrinsic::CopyNonOverlapping(
718                hax::CopyNonOverlapping { src, dst, count },
719            )) => {
720                let src = self.translate_operand(span, src)?;
721                let dst = self.translate_operand(span, dst)?;
722                let count = self.translate_operand(span, count)?;
723                Some(RawStatement::CopyNonOverlapping(Box::new(
724                    CopyNonOverlapping { src, dst, count },
725                )))
726            }
727            // This is for the stacked borrows memory model.
728            StatementKind::Retag(_, _) => None,
729            // These two are only there to make borrow-checking accept less code, and are removed
730            // in later MIRs.
731            StatementKind::FakeRead(..) | StatementKind::PlaceMention(..) => None,
732            // There are user-provided type annotations with no semantic effect (since we get a
733            // fully-typechecked MIR (TODO: this isn't quite true with opaque types, we should
734            // really use promoted MIR)).
735            StatementKind::AscribeUserType(_, _) => None,
736            // Used for coverage instrumentation.
737            StatementKind::Coverage(_) => None,
738            // Used in the interpreter to check that const code doesn't run for too long or even
739            // indefinitely.
740            StatementKind::ConstEvalCounter => None,
741            // Semantically equivalent to `Nop`, used only for rustc lints.
742            StatementKind::BackwardIncompatibleDropHint { .. } => None,
743            StatementKind::Nop => None,
744        };
745
746        // Add the span information
747        Ok(t_statement.map(|kind| Statement::new(span, kind)))
748    }
749
750    /// Translate a terminator
751    fn translate_terminator(
752        &mut self,
753        body: &hax::MirBody<hax::mir_kinds::Unknown>,
754        terminator: &hax::Terminator,
755        statements: &mut Vec<Statement>,
756    ) -> Result<Terminator, Error> {
757        trace!("About to translate terminator (MIR) {:?}", terminator);
758        // Compute the span information beforehand (we might need it to introduce
759        // intermediate statements - we desugar some terminators)
760        let span = self
761            .t_ctx
762            .translate_span_from_source_info(&body.source_scopes, &terminator.source_info);
763
764        // Translate the terminator
765        use hax::TerminatorKind;
766        let t_terminator: RawTerminator = match &terminator.kind {
767            TerminatorKind::Goto { target } => {
768                let target = self.translate_basic_block_id(*target);
769                RawTerminator::Goto { target }
770            }
771            TerminatorKind::SwitchInt {
772                discr,
773                targets,
774                otherwise,
775                ..
776            } => {
777                // Translate the operand which gives the discriminant
778                let (discr, discr_ty) = self.translate_operand_with_type(span, discr)?;
779
780                // Translate the switch targets
781                let targets = self.translate_switch_targets(span, &discr_ty, targets, otherwise)?;
782
783                RawTerminator::Switch { discr, targets }
784            }
785            TerminatorKind::UnwindResume => RawTerminator::UnwindResume,
786            TerminatorKind::UnwindTerminate { .. } => {
787                RawTerminator::Abort(AbortKind::UnwindTerminate)
788            }
789            TerminatorKind::Return => RawTerminator::Return,
790            // A MIR `Unreachable` terminator indicates undefined behavior of the rust abstract
791            // machine.
792            TerminatorKind::Unreachable => RawTerminator::Abort(AbortKind::UndefinedBehavior),
793            TerminatorKind::Drop {
794                place,
795                impl_expr,
796                target,
797                unwind: _, // We consider that panic is an error, and don't model unwinding
798                ..
799            } => {
800                let place = self.translate_place(span, place)?;
801                let tref = self.translate_trait_impl_expr(span, impl_expr)?;
802                statements.push(Statement::new(span, RawStatement::Drop(place, tref)));
803                let target = self.translate_basic_block_id(*target);
804                RawTerminator::Goto { target }
805            }
806            TerminatorKind::Call {
807                fun,
808                args,
809                destination,
810                target,
811                unwind,
812                fn_span: _,
813                ..
