rustc_public/mir/
body.rs

1use std::io;
2
3use serde::Serialize;
4
5use crate::compiler_interface::with;
6use crate::mir::pretty::function_body;
7use crate::ty::{
8    AdtDef, ClosureDef, CoroutineClosureDef, CoroutineDef, GenericArgs, MirConst, Movability,
9    Region, RigidTy, Ty, TyConst, TyKind, VariantIdx,
10};
11use crate::{Error, Opaque, Span, Symbol};
12
13/// The rustc_public's IR representation of a single function.
14#[derive(Clone, Debug, Serialize)]
15pub struct Body {
16    pub blocks: Vec<BasicBlock>,
17
18    /// Declarations of locals within the function.
19    ///
20    /// The first local is the return value pointer, followed by `arg_count`
21    /// locals for the function arguments, followed by any user-declared
22    /// variables and temporaries.
23    pub(super) locals: LocalDecls,
24
25    /// The number of arguments this function takes.
26    pub(super) arg_count: usize,
27
28    /// Debug information pertaining to user variables, including captures.
29    pub var_debug_info: Vec<VarDebugInfo>,
30
31    /// Mark an argument (which must be a tuple) as getting passed as its individual components.
32    ///
33    /// This is used for the "rust-call" ABI such as closures.
34    pub(super) spread_arg: Option<Local>,
35
36    /// The span that covers the entire function body.
37    pub span: Span,
38}
39
40pub type BasicBlockIdx = usize;
41
42impl Body {
43    /// Constructs a `Body`.
44    ///
45    /// A constructor is required to build a `Body` from outside the crate
46    /// because the `arg_count` and `locals` fields are private.
47    pub fn new(
48        blocks: Vec<BasicBlock>,
49        locals: LocalDecls,
50        arg_count: usize,
51        var_debug_info: Vec<VarDebugInfo>,
52        spread_arg: Option<Local>,
53        span: Span,
54    ) -> Self {
55        // If locals doesn't contain enough entries, it can lead to panics in
56        // `ret_local`, `arg_locals`, and `inner_locals`.
57        assert!(
58            locals.len() > arg_count,
59            "A Body must contain at least a local for the return value and each of the function's arguments"
60        );
61        Self { blocks, locals, arg_count, var_debug_info, spread_arg, span }
62    }
63
64    /// Return local that holds this function's return value.
65    pub fn ret_local(&self) -> &LocalDecl {
66        &self.locals[RETURN_LOCAL]
67    }
68
69    /// Locals in `self` that correspond to this function's arguments.
70    pub fn arg_locals(&self) -> &[LocalDecl] {
71        &self.locals[1..][..self.arg_count]
72    }
73
74    /// Inner locals for this function. These are the locals that are
75    /// neither the return local nor the argument locals.
76    pub fn inner_locals(&self) -> &[LocalDecl] {
77        &self.locals[self.arg_count + 1..]
78    }
79
80    /// Returns a mutable reference to the local that holds this function's return value.
81    pub(crate) fn ret_local_mut(&mut self) -> &mut LocalDecl {
82        &mut self.locals[RETURN_LOCAL]
83    }
84
85    /// Returns a mutable slice of locals corresponding to this function's arguments.
86    pub(crate) fn arg_locals_mut(&mut self) -> &mut [LocalDecl] {
87        &mut self.locals[1..][..self.arg_count]
88    }
89
90    /// Returns a mutable slice of inner locals for this function.
91    /// Inner locals are those that are neither the return local nor the argument locals.
92    pub(crate) fn inner_locals_mut(&mut self) -> &mut [LocalDecl] {
93        &mut self.locals[self.arg_count + 1..]
94    }
95
96    /// Convenience function to get all the locals in this function.
97    ///
98    /// Locals are typically accessed via the more specific methods `ret_local`,
99    /// `arg_locals`, and `inner_locals`.
100    pub fn locals(&self) -> &[LocalDecl] {
101        &self.locals
102    }
103
104    /// Get the local declaration for this local.
105    pub fn local_decl(&self, local: Local) -> Option<&LocalDecl> {
106        self.locals.get(local)
107    }
108
109    /// Get an iterator for all local declarations.
