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 ptr_size = self.t_ctx.translated.target_information.target_pointer_size;
225                let place = match kind {
226                    hax::ProjectionElem::Deref => subplace.project(ProjectionElem::Deref, ty),
227                    hax::ProjectionElem::Field(field_kind) => {
228                        use hax::ProjectionElemFieldKind::*;
229                        let proj_elem = match field_kind {
230                            Tuple(id) => {
231                                let tref = subplace.ty().kind().as_adt().unwrap();
232                                let field_id = translate_field_id(*id);
233                                let proj_kind =
234                                    FieldProjKind::Tuple(tref.generics.types.elem_count());
235                                ProjectionElem::Field(proj_kind, field_id)
236                            }
237                            Adt {
238                                typ: _,
239                                variant,
240                                index,
241                            } => {
242                                let field_id = translate_field_id(*index);
243                                let variant_id = variant.map(translate_variant_id);
244                                let tref = subplace.ty().kind().as_adt().unwrap();
245                                let generics = &tref.generics;
246                                match tref.id {
247                                    TypeId::Adt(type_id) => {
248                                        let proj_kind = FieldProjKind::Adt(type_id, variant_id);
249                                        ProjectionElem::Field(proj_kind, field_id)
250                                    }
251                                    TypeId::Tuple => {
252                                        assert!(generics.regions.is_empty());
253                                        assert!(variant.is_none());
254                                        assert!(generics.const_generics.is_empty());
255                                        let proj_kind =
256                                            FieldProjKind::Tuple(generics.types.elem_count());
257                                        ProjectionElem::Field(proj_kind, field_id)
258                                    }
259                                    TypeId::Builtin(BuiltinTy::Box) => {
260                                        // Some sanity checks
261                                        assert!(generics.regions.is_empty());
262                                        assert!(generics.types.elem_count() == 2);
263                                        assert!(generics.const_generics.is_empty());
264                                        assert!(field_id == FieldId::ZERO);
265                                        // We pretend this is a deref.
266                                        ProjectionElem::Deref
267                                    }
268                                    _ => raise_error!(self, span, "Unexpected field projection"),
269                                }
270                            }
271                            ClosureState(index) => {
272                                let field_id = translate_field_id(*index);
273                                let type_id = *subplace
274                                    .ty
275                                    .kind()
276                                    .as_adt()
277                                    .expect("ClosureState projection should apply to an Adt type")
278                                    .id
279                                    .as_adt()
280                                    .unwrap();
281                                ProjectionElem::Field(FieldProjKind::Adt(type_id, None), field_id)
282                            }
283                        };
284                        subplace.project(proj_elem, ty)
285                    }
286                    hax::ProjectionElem::Index(local) => {
287                        let var_id = self.translate_local(local).unwrap();
288                        let local = self.locals.place_for_var(var_id);
289                        let offset = Operand::Copy(local);
290                        subplace.project(
291                            ProjectionElem::Index {
292                                offset: Box::new(offset),
293                                from_end: false,
294                            },
295                            ty,
296                        )
297                    }
298                    hax::ProjectionElem::Downcast(..) => {
299                        // We view it as a nop (the information from the
300                        // downcast has been propagated to the other
301                        // projection elements by Hax)
302                        subplace
303                    }
304                    &hax::ProjectionElem::ConstantIndex {
305                        offset,
306                        from_end,
307                        min_length: _,
308                    } => {
309                        let offset = Operand::Const(Box::new(
310                            ScalarValue::from_uint(ptr_size, UIntTy::Usize, offset as u128)
311                                .unwrap()
312                                .to_constant(),
313                        ));
314                        subplace.project(
315                            ProjectionElem::Index {
316                                offset: Box::new(offset),
317                                from_end,
318                            },
319                            ty,
320                        )
321                    }
322                    &hax::ProjectionElem::Subslice { from, to, from_end } => {
323                        let from = Operand::Const(Box::new(
324                            ScalarValue::from_uint(ptr_size, UIntTy::Usize, from as u128)
325                                .unwrap()
326                                .to_constant(),
327                        ));
328                        let to = Operand::Const(Box::new(
329                            ScalarValue::from_uint(ptr_size, UIntTy::Usize, to as u128)
330                                .unwrap()
331                                .to_constant(),
332                        ));
333                        subplace.project(
334                            ProjectionElem::Subslice {
335                                from: Box::new(from),
336                                to: Box::new(to),
337                                from_end,
338                            },
339                            ty,
340                        )
341                    }
342                    hax::ProjectionElem::OpaqueCast => {
343                        // Don't know what that is
344                        raise_error!(self, span, "Unexpected ProjectionElem::OpaqueCast");
345                    }
346                };
347
348                // Return
349                Ok(place)
350            }
351        }
352    }
353
354    /// Translate an operand with its type
355    fn translate_operand_with_type(
356        &mut self,
357        span: Span,
358        operand: &hax::Operand,
359    ) -> Result<(Operand, Ty), Error> {
360        trace!();
361        match operand {
362            hax::Operand::Copy(place) => {
363                let p = self.translate_place(span, place)?;
364                let ty = p.ty().clone();
365                Ok((Operand::Copy(p), ty))
366            }
367            hax::Operand::Move(place) => {
368                let p = self.translate_place(span, place)?;
369                let ty = p.ty().clone();
370                Ok((Operand::Move(p), ty))
371            }
372            hax::Operand::Constant(const_op) => match &const_op.kind {
373                hax::ConstOperandKind::Value(constant) => {
374                    let constant = self.translate_constant_expr_to_constant_expr(span, constant)?;
375                    let ty = constant.ty.clone();
376                    Ok((Operand::Const(Box::new(constant)), ty))
377                }
378                hax::ConstOperandKind::Promoted(item) => {
379                    let ty = self.translate_ty(span, &const_op.ty)?;
380                    // A promoted constant that could not be evaluated.