814            } => self.translate_function_call(span, fun, args, destination, target, unwind)?,
815            TerminatorKind::Assert {
816                cond,
817                expected,
818                msg: _,
819                target,
820                unwind: _, // We model unwinding as an effet, we don't represent it in control flow
821            } => {
822                let assert = Assert {
823                    cond: self.translate_operand(span, cond)?,
824                    expected: *expected,
825                    on_failure: AbortKind::Panic(None),
826                };
827                statements.push(Statement::new(span, RawStatement::Assert(assert)));
828                let target = self.translate_basic_block_id(*target);
829                RawTerminator::Goto { target }
830            }
831            TerminatorKind::FalseEdge {
832                real_target,
833                imaginary_target,
834            } => {
835                trace!(
836                    "False edge:\n- real target ({:?}):\n{:?}\n- imaginary target ({:?}):\n{:?}",
837                    real_target,
838                    body.basic_blocks.get(*real_target).unwrap(),
839                    imaginary_target,
840                    body.basic_blocks.get(*imaginary_target).unwrap(),
841                );
842
843                // False edges are used to make the borrow checker a bit conservative.
844                // We translate them as Gotos.
845                // Also note that they are used in some passes, and not in some others
846                // (they are present in mir_promoted, but not mir_optimized).
847                let target = self.translate_basic_block_id(*real_target);
848                RawTerminator::Goto { target }
849            }
850            TerminatorKind::FalseUnwind {
851                real_target,
852                unwind: _,
853            } => {
854                // We consider this to be a goto
855                let target = self.translate_basic_block_id(*real_target);
856                RawTerminator::Goto { target }
857            }
858            TerminatorKind::InlineAsm { .. } => {
859                raise_error!(self, span, "Inline assembly is not supported");
860            }
861            TerminatorKind::CoroutineDrop
862            | TerminatorKind::TailCall { .. }
863            | TerminatorKind::Yield { .. } => {
864                raise_error!(self, span, "Unsupported terminator: {:?}", terminator.kind);
865            }
866        };
867
868        // Add the span information
869        Ok(Terminator::new(span, t_terminator))
870    }
871
872    /// Translate switch targets
873    fn translate_switch_targets(
874        &mut self,
875        span: Span,
876        switch_ty: &Ty,
877        targets: &[(hax::ScalarInt, hax::BasicBlock)],
878        otherwise: &hax::BasicBlock,
879    ) -> Result<SwitchTargets, Error> {
880        trace!("targets: {:?}", targets);
881        let switch_ty = *switch_ty.kind().as_literal().unwrap();
882        match switch_ty {
883            LiteralTy::Bool => {
884                assert_eq!(targets.len(), 1);
885                let (val, target) = targets.first().unwrap();
886                // It seems the block targets are inverted
887                assert_eq!(val.data_le_bytes, [0; 16]);
888                let if_block = self.translate_basic_block_id(*otherwise);
889                let then_block = self.translate_basic_block_id(*target);
890                Ok(SwitchTargets::If(if_block, then_block))
891            }
892            LiteralTy::Integer(int_ty) => {
893                let targets: Vec<(ScalarValue, BlockId)> = targets
894                    .iter()
895                    .map(|(v, tgt)| {
896                        let v = ScalarValue::from_le_bytes(int_ty, v.data_le_bytes);
897                        let tgt = self.translate_basic_block_id(*tgt);
898                        Ok((v, tgt))
899                    })
900                    .try_collect()?;
901                let otherwise = self.translate_basic_block_id(*otherwise);
902                Ok(SwitchTargets::SwitchInt(int_ty, targets, otherwise))
903            }
904            _ => raise_error!(self, span, "Can't match on type {switch_ty}"),
905        }
906    }
907
908    /// Translate a function call statement.
909    /// Note that `body` is the body of the function being translated, not of the
910    /// function referenced in the function call: we need it in order to translate
911    /// the blocks we go to after the function call returns.
912    #[allow(clippy::too_many_arguments)]
913    fn translate_function_call(
914        &mut self,
915        span: Span,
916        fun: &hax::FunOperand,
917        args: &Vec<hax::Spanned<hax::Operand>>,
918        destination: &hax::Place,
919        target: &Option<hax::BasicBlock>,
920        unwind: &UnwindAction,
921    ) -> Result<RawTerminator, Error> {
922        trace!();
923        // There are two cases, depending on whether this is a "regular"
924        // call to a top-level function identified by its id, or if we
925        // are using a local function pointer (i.e., the operand is a "move").
926        let lval = self.translate_place(span, destination)?;
927        // Translate the function operand.