110    pub fn local_decls(&self) -> impl Iterator<Item = (Local, &LocalDecl)> {
111        self.locals.iter().enumerate()
112    }
113
114    /// Emit the body using the provided name for the signature.
115    pub fn dump<W: io::Write>(&self, w: &mut W, fn_name: &str) -> io::Result<()> {
116        function_body(w, self, fn_name)
117    }
118
119    pub fn spread_arg(&self) -> Option<Local> {
120        self.spread_arg
121    }
122}
123
124type LocalDecls = Vec<LocalDecl>;
125
126#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
127pub struct LocalDecl {
128    pub ty: Ty,
129    pub span: Span,
130    pub mutability: Mutability,
131}
132
133#[derive(Clone, PartialEq, Eq, Debug, Serialize)]
134pub struct BasicBlock {
135    pub statements: Vec<Statement>,
136    pub terminator: Terminator,
137}
138
139#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
140pub struct Terminator {
141    pub kind: TerminatorKind,
142    pub span: Span,
143}
144
145impl Terminator {
146    pub fn successors(&self) -> Successors {
147        self.kind.successors()
148    }
149}
150
151pub type Successors = Vec<BasicBlockIdx>;
152
153#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
154pub enum TerminatorKind {
155    Goto {
156        target: BasicBlockIdx,
157    },
158    SwitchInt {
159        discr: Operand,
160        targets: SwitchTargets,
161    },
162    Resume,
163    Abort,
164    Return,
165    Unreachable,
166    Drop {
167        place: Place,
168        target: BasicBlockIdx,
169        unwind: UnwindAction,
170    },
171    Call {
172        func: Operand,
173        args: Vec<Operand>,
174        destination: Place,
175        target: Option<BasicBlockIdx>,
176        unwind: UnwindAction,
177    },
178    Assert {
179        cond: Operand,
180        expected: bool,
181        msg: AssertMessage,
182        target: BasicBlockIdx,
183        unwind: UnwindAction,
184    },
185    InlineAsm {
186        template: String,
187        operands: Vec<InlineAsmOperand>,
188        options: String,
189        line_spans: String,
190        destination: Option<BasicBlockIdx>,
191        unwind: UnwindAction,
192    },
193}
194
195impl TerminatorKind {
196    pub fn successors(&self) -> Successors {
197        use self::TerminatorKind::*;
198        match *self {
199            Call { target: Some(t), unwind: UnwindAction::Cleanup(u), .. }
200            | Drop { target: t, unwind: UnwindAction::Cleanup(u), .. }
201            | Assert { target: t, unwind: UnwindAction::Cleanup(u), .. }
202            | InlineAsm { destination: Some(t), unwind: UnwindAction::Cleanup(u), .. } => {
203                vec![t, u]
204            }
205            Goto { target: t }
206            | Call { target: None, unwind: UnwindAction::Cleanup(t), .. }
207            | Call { target: Some(t), unwind: _, .. }
208            | Drop { target: t, unwind: _, .. }
209            | Assert { target: t, unwind: _, .. }
210            | InlineAsm { destination: None, unwind: UnwindAction::Cleanup(t), .. }
211            | InlineAsm { destination: Some(t), unwind: _, .. } => {
212                vec![t]
213            }
214
215            Return
216            | Resume
217            | Abort
218            | Unreachable
219            | Call { target: None, unwind: _, .. }
220            | InlineAsm { destination: None, unwind: _, .. } => {
221                vec![]
222            }
223            SwitchInt { ref targets, .. } => targets.all_targets(),
224        }
225    }
226
227    pub fn unwind(&self) -> Option<&UnwindAction> {
228        match *self {
229            TerminatorKind::Goto { .. }
230            | TerminatorKind::Return
231            | TerminatorKind::Unreachable
232            | TerminatorKind::Resume
233            | TerminatorKind::Abort
234            | TerminatorKind::SwitchInt { .. } => None,
235            TerminatorKind::Call { ref unwind, .. }
236            | TerminatorKind::Assert { ref unwind, .. }
237            | TerminatorKind::Drop { ref unwind, .. }
238            | TerminatorKind::InlineAsm { ref unwind, .. } => Some(unwind),
239        }
240    }
241}
242
243#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
244pub struct InlineAsmOperand {
245    pub in_value: Option<Operand>,
246    pub out_place: Option<Place>,
247    // This field has a raw debug representation of MIR's InlineAsmOperand.