381                    let global_ref = self.translate_global_decl_ref(span, item)?;
382                    let constant = ConstantExpr {
383                        value: RawConstantExpr::Global(global_ref),
384                        ty: ty.clone(),
385                    };
386                    Ok((Operand::Const(Box::new(constant)), ty))
387                }
388            },
389        }
390    }
391
392    /// Translate an operand
393    fn translate_operand(&mut self, span: Span, operand: &hax::Operand) -> Result<Operand, Error> {
394        trace!();
395        Ok(self.translate_operand_with_type(span, operand)?.0)
396    }
397
398    /// Translate an rvalue
399    fn translate_rvalue(&mut self, span: Span, rvalue: &hax::Rvalue) -> Result<Rvalue, Error> {
400        match rvalue {
401            hax::Rvalue::Use(operand) => Ok(Rvalue::Use(self.translate_operand(span, operand)?)),
402            hax::Rvalue::CopyForDeref(place) => {
403                // According to the documentation, it seems to be an optimisation
404                // for drop elaboration. We treat it as a regular copy.
405                let place = self.translate_place(span, place)?;
406                Ok(Rvalue::Use(Operand::Copy(place)))
407            }
408            hax::Rvalue::Repeat(operand, cnst) => {
409                let c = self.translate_constant_expr_to_const_generic(span, cnst)?;
410                let (operand, t) = self.translate_operand_with_type(span, operand)?;
411                // Remark: we could desugar this into a function call later.
412                Ok(Rvalue::Repeat(operand, t, c))
413            }
414            hax::Rvalue::Ref(_region, borrow_kind, place) => {
415                let place = self.translate_place(span, place)?;
416                let borrow_kind = translate_borrow_kind(*borrow_kind);
417                Ok(Rvalue::Ref(place, borrow_kind))
418            }
419            hax::Rvalue::RawPtr(mtbl, place) => {
420                let mtbl = match mtbl {
421                    hax::RawPtrKind::Mut => RefKind::Mut,
422                    hax::RawPtrKind::Const => RefKind::Shared,
423                    hax::RawPtrKind::FakeForPtrMetadata => RefKind::Shared,
424                };
425                let place = self.translate_place(span, place)?;
426                Ok(Rvalue::RawPtr(place, mtbl))
427            }
428            hax::Rvalue::Len(place) => {
429                let place = self.translate_place(span, place)?;
430                let ty = place.ty().clone();
431                let tref = ty.as_adt().unwrap();
432                let cg = match tref.id {
433                    TypeId::Builtin(BuiltinTy::Array) => {
434                        Some(tref.generics.const_generics[0].clone())
435                    }
436                    TypeId::Builtin(BuiltinTy::Slice) => None,
437                    _ => unreachable!(),
438                };
439                Ok(Rvalue::Len(place, ty, cg))
440            }
441            hax::Rvalue::Cast(cast_kind, hax_operand, tgt_ty) => {
442                trace!("Rvalue::Cast: {:?}", rvalue);
443                // Translate the target type
444                let tgt_ty = self.translate_ty(span, tgt_ty)?;
445
446                // Translate the operand
447                let (mut operand, src_ty) = self.translate_operand_with_type(span, hax_operand)?;
448
449                let cast_kind = match cast_kind {
450                    hax::CastKind::IntToInt
451                    | hax::CastKind::IntToFloat
452                    | hax::CastKind::FloatToInt
453                    | hax::CastKind::FloatToFloat => {
454                        let tgt_ty = *tgt_ty.kind().as_literal().unwrap();
455                        let src_ty = *src_ty.kind().as_literal().unwrap();
456                        CastKind::Scalar(src_ty, tgt_ty)
457                    }
458                    hax::CastKind::PtrToPtr
459                    | hax::CastKind::PointerCoercion(hax::PointerCoercion::MutToConstPointer, ..)
460                    | hax::CastKind::PointerCoercion(hax::PointerCoercion::ArrayToPointer, ..)