928        let fn_operand = match fun {
929            hax::FunOperand::Static(item) => {
930                trace!("func: {:?}", item.def_id);
931                let fun_def = self.hax_def(&item.def_id)?;
932                let fun_src = TransItemSource::new(item.def_id.clone(), TransItemSourceKind::Fun);
933                let name = self.t_ctx.translate_name(&fun_src)?;
934                let panic_lang_items = &["panic", "panic_fmt", "begin_panic"];
935                let panic_names = &[&["core", "panicking", "assert_failed"], EXPLICIT_PANIC_NAME];
936
937                if fun_def
938                    .lang_item
939                    .as_deref()
940                    .is_some_and(|lang_it| panic_lang_items.iter().contains(&lang_it))
941                    || panic_names.iter().any(|panic| name.equals_ref_name(panic))
942                {
943                    // If the call is `panic!`, then the target is `None`.
944                    // I don't know in which other cases it can be `None`.
945                    assert!(target.is_none());
946                    // We ignore the arguments
947                    return Ok(RawTerminator::Abort(AbortKind::Panic(Some(name))));
948                } else {
949                    let fn_ptr = self.translate_fn_ptr(span, item)?.erase();
950                    FnOperand::Regular(fn_ptr)
951                }
952            }
953            hax::FunOperand::DynamicMove(p) => {
954                // Call to a local function pointer
955                let p = self.translate_place(span, p)?;
956
957                // TODO: we may have a problem here because as we don't
958                // know which function is being called, we may not be
959                // able to filter the arguments properly... But maybe
960                // this is rather an issue for the statement which creates
961                // the function pointer, by refering to a top-level function
962                // for instance.
963                FnOperand::Move(p)
964            }
965        };
966        let args = self.translate_arguments(span, args)?;
967        let call = Call {
968            func: fn_operand,
969            args,
970            dest: lval,
971        };
972
973        let target = match target {
974            Some(target) => self.translate_basic_block_id(*target),
975            None => {
976                let abort =
977                    Terminator::new(span, RawTerminator::Abort(AbortKind::UndefinedBehavior));
978                self.blocks.push(abort.into_block())
979            }
980        };
981        let on_unwind = match unwind {
982            UnwindAction::Continue => {
983                let unwind_continue = Terminator::new(span, RawTerminator::UnwindResume);
984                self.blocks.push(unwind_continue.into_block())
985            }
986            UnwindAction::Unreachable => {
987                let abort =
988                    Terminator::new(span, RawTerminator::Abort(AbortKind::UndefinedBehavior));
989                self.blocks.push(abort.into_block())
990            }
991            UnwindAction::Terminate(..) => {
992                let abort = Terminator::new(span, RawTerminator::Abort(AbortKind::UnwindTerminate));
993                self.blocks.push(abort.into_block())
994            }
995            UnwindAction::Cleanup(bb) => self.translate_basic_block_id(*bb),
996        };
997        Ok(RawTerminator::Call {
998            call,
999            target,
1000            on_unwind,
1001        })
1002    }
1003
1004    /// Evaluate function arguments in a context, and return the list of computed
1005    /// values.
1006    fn translate_arguments(
1007        &mut self,
1008        span: Span,
1009        args: &Vec<hax::Spanned<hax::Operand>>,
1010    ) -> Result<Vec<Operand>, Error> {
1011        let mut t_args: Vec<Operand> = Vec::new();
1012        for arg in args.iter().map(|x| &x.node) {
1013            // Translate
1014            let op = self.translate_operand(span, arg)?;
1015            t_args.push(op);
1016        }
1017        Ok(t_args)
1018    }
1019
1020    /// Gather all the lines that start with `//` inside the given span.
1021    fn translate_body_comments(
1022        &mut self,
1023        source_text: &Option<String>,
1024        charon_span: Span,
1025    ) -> Vec<(usize, Vec<String>)> {
1026        if let Some(body_text) = source_text {
1027            let mut comments = body_text
1028                .lines()
1029                // Iter through the lines of this body in reverse order.
1030                .rev()
1031                .enumerate()
1032                // Compute the absolute line number
1033                .map(|(i, line)| (charon_span.span.end.line - i, line))
1034                // Extract the comment if this line starts with `//`
1035                .map(|(line_nbr, line)| (line_nbr, line.trim_start().strip_prefix("//")))
1036                .peekable()
1037                .batching(|iter| {
1038                    // Get the next line. This is not a comment: it's either the last line of the
1039                    // body or a line that wasn't consumed by `peeking_take_while`.