248    // For now we care about place/operand + the rest in a debug format.
249    pub raw_rpr: String,
250}
251
252#[derive(Copy, Clone, Debug, Eq, PartialEq, Serialize)]
253pub enum UnwindAction {
254    Continue,
255    Unreachable,
256    Terminate,
257    Cleanup(BasicBlockIdx),
258}
259
260#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
261pub enum AssertMessage {
262    BoundsCheck { len: Operand, index: Operand },
263    Overflow(BinOp, Operand, Operand),
264    OverflowNeg(Operand),
265    DivisionByZero(Operand),
266    RemainderByZero(Operand),
267    ResumedAfterReturn(CoroutineKind),
268    ResumedAfterPanic(CoroutineKind),
269    ResumedAfterDrop(CoroutineKind),
270    MisalignedPointerDereference { required: Operand, found: Operand },
271    NullPointerDereference,
272    InvalidEnumConstruction(Operand),
273}
274
275impl AssertMessage {
276    pub fn description(&self) -> Result<&'static str, Error> {
277        match self {
278            AssertMessage::Overflow(BinOp::Add, _, _) => Ok("attempt to add with overflow"),
279            AssertMessage::Overflow(BinOp::Sub, _, _) => Ok("attempt to subtract with overflow"),
280            AssertMessage::Overflow(BinOp::Mul, _, _) => Ok("attempt to multiply with overflow"),
281            AssertMessage::Overflow(BinOp::Div, _, _) => Ok("attempt to divide with overflow"),
282            AssertMessage::Overflow(BinOp::Rem, _, _) => {
283                Ok("attempt to calculate the remainder with overflow")
284            }
285            AssertMessage::OverflowNeg(_) => Ok("attempt to negate with overflow"),
286            AssertMessage::Overflow(BinOp::Shr, _, _) => Ok("attempt to shift right with overflow"),
287            AssertMessage::Overflow(BinOp::Shl, _, _) => Ok("attempt to shift left with overflow"),
288            AssertMessage::Overflow(op, _, _) => Err(error!("`{:?}` cannot overflow", op)),
289            AssertMessage::DivisionByZero(_) => Ok("attempt to divide by zero"),
290            AssertMessage::RemainderByZero(_) => {
291                Ok("attempt to calculate the remainder with a divisor of zero")
292            }
293            AssertMessage::ResumedAfterReturn(CoroutineKind::Coroutine(_)) => {
294                Ok("coroutine resumed after completion")
295            }
296            AssertMessage::ResumedAfterReturn(CoroutineKind::Desugared(
297                CoroutineDesugaring::Async,
298                _,
299            )) => Ok("`async fn` resumed after completion"),
300            AssertMessage::ResumedAfterReturn(CoroutineKind::Desugared(
301                CoroutineDesugaring::Gen,
302                _,
303            )) => Ok("`async gen fn` resumed after completion"),
304            AssertMessage::ResumedAfterReturn(CoroutineKind::Desugared(
305                CoroutineDesugaring::AsyncGen,
306                _,
307            )) => Ok("`gen fn` should just keep returning `AssertMessage::None` after completion"),
308            AssertMessage::ResumedAfterPanic(CoroutineKind::Coroutine(_)) => {
309                Ok("coroutine resumed after panicking")
310            }
311            AssertMessage::ResumedAfterPanic(CoroutineKind::Desugared(
312                CoroutineDesugaring::Async,
313                _,
314            )) => Ok("`async fn` resumed after panicking"),
315            AssertMessage::ResumedAfterPanic(CoroutineKind::Desugared(
316                CoroutineDesugaring::Gen,
317                _,
318            )) => Ok("`async gen fn` resumed after panicking"),