461                    | hax::CastKind::FnPtrToPtr
462                    | hax::CastKind::PointerExposeProvenance
463                    | hax::CastKind::PointerWithExposedProvenance => {
464                        CastKind::RawPtr(src_ty, tgt_ty)
465                    }
466                    hax::CastKind::PointerCoercion(
467                        hax::PointerCoercion::ClosureFnPointer(_),
468                        ..,
469                    ) => {
470                        // We model casts of closures to function pointers by generating a new
471                        // function item without the closure's state, that calls the actual closure.
472                        let op_ty = match hax_operand {
473                            hax::Operand::Move(p) | hax::Operand::Copy(p) => p.ty.kind(),
474                            hax::Operand::Constant(c) => c.ty.kind(),
475                        };
476                        let hax::TyKind::Closure(closure) = op_ty else {
477                            unreachable!("Non-closure type in PointerCoercion::ClosureFnPointer");
478                        };
479                        let fn_ref = self.translate_stateless_closure_as_fn_ref(span, closure)?;
480                        let fn_ptr_bound = fn_ref.map(FunDeclRef::into);
481                        let fn_ptr: FnPtr = fn_ptr_bound.clone().erase();
482                        let src_ty = TyKind::FnDef(fn_ptr_bound).into_ty();
483                        operand = Operand::Const(Box::new(ConstantExpr {
484                            value: RawConstantExpr::FnPtr(fn_ptr),
485                            ty: src_ty.clone(),
486                        }));
487                        CastKind::FnPtr(src_ty, tgt_ty)
488                    }
489                    hax::CastKind::PointerCoercion(
490                        hax::PointerCoercion::UnsafeFnPointer
491                        | hax::PointerCoercion::ReifyFnPointer,
492                        ..,
493                    ) => CastKind::FnPtr(src_ty, tgt_ty),
494                    hax::CastKind::Transmute => CastKind::Transmute(src_ty, tgt_ty),
495                    hax::CastKind::PointerCoercion(hax::PointerCoercion::Unsize(meta), ..) => {
496                        let meta = match meta {
497                            hax::UnsizingMetadata::Length(len) => {
498                                let len =
499                                    self.translate_constant_expr_to_const_generic(span, len)?;
500                                UnsizingMetadata::Length(len)
501                            }
502                            hax::UnsizingMetadata::VTablePtr(impl_expr) => {
503                                let tref = self.translate_trait_impl_expr(span, impl_expr)?;
504                                match &impl_expr.r#impl {
505                                    hax::ImplExprAtom::Concrete(tref) => {
506                                        // Ensure the vtable type is translated.
507                                        let _: GlobalDeclId = self.register_item(
508                                            span,
509                                            tref,
510                                            TransItemSourceKind::VTableInstance(
511                                                TraitImplSource::Normal,
512                                            ),
513                                        );
514                                    }
515                                    // TODO(dyn): more ways of registering vtable instance?
516                                    _ => {
517                                        trace!(
518                                            "impl_expr not triggering registering vtable: {:?}",
519                                            impl_expr
520                                        )
521                                    }
522                                };
523                                UnsizingMetadata::VTablePtr(tref)
524                            }
525                            hax::UnsizingMetadata::Unknown => UnsizingMetadata::Unknown,
526                        };
527                        CastKind::Unsize(src_ty.clone(), tgt_ty.clone(), meta)
528                    }
529                };
530                let unop = UnOp::Cast(cast_kind);
531                Ok(Rvalue::UnaryOp(unop, operand))
532            }
533            hax::Rvalue::BinaryOp(binop, (left, right)) => Ok(Rvalue::BinaryOp(
534                self.translate_binaryop_kind(span, *binop)?,
535                self.translate_operand(span, left)?,
536                self.translate_operand(span, right)?,
537            )),
538            hax::Rvalue::NullaryOp(nullop, ty) => {
539                trace!("NullOp: {:?}", nullop);
540                let ty = self.translate_ty(span, ty)?;
541                let op = match nullop {
542                    hax::NullOp::SizeOf => NullOp::SizeOf,
543                    hax::NullOp::AlignOf => NullOp::AlignOf,
544                    hax::NullOp::OffsetOf(fields) => NullOp::OffsetOf(
545                        fields
546                            .iter()
547                            .copied()
548                            .map(|(n, idx)| (n, translate_field_id(idx)))
549                            .collect(),
550                    ),
551                    hax::NullOp::UbChecks => NullOp::UbChecks,
552                    hax::NullOp::ContractChecks => {
553                        raise_error!(self, span, "charon does not support contracts");
554                    }
555                };
556                Ok(Rvalue::NullaryOp(op, ty))
557            }
558            hax::Rvalue::UnaryOp(unop, operand) => {
559                let unop = match unop {
560                    hax::UnOp::Not => UnOp::Not,
561                    hax::UnOp::Neg => UnOp::Neg(OverflowMode::Wrap),
562                    hax::UnOp::PtrMetadata => UnOp::PtrMetadata,
563                };
564                Ok(Rvalue::UnaryOp(
565                    unop,
566                    self.translate_operand(span, operand)?,
567                ))
568            }
569            hax::Rvalue::Discriminant(place) => {
570                let place = self.translate_place(span, place)?;
571                // We should always know the enum type; it can't be a generic.