1040                    let (line_nbr, _first) = iter.next()?;
1041                    // Collect all the comments before this line.
1042                    let mut comments = iter
1043                        // `peeking_take_while` ensures we don't consume a line that returns
1044                        // `false`. It will be consumed by the next round of `batching`.
1045                        .peeking_take_while(|(_, opt_comment)| opt_comment.is_some())
1046                        .map(|(_, opt_comment)| opt_comment.unwrap())
1047                        .map(|s| s.strip_prefix(" ").unwrap_or(s))
1048                        .map(str::to_owned)
1049                        .collect_vec();
1050                    comments.reverse();
1051                    Some((line_nbr, comments))
1052                })
1053                .filter(|(_, comments)| !comments.is_empty())
1054                .collect_vec();
1055            comments.reverse();
1056            comments
1057        } else {
1058            Vec::new()
1059        }
1060    }
1061
1062    /// Translate the MIR body of this definition if it has one.
1063    pub fn translate_def_body(
1064        &mut self,
1065        span: Span,
1066        def: &hax::FullDef,
1067    ) -> Result<Result<Body, Opaque>, Error> {
1068        // Retrieve the body
1069        let Some(body) = self.t_ctx.get_mir(&def.def_id, span)? else {
1070            return Ok(Err(Opaque));
1071        };
1072        self.translate_body(span, &body, &def.source_text)
1073    }
1074
1075    /// Translate a function body.
1076    pub fn translate_body(
1077        &mut self,
1078        span: Span,
1079        body: &hax::MirBody<hax::mir_kinds::Unknown>,
1080        source_text: &Option<String>,
1081    ) -> Result<Result<Body, Opaque>, Error> {
1082        // Stopgap measure because there are still many panics in charon and hax.
1083        let mut this = panic::AssertUnwindSafe(&mut *self);
1084        let res = panic::catch_unwind(move || this.translate_body_aux(body, source_text));
1085        match res {
1086            Ok(Ok(body)) => Ok(body),
1087            // Translation error
1088            Ok(Err(e)) => Err(e),
1089            Err(_) => {
1090                raise_error!(self, span, "Thread panicked when extracting body.");
1091            }
1092        }
1093    }
1094
1095    fn translate_body_aux(
1096        &mut self,
1097        body: &hax::MirBody<hax::mir_kinds::Unknown>,
1098        source_text: &Option<String>,
1099    ) -> Result<Result<Body, Opaque>, Error> {
1100        // Compute the span information
1101        let span = self.translate_span_from_hax(&body.span);
1102
1103        // Initialize the local variables
1104        trace!("Translating the body locals");
1105        self.locals.arg_count = body.arg_count;
1106        self.translate_body_locals(&body)?;
1107
1108        // Translate the expression body
1109        trace!("Translating the expression body");
1110
1111        // Register the start block
1112        let id = self.translate_basic_block_id(rustc_index::Idx::new(mir::START_BLOCK.as_usize()));
1113        assert!(id == START_BLOCK_ID);
1114
1115        // For as long as there are blocks in the stack, translate them
1116        while let Some(hax_block_id) = self.blocks_stack.pop_front() {
1117            let hax_block = body.basic_blocks.get(hax_block_id).unwrap();
1118            let block_id = self.translate_basic_block_id(hax_block_id);
1119            let block = self.translate_basic_block(&body, hax_block)?;
1120            self.blocks.set_slot(block_id, block);
1121        }
1122
1123        // Create the body
1124        Ok(Ok(Body::Unstructured(ExprBody {
1125            span,
1126            locals: mem::take(&mut self.locals),
1127            body: mem::take(&mut self.blocks),
1128            comments: self.translate_body_comments(source_text, span),
1129        })))
1130    }
1131}
1132
1133impl<'a> IntoFormatter for &'a BodyTransCtx<'_, '_, '_> {
1134    type C = FmtCtx<'a>;
1135    fn into_fmt(self) -> Self::C {
1136        FmtCtx {
1137            locals: Some(&self.locals),
1138            ..self.i_ctx.into_fmt()
1139        }
1140    }
1141}
charon_driver/translate/translate_bodies.rs

charon_driver/translate/
translate_bodies.rs