319            AssertMessage::ResumedAfterPanic(CoroutineKind::Desugared(
320                CoroutineDesugaring::AsyncGen,
321                _,
322            )) => Ok("`gen fn` should just keep returning `AssertMessage::None` after panicking"),
323
324            AssertMessage::ResumedAfterDrop(CoroutineKind::Coroutine(_)) => {
325                Ok("coroutine resumed after async drop")
326            }
327            AssertMessage::ResumedAfterDrop(CoroutineKind::Desugared(
328                CoroutineDesugaring::Async,
329                _,
330            )) => Ok("`async fn` resumed after async drop"),
331            AssertMessage::ResumedAfterDrop(CoroutineKind::Desugared(
332                CoroutineDesugaring::Gen,
333                _,
334            )) => Ok("`async gen fn` resumed after async drop"),
335            AssertMessage::ResumedAfterDrop(CoroutineKind::Desugared(
336                CoroutineDesugaring::AsyncGen,
337                _,
338            )) => Ok("`gen fn` should just keep returning `AssertMessage::None` after async drop"),
339
340            AssertMessage::BoundsCheck { .. } => Ok("index out of bounds"),
341            AssertMessage::MisalignedPointerDereference { .. } => {
342                Ok("misaligned pointer dereference")
343            }
344            AssertMessage::NullPointerDereference => Ok("null pointer dereference occurred"),
345            AssertMessage::InvalidEnumConstruction(_) => {
346                Ok("trying to construct an enum from an invalid value")
347            }
348        }
349    }
350}
351
352#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
353pub enum BinOp {
354    Add,
355    AddUnchecked,
356    Sub,
357    SubUnchecked,
358    Mul,
359    MulUnchecked,
360    Div,
361    Rem,
362    BitXor,
363    BitAnd,
364    BitOr,
365    Shl,
366    ShlUnchecked,
367    Shr,
368    ShrUnchecked,
369    Eq,
370    Lt,
371    Le,
372    Ne,
373    Ge,
374    Gt,
375    Cmp,
376    Offset,
377}
378
379impl BinOp {
380    /// Return the type of this operation for the given input Ty.
381    /// This function does not perform type checking, and it currently doesn't handle SIMD.
382    pub fn ty(&self, lhs_ty: Ty, rhs_ty: Ty) -> Ty {
383        with(|ctx| ctx.binop_ty(*self, lhs_ty, rhs_ty))
384    }
385}
386
387#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
388pub enum UnOp {
389    Not,
390    Neg,
391    PtrMetadata,
392}
393
394impl UnOp {
395    /// Return the type of this operation for the given input Ty.
396    /// This function does not perform type checking, and it currently doesn't handle SIMD.
397    pub fn ty(&self, arg_ty: Ty) -> Ty {
398        with(|ctx| ctx.unop_ty(*self, arg_ty))
399    }
400}
401
402#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
403pub enum CoroutineKind {
404    Desugared(CoroutineDesugaring, CoroutineSource),
405    Coroutine(Movability),
406}
407
408#[derive(Copy, Clone, Debug, Eq, PartialEq, Serialize)]
409pub enum CoroutineSource {
410    Block,
411    Closure,
412    Fn,
413}
414
415#[derive(Copy, Clone, Debug, Eq, PartialEq, Serialize)]
416pub enum CoroutineDesugaring {
417    Async,
418
419    Gen,
420
421    AsyncGen,
422}
423
424pub(crate) type LocalDefId = Opaque;
425/// The rustc coverage data structures are heavily tied to internal details of the
426/// coverage implementation that are likely to change, and are unlikely to be
427/// useful to third-party tools for the foreseeable future.
428pub(crate) type Coverage = Opaque;
429
430/// The FakeReadCause describes the type of pattern why a FakeRead statement exists.