572                if !place
573                    .ty()
574                    .kind()
575                    .as_adt()
576                    .is_some_and(|tref| tref.id.is_adt())
577                {
578                    raise_error!(
579                        self,
580                        span,
581                        "Unexpected scrutinee type for ReadDiscriminant: {}",
582                        place.ty().with_ctx(&self.into_fmt())
583                    )
584                }
585                Ok(Rvalue::Discriminant(place))
586            }
587            hax::Rvalue::Aggregate(aggregate_kind, operands) => {
588                // It seems this instruction is not present in certain passes:
589                // for example, it seems it is not used in optimized MIR, where
590                // ADT initialization is split into several instructions, for
591                // instance:
592                // ```
593                // p = Pair { x:xv, y:yv };
594                // ```
595                // Might become:
596                // ```
597                // p.x = x;
598                // p.y = yv;
599                // ```
600
601                // First translate the operands
602                let operands_t: Vec<Operand> = operands
603                    .raw
604                    .iter()
605                    .map(|op| self.translate_operand(span, op))
606                    .try_collect()?;
607                let ptr_size = self.t_ctx.translated.target_information.target_pointer_size;
608
609                match aggregate_kind {
610                    hax::AggregateKind::Array(ty) => {
611                        let t_ty = self.translate_ty(span, ty)?;
612                        let cg = ConstGeneric::Value(Literal::Scalar(
613                            ScalarValue::from_uint(
614                                ptr_size,
615                                UIntTy::Usize,
616                                operands_t.len() as u128,
617                            )
618                            .unwrap(),
619                        ));
620                        Ok(Rvalue::Aggregate(
621                            AggregateKind::Array(t_ty, cg),
622                            operands_t,
623                        ))
624                    }
625                    hax::AggregateKind::Tuple => {
626                        let tref = TypeDeclRef::new(TypeId::Tuple, GenericArgs::empty());
627                        Ok(Rvalue::Aggregate(
628                            AggregateKind::Adt(tref, None, None),
629                            operands_t,
630                        ))
631                    }
632                    hax::AggregateKind::Adt(
633                        item,
634                        variant_idx,
635                        kind,
636                        _user_annotation,
637                        field_index,
638                    ) => {
639                        use hax::AdtKind;
640                        trace!("{:?}", rvalue);
641
642                        let tref = self.translate_type_decl_ref(span, item)?;
643                        let variant_id = match kind {
644                            AdtKind::Struct | AdtKind::Union => None,
645                            AdtKind::Enum => Some(translate_variant_id(*variant_idx)),
646                        };
647                        let field_id = match kind {
648                            AdtKind::Struct | AdtKind::Enum => None,
649                            AdtKind::Union => Some(translate_field_id(field_index.unwrap())),
650                        };
651
652                        let akind = AggregateKind::Adt(tref, variant_id, field_id);
653                        Ok(Rvalue::Aggregate(akind, operands_t))
654                    }
655                    hax::AggregateKind::Closure(closure_args) => {
656                        trace!(
657                            "Closure:\n\n- def_id: {:?}\n\n- sig:\n{:?}",
658                            closure_args.item.def_id, closure_args.fn_sig
659                        );
660                        let tref = self.translate_closure_type_ref(span, closure_args)?;
661                        let akind = AggregateKind::Adt(tref, None, None);
662                        Ok(Rvalue::Aggregate(akind, operands_t))
663                    }
664                    hax::AggregateKind::RawPtr(ty, is_mut) => {
665                        // TODO: replace with a call to `ptr::from_raw_parts`.
666                        let t_ty = self.translate_ty(span, ty)?;
667                        let mutability = if *is_mut {
668                            RefKind::Mut
669                        } else {
670                            RefKind::Shared
671                        };
672
673                        let akind = AggregateKind::RawPtr(t_ty, mutability);
674
675                        Ok(Rvalue::Aggregate(akind, operands_t))
676                    }
677                    hax::AggregateKind::Coroutine(..)
678                    | hax::AggregateKind::CoroutineClosure(..) => {
679                        raise_error!(self, span, "Coroutines are not supported");
680                    }
681                }
682            }
683            hax::Rvalue::ShallowInitBox(op, ty) => {
684                let op = self.translate_operand(span, op)?;
685                let ty = self.translate_ty(span, ty)?;
686                Ok(Rvalue::ShallowInitBox(op, ty))
687            }
688            hax::Rvalue::ThreadLocalRef(_) => {
689                raise_error!(
690                    self,
691                    span,
692                    "charon does not support thread local references"
693                );
694            }
695            hax::Rvalue::WrapUnsafeBinder { .. } => {
696                raise_error!(
697                    self,
698                    span,
699                    "charon does not support unsafe lifetime binders"
700                );
701            }
702        }
703    }
704
705    /// Translate a statement
706    ///
707    /// We return an option, because we ignore some statements (`Nop`, `StorageLive`...)