431#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
432pub enum FakeReadCause {
433    ForMatchGuard,
434    ForMatchedPlace(LocalDefId),
435    ForGuardBinding,
436    ForLet(LocalDefId),
437    ForIndex,
438}
439
440/// Describes what kind of retag is to be performed
441#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
442pub enum RetagKind {
443    FnEntry,
444    TwoPhase,
445    Raw,
446    Default,
447}
448
449#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
450pub enum Variance {
451    Covariant,
452    Invariant,
453    Contravariant,
454    Bivariant,
455}
456
457#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
458pub struct CopyNonOverlapping {
459    pub src: Operand,
460    pub dst: Operand,
461    pub count: Operand,
462}
463
464#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
465pub enum NonDivergingIntrinsic {
466    Assume(Operand),
467    CopyNonOverlapping(CopyNonOverlapping),
468}
469
470#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
471pub struct Statement {
472    pub kind: StatementKind,
473    pub span: Span,
474}
475
476#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
477pub enum StatementKind {
478    Assign(Place, Rvalue),
479    FakeRead(FakeReadCause, Place),
480    SetDiscriminant { place: Place, variant_index: VariantIdx },
481    StorageLive(Local),
482    StorageDead(Local),
483    Retag(RetagKind, Place),
484    PlaceMention(Place),
485    AscribeUserType { place: Place, projections: UserTypeProjection, variance: Variance },
486    Coverage(Coverage),
487    Intrinsic(NonDivergingIntrinsic),
488    ConstEvalCounter,
489    Nop,
490}
491
492#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
493pub enum Rvalue {
494    /// Creates a pointer with the indicated mutability to the place.
495    ///
496    /// This is generated by pointer casts like `&v as *const _` or raw address of expressions like
497    /// `&raw v` or `addr_of!(v)`.
498    AddressOf(RawPtrKind, Place),
499
500    /// Creates an aggregate value, like a tuple or struct.
501    ///
502    /// This is needed because dataflow analysis needs to distinguish
503    /// `dest = Foo { x: ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case that `Foo`
504    /// has a destructor.
505    ///
506    /// Disallowed after deaggregation for all aggregate kinds except `Array` and `Coroutine`. After
507    /// coroutine lowering, `Coroutine` aggregate kinds are disallowed too.
508    Aggregate(AggregateKind, Vec<Operand>),
509
510    /// * `Offset` has the same semantics as `<*const T>::offset`, except that the second
511    ///   parameter may be a `usize` as well.
512    /// * The comparison operations accept `bool`s, `char`s, signed or unsigned integers, floats,
513    ///   raw pointers, or function pointers and return a `bool`. The types of the operands must be
514    ///   matching, up to the usual caveat of the lifetimes in function pointers.
515    /// * Left and right shift operations accept signed or unsigned integers not necessarily of the
516    ///   same type and return a value of the same type as their LHS. Like in Rust, the RHS is
517    ///   truncated as needed.
518    /// * The `Bit*` operations accept signed integers, unsigned integers, or bools with matching
519    ///   types and return a value of that type.
520    /// * The remaining operations accept signed integers, unsigned integers, or floats with
521    ///   matching types and return a value of that type.
522    BinaryOp(BinOp, Operand, Operand),
523
524    /// Performs essentially all of the casts that can be performed via `as`.
525    ///
526    /// This allows for casts from/to a variety of types.
527    Cast(CastKind, Operand, Ty),
528
529    /// Same as `BinaryOp`, but yields `(T, bool)` with a `bool` indicating an error condition.
530    ///
531    /// For addition, subtraction, and multiplication on integers the error condition is set when
532    /// the infinite precision result would not be equal to the actual result.
533    CheckedBinaryOp(BinOp, Operand, Operand),
534
535    /// A CopyForDeref is equivalent to a read from a place.
536    /// When such a read happens, it is guaranteed that the only use of the returned value is a
537    /// deref operation, immediately followed by one or more projections.
538    CopyForDeref(Place),
539
540    /// Computes the discriminant of the place, returning it as an integer.
541    /// Returns zero for types without discriminant.
542    ///
543    /// The validity requirements for the underlying value are undecided for this rvalue, see
544    /// [#91095]. Note too that the value of the discriminant is not the same thing as the
545    /// variant index;
546    ///
547    /// [#91095]: https://github.com/rust-lang/rust/issues/91095
548    Discriminant(Place),
549
550    /// Yields the length of the place, as a `usize`.
551    ///
552    /// If the type of the place is an array, this is the array length. For slices (`[T]`, not
553    /// `&[T]`) this accesses the place's metadata to determine the length. This rvalue is
554    /// ill-formed for places of other types.
555    Len(Place),
556
557    /// Creates a reference to the place.
558    Ref(Region, BorrowKind, Place),
559
560    /// Creates an array where each element is the value of the operand.