708    fn translate_statement(
709        &mut self,
710        body: &hax::MirBody<hax::mir_kinds::Unknown>,
711        statement: &hax::Statement,
712    ) -> Result<Option<Statement>, Error> {
713        trace!("About to translate statement (MIR) {:?}", statement);
714        let span = self
715            .t_ctx
716            .translate_span_from_source_info(&body.source_scopes, &statement.source_info);
717
718        use hax::StatementKind;
719        let t_statement: Option<RawStatement> = match &*statement.kind {
720            StatementKind::Assign((place, rvalue)) => {
721                let t_place = self.translate_place(span, place)?;
722                let t_rvalue = self.translate_rvalue(span, rvalue)?;
723                Some(RawStatement::Assign(t_place, t_rvalue))
724            }
725            StatementKind::SetDiscriminant {
726                place,
727                variant_index,
728            } => {
729                let t_place = self.translate_place(span, place)?;
730                let variant_id = translate_variant_id(*variant_index);
731                Some(RawStatement::SetDiscriminant(t_place, variant_id))
732            }
733            StatementKind::StorageLive(local) => {
734                let var_id = self.translate_local(local).unwrap();
735                Some(RawStatement::StorageLive(var_id))
736            }
737            StatementKind::StorageDead(local) => {
738                let var_id = self.translate_local(local).unwrap();
739                Some(RawStatement::StorageDead(var_id))
740            }
741            StatementKind::Deinit(place) => {
742                let t_place = self.translate_place(span, place)?;
743                Some(RawStatement::Deinit(t_place))
744            }
745            // This asserts the operand true on pain of UB. We treat it like a normal assertion.
746            StatementKind::Intrinsic(hax::NonDivergingIntrinsic::Assume(op)) => {
747                let op = self.translate_operand(span, op)?;
748                Some(RawStatement::Assert(Assert {
749                    cond: op,
750                    expected: true,
751                    on_failure: AbortKind::UndefinedBehavior,
752                }))
753            }
754            StatementKind::Intrinsic(hax::NonDivergingIntrinsic::CopyNonOverlapping(
755                hax::CopyNonOverlapping { src, dst, count },
756            )) => {
757                let src = self.translate_operand(span, src)?;
758                let dst = self.translate_operand(span, dst)?;
759                let count = self.translate_operand(span, count)?;
760                Some(RawStatement::CopyNonOverlapping(Box::new(
761                    CopyNonOverlapping { src, dst, count },
762                )))
763            }
764            // This is for the stacked borrows memory model.
765            StatementKind::Retag(_, _) => None,
766            // These two are only there to make borrow-checking accept less code, and are removed
767            // in later MIRs.
768            StatementKind::FakeRead(..) | StatementKind::PlaceMention(..) => None,
769            // There are user-provided type annotations with no semantic effect (since we get a
770            // fully-typechecked MIR (TODO: this isn't quite true with opaque types, we should
771            // really use promoted MIR)).
772            StatementKind::AscribeUserType(_, _) => None,
773            // Used for coverage instrumentation.
774            StatementKind::Coverage(_) => None,
775            // Used in the interpreter to check that const code doesn't run for too long or even
776            // indefinitely.
777            StatementKind::ConstEvalCounter => None,
778            // Semantically equivalent to `Nop`, used only for rustc lints.
779            StatementKind::BackwardIncompatibleDropHint { .. } => None,
780            StatementKind::Nop => None,
781        };
782
783        // Add the span information
784        Ok(t_statement.map(|kind| Statement::new(span, kind)))
785    }
786
787    /// Translate a terminator
788    fn translate_terminator(
789        &mut self,
790        body: &hax::MirBody<hax::mir_kinds::Unknown>,
791        terminator: &hax::Terminator,
792        statements: &mut Vec<Statement>,
793    ) -> Result<Terminator, Error> {
794        trace!("About to translate terminator (MIR) {:?}", terminator);
795        // Compute the span information beforehand (we might need it to introduce
796        // intermediate statements - we desugar some terminators)
797        let span = self
798            .t_ctx
799            .translate_span_from_source_info(&body.source_scopes, &terminator.source_info);
800
801        // Translate the terminator
802        use hax::TerminatorKind;
803        let t_terminator: RawTerminator = match &terminator.kind {
804            TerminatorKind::Goto { target } => {
805                let target = self.translate_basic_block_id(*target);
806                RawTerminator::Goto { target }
807            }
808            TerminatorKind::SwitchInt {
809                discr,
810                targets,
811                otherwise,
812                ..
813            } => {
814                // Translate the operand which gives the discriminant
815                let (discr, discr_ty) = self.translate_operand_with_type(span, discr)?;
816
817                // Translate the switch targets
818                let targets = self.translate_switch_targets(span, &discr_ty, targets, otherwise)?;
819
820                RawTerminator::Switch { discr, targets }
821            }
822            TerminatorKind::UnwindResume => RawTerminator::UnwindResume,
823            TerminatorKind::UnwindTerminate { .. } => {
824                RawTerminator::Abort(AbortKind::UnwindTerminate)
825            }
826            TerminatorKind::Return => RawTerminator::Return,
827            // A MIR `Unreachable` terminator indicates undefined behavior of the rust abstract
828            // machine.
829            TerminatorKind::Unreachable => RawTerminator::Abort(AbortKind::UndefinedBehavior),
830            TerminatorKind::Drop {
831                place,
832                impl_expr,
833                target,
834                unwind: _, // We consider that panic is an error, and don't model unwinding
835                ..
836            } => {
837                let place = self.translate_place(span, place)?;
838                let tref = self.translate_trait_impl_expr(span, impl_expr)?;
839                statements.push(Statement::new(span, RawStatement::Drop(place, tref)));
840                let target = self.translate_basic_block_id(*target);
841                RawTerminator::Goto { target }
842            }
843            TerminatorKind::Call {
844                fun,
845                args,
846                destination,
847                target,
848                unwind,
849                fn_span: _,
850                ..
851            } => self.translate_function_call(span, fun, args, destination, target, unwind)?,
852            TerminatorKind::Assert {
853                cond,
854                expected,
855                msg: _,
856                target,
857                unwind: _, // We model unwinding as an effet, we don't represent it in control flow
858            } => {
859                let assert = Assert {
860                    cond: self.translate_operand(span, cond)?,
861                    expected: *expected,
862                    on_failure: AbortKind::Panic(None),
863                };
864                statements.push(Statement::new(span, RawStatement::Assert(assert)));
865                let target = self.translate_basic_block_id(*target);
866                RawTerminator::Goto { target }
867            }
868            TerminatorKind::FalseEdge {
869                real_target,
870                imaginary_target,
871            } => {
872                trace!(
873                    "False edge:\n- real target ({:?}):\n{:?}\n- imaginary target ({:?}):\n{:?}",
874                    real_target,
875                    body.basic_blocks.get(*real_target).unwrap(),
876                    imaginary_target,
877                    body.basic_blocks.get(*imaginary_target).unwrap(),
878                );
879
880                // False edges are used to make the borrow checker a bit conservative.
881                // We translate them as Gotos.
882                // Also note that they are used in some passes, and not in some others
883                // (they are present in mir_promoted, but not mir_optimized).
884                let target = self.translate_basic_block_id(*real_target);
885                RawTerminator::Goto { target }
886            }
887            TerminatorKind::FalseUnwind {
888                real_target,
889                unwind: _,
890            } => {
891                // We consider this to be a goto
892                let target = self.translate_basic_block_id(*real_target);
893                RawTerminator::Goto { target }
894            }
895            TerminatorKind::InlineAsm { .. } => {
896                raise_error!(self, span, "Inline assembly is not supported");
897            }
898            TerminatorKind::CoroutineDrop
899            | TerminatorKind::TailCall { .. }
900            | TerminatorKind::Yield { .. } => {
901                raise_error!(self, span, "Unsupported terminator: {:?}", terminator.kind);
902            }
903        };
904
905        // Add the span information
906        Ok(Terminator::new(span, t_terminator))
907    }
908
909    /// Translate switch targets
910    fn translate_switch_targets(
911        &mut self,
912        span: Span,
913        switch_ty: &Ty,
914        targets: &[(hax::ScalarInt, hax::BasicBlock)],
915        otherwise: &hax::BasicBlock,
916    ) -> Result<SwitchTargets, Error> {
917        trace!("targets: {:?}", targets);
918        let switch_ty = *switch_ty.kind().as_literal().unwrap();
919        match switch_ty {
920            LiteralTy::Bool => {
921                assert_eq!(targets.len(), 1);
922                let (val, target) = targets.first().unwrap();
923                // It seems the block targets are inverted
924                assert_eq!(val.data_le_bytes, [0; 16]);
925                let if_block = self.translate_basic_block_id(*otherwise);
926                let then_block = self.translate_basic_block_id(*target);
927                Ok(SwitchTargets::If(if_block, then_block))
928            }
929            LiteralTy::Int(int_ty) => {
930                let targets: Vec<(ScalarValue, BlockId)> = targets
931                    .iter()
932                    .map(|(v, tgt)| {
933                        let v =
934                            ScalarValue::from_le_bytes(IntegerTy::Signed(int_ty), v.data_le_bytes);
935                        let tgt = self.translate_basic_block_id(*tgt);
936                        (v, tgt)
937                    })
938                    .collect();
939                let otherwise = self.translate_basic_block_id(*otherwise);
940                Ok(SwitchTargets::SwitchInt(
941                    IntegerTy::Signed(int_ty),
942                    targets,
943                    otherwise,
944                ))
945            }
946            LiteralTy::UInt(int_ty) => {
947                let targets: Vec<(ScalarValue, BlockId)> = targets
948                    .iter()
949                    .map(|(v, tgt)| {
950                        let v = ScalarValue::from_le_bytes(
951                            IntegerTy::Unsigned(int_ty),
952                            v.data_le_bytes,
953                        );
954                        let tgt = self.translate_basic_block_id(*tgt);
955                        (v, tgt)
956                    })
957                    .collect();
958                let otherwise = self.translate_basic_block_id(*otherwise);
959                Ok(SwitchTargets::SwitchInt(
960                    IntegerTy::Unsigned(int_ty),
961                    targets,
962                    otherwise,
963                ))
964            }
965            _ => raise_error!(self, span, "Can't match on type {switch_ty}"),
966        }
967    }
968
969    /// Translate a function call statement.
970    /// Note that `body` is the body of the function being translated, not of the
971    /// function referenced in the function call: we need it in order to translate
972    /// the blocks we go to after the function call returns.
973    #[allow(clippy::too_many_arguments)]
974    fn translate_function_call(
975        &mut self,
976        span: Span,
977        fun: &hax::FunOperand,
978        args: &Vec<hax::Spanned<hax::Operand>>,
979        destination: &hax::Place,
980        target: &Option<hax::BasicBlock>,
981        unwind: &UnwindAction,
982    ) -> Result<RawTerminator, Error> {
983        trace!();
984        // There are two cases, depending on whether this is a "regular"
985        // call to a top-level function identified by its id, or if we
986        // are using a local function pointer (i.e., the operand is a "move").
987        let lval = self.translate_place(span, destination)?;
988        // Translate the function operand.
989        let fn_operand = match fun {
990            hax::FunOperand::Static(item) => {
991                trace!("func: {:?}", item.def_id);
992                let fun_def = self.hax_def(item)?;
993                let name = self.t_ctx.translate_name(&TransItemSource::polymorphic(
994                    &item.def_id,
995                    TransItemSourceKind::Fun,
996                ))?;
997                let panic_lang_items = &["panic", "panic_fmt", "begin_panic"];
998                let panic_names = &[&["core", "panicking", "assert_failed"], EXPLICIT_PANIC_NAME];
999
1000                if fun_def
1001                    .lang_item
1002                    .as_deref()
1003                    .is_some_and(|lang_it| panic_lang_items.iter().contains(&lang_it))
1004                    || panic_names.iter().any(|panic| name.equals_ref_name(panic))
1005                {
1006                    // If the call is `panic!`, then the target is `None`.
1007                    // I don't know in which other cases it can be `None`.
1008                    assert!(target.is_none());
1009                    // We ignore the arguments
1010                    return Ok(RawTerminator::Abort(AbortKind::Panic(Some(name))));
1011                } else {
1012                    let fn_ptr = self.translate_fn_ptr(span, item)?.erase();
1013                    FnOperand::Regular(fn_ptr)
1014                }
1015            }
1016            hax::FunOperand::DynamicMove(p) => {
1017                // Call to a local function pointer
1018                let p = self.translate_place(span, p)?;
1019
1020                // TODO: we may have a problem here because as we don't
1021                // know which function is being called, we may not be
1022                // able to filter the arguments properly... But maybe
1023                // this is rather an issue for the statement which creates
1024                // the function pointer, by refering to a top-level function
1025                // for instance.
1026                FnOperand::Move(p)
1027            }
1028        };
1029        let args = self.translate_arguments(span, args)?;
1030        let call = Call {
1031            func: fn_operand,
1032            args,
1033            dest: lval,
1034        };
1035
1036        let target = match target {
1037            Some(target) => self.translate_basic_block_id(*target),
1038            None => {
1039                let abort =
1040                    Terminator::new(span, RawTerminator::Abort(AbortKind::UndefinedBehavior));
1041                self.blocks.push(abort.into_block())
1042            }
1043        };
1044        let on_unwind = match unwind {
1045            UnwindAction::Continue => {
1046                let unwind_continue = Terminator::new(span, RawTerminator::UnwindResume);
1047                self.blocks.push(unwind_continue.into_block())
1048            }
1049            UnwindAction::Unreachable => {
1050                let abort =
1051                    Terminator::new(span, RawTerminator::Abort(AbortKind::UndefinedBehavior));
1052                self.blocks.push(abort.into_block())
1053            }
1054            UnwindAction::Terminate(..) => {
1055                let abort = Terminator::new(span, RawTerminator::Abort(AbortKind::UnwindTerminate));
1056                self.blocks.push(abort.into_block())
1057            }
1058            UnwindAction::Cleanup(bb) => self.translate_basic_block_id(*bb),
1059        };
1060        Ok(RawTerminator::Call {
1061            call,
1062            target,
1063            on_unwind,
1064        })
1065    }
1066
1067    /// Evaluate function arguments in a context, and return the list of computed
1068    /// values.
1069    fn translate_arguments(
1070        &mut self,
1071        span: Span,
1072        args: &Vec<hax::Spanned<hax::Operand>>,
1073    ) -> Result<Vec<Operand>, Error> {
1074        let mut t_args: Vec<Operand> = Vec::new();
1075        for arg in args.iter().map(|x| &x.node) {
1076            // Translate
1077            let op = self.translate_operand(span, arg)?;
1078            t_args.push(op);
1079        }
1080        Ok(t_args)
1081    }
1082
1083    /// Gather all the lines that start with `//` inside the given span.
1084    fn translate_body_comments(
1085        &mut self,
1086        source_text: &Option<String>,
1087        charon_span: Span,
1088    ) -> Vec<(usize, Vec<String>)> {
1089        if let Some(body_text) = source_text {
1090            let mut comments = body_text
1091                .lines()
1092                // Iter through the lines of this body in reverse order.
1093                .rev()
1094                .enumerate()
1095                // Compute the absolute line number
1096                .map(|(i, line)| (charon_span.span.end.line - i, line))
1097                // Extract the comment if this line starts with `//`
1098                .map(|(line_nbr, line)| (line_nbr, line.trim_start().strip_prefix("//")))
1099                .peekable()
1100                .batching(|iter| {
1101                    // Get the next line. This is not a comment: it's either the last line of the
1102                    // body or a line that wasn't consumed by `peeking_take_while`.
1103                    let (line_nbr, _first) = iter.next()?;
1104                    // Collect all the comments before this line.
1105                    let mut comments = iter
1106                        // `peeking_take_while` ensures we don't consume a line that returns
1107                        // `false`. It will be consumed by the next round of `batching`.
1108                        .peeking_take_while(|(_, opt_comment)| opt_comment.is_some())
1109                        .map(|(_, opt_comment)| opt_comment.unwrap())
1110                        .map(|s| s.strip_prefix(" ").unwrap_or(s))
1111                        .map(str::to_owned)
1112                        .collect_vec();
1113                    comments.reverse();
1114                    Some((line_nbr, comments))
1115                })
1116                .filter(|(_, comments)| !comments.is_empty())
1117                .collect_vec();
1118            comments.reverse();
1119            comments
1120        } else {
1121            Vec::new()
1122        }
1123    }
1124
1125    /// Translate the MIR body of this definition if it has one.
1126    pub fn translate_def_body(
1127        &mut self,
1128        span: Span,
1129        def: &hax::FullDef,
1130    ) -> Result<Result<Body, Opaque>, Error> {
1131        // Retrieve the body
1132        let Some(body) = self.get_mir(def.this(), span)? else {
1133            return Ok(Err(Opaque));
1134        };
1135        self.translate_body(span, &body, &def.source_text)
1136    }
1137
1138    /// Translate a function body.
1139    pub fn translate_body(
1140        &mut self,
1141        span: Span,
1142        body: &hax::MirBody<hax::mir_kinds::Unknown>,
1143        source_text: &Option<String>,
1144    ) -> Result<Result<Body, Opaque>, Error> {
1145        // Stopgap measure because there are still many panics in charon and hax.
1146        let mut this = panic::AssertUnwindSafe(&mut *self);
1147        let res = panic::catch_unwind(move || this.translate_body_aux(body, source_text));
1148        match res {
1149            Ok(Ok(body)) => Ok(body),
1150            // Translation error
1151            Ok(Err(e)) => Err(e),
1152            Err(_) => {
1153                raise_error!(self, span, "Thread panicked when extracting body.");
1154            }
1155        }
1156    }
1157
1158    fn translate_body_aux(
1159        &mut self,
1160        body: &hax::MirBody<hax::mir_kinds::Unknown>,
1161        source_text: &Option<String>,
1162    ) -> Result<Result<Body, Opaque>, Error> {
1163        // Compute the span information
1164        let span = self.translate_span_from_hax(&body.span);
1165
1166        // Initialize the local variables
1167        trace!("Translating the body locals");
1168        self.locals.arg_count = body.arg_count;
1169        self.translate_body_locals(&body)?;
1170
1171        // Translate the expression body
1172        trace!("Translating the expression body");
1173
1174        // Register the start block
1175        let id = self.translate_basic_block_id(rustc_index::Idx::new(mir::START_BLOCK.as_usize()));
1176        assert!(id == START_BLOCK_ID);
1177
1178        // For as long as there are blocks in the stack, translate them
1179        while let Some(hax_block_id) = self.blocks_stack.pop_front() {
1180            let hax_block = body.basic_blocks.get(hax_block_id).unwrap();
1181            let block_id = self.translate_basic_block_id(hax_block_id);
1182            let block = self.translate_basic_block(&body, hax_block)?;
1183            self.blocks.set_slot(block_id, block);
1184        }
1185
1186        // Create the body
1187        Ok(Ok(Body::Unstructured(ExprBody {
1188            span,
1189            locals: mem::take(&mut self.locals),
1190            body: mem::take(&mut self.blocks),
1191            comments: self.translate_body_comments(source_text, span),
1192        })))
1193    }
1194}
1195
1196impl<'a> IntoFormatter for &'a BodyTransCtx<'_, '_, '_> {
1197    type C = FmtCtx<'a>;
1198    fn into_fmt(self) -> Self::C {
1199        FmtCtx {
1200            locals: Some(&self.locals),
1201            ..self.i_ctx.into_fmt()
1202        }
1203    }
1204}
charon_driver/translate/translate_bodies.rs

charon_driver/translate/
translate_bodies.rs