561    ///
562    /// This is the cause of a bug in the case where the repetition count is zero because the value
563    /// is not dropped, see [#74836].
564    ///
565    /// Corresponds to source code like `[x; 32]`.
566    ///
567    /// [#74836]: https://github.com/rust-lang/rust/issues/74836
568    Repeat(Operand, TyConst),
569
570    /// Transmutes a `*mut u8` into shallow-initialized `Box<T>`.
571    ///
572    /// This is different from a normal transmute because dataflow analysis will treat the box as
573    /// initialized but its content as uninitialized. Like other pointer casts, this in general
574    /// affects alias analysis.
575    ShallowInitBox(Operand, Ty),
576
577    /// Creates a pointer/reference to the given thread local.
578    ///
579    /// The yielded type is a `*mut T` if the static is mutable, otherwise if the static is extern a
580    /// `*const T`, and if neither of those apply a `&T`.
581    ///
582    /// **Note:** This is a runtime operation that actually executes code and is in this sense more
583    /// like a function call. Also, eliminating dead stores of this rvalue causes `fn main() {}` to
584    /// SIGILL for some reason that I (JakobDegen) never got a chance to look into.
585    ///
586    /// **Needs clarification**: Are there weird additional semantics here related to the runtime
587    /// nature of this operation?
588    ThreadLocalRef(crate::CrateItem),
589
590    /// Exactly like `BinaryOp`, but less operands.
591    ///
592    /// Also does two's-complement arithmetic. Negation requires a signed integer or a float;
593    /// bitwise not requires a signed integer, unsigned integer, or bool. Both operation kinds
594    /// return a value with the same type as their operand.
595    UnaryOp(UnOp, Operand),
596
597    /// Yields the operand unchanged
598    Use(Operand),
599}
600
601impl Rvalue {
602    pub fn ty(&self, locals: &[LocalDecl]) -> Result<Ty, Error> {
603        match self {
604            Rvalue::Use(operand) => operand.ty(locals),
605            Rvalue::Repeat(operand, count) => {
606                Ok(Ty::new_array_with_const_len(operand.ty(locals)?, count.clone()))
607            }
608            Rvalue::ThreadLocalRef(did) => Ok(did.ty()),
609            Rvalue::Ref(reg, bk, place) => {
610                let place_ty = place.ty(locals)?;
611                Ok(Ty::new_ref(reg.clone(), place_ty, bk.to_mutable_lossy()))
612            }
613            Rvalue::AddressOf(mutability, place) => {
614                let place_ty = place.ty(locals)?;
615                Ok(Ty::new_ptr(place_ty, mutability.to_mutable_lossy()))
616            }
617            Rvalue::Len(..) => Ok(Ty::usize_ty()),
618            Rvalue::Cast(.., ty) => Ok(*ty),
619            Rvalue::BinaryOp(op, lhs, rhs) => {
620                let lhs_ty = lhs.ty(locals)?;
621                let rhs_ty = rhs.ty(locals)?;
622                Ok(op.ty(lhs_ty, rhs_ty))
623            }
624            Rvalue::CheckedBinaryOp(op, lhs, rhs) => {
625                let lhs_ty = lhs.ty(locals)?;
626                let rhs_ty = rhs.ty(locals)?;
627                let ty = op.ty(lhs_ty, rhs_ty);
628                Ok(Ty::new_tuple(&[ty, Ty::bool_ty()]))
629            }
630            Rvalue::UnaryOp(op, operand) => {
631                let arg_ty = operand.ty(locals)?;
632                Ok(op.ty(arg_ty))
633            }
634            Rvalue::Discriminant(place) => {
635                let place_ty = place.ty(locals)?;
636                place_ty
637                    .kind()
638                    .discriminant_ty()
639                    .ok_or_else(|| error!("Expected a `RigidTy` but found: {place_ty:?}"))
640            }
641            Rvalue::Aggregate(ak, ops) => match *ak {
642                AggregateKind::Array(ty) => Ty::try_new_array(ty, ops.len() as u64),
643                AggregateKind::Tuple => Ok(Ty::new_tuple(
644                    &ops.iter().map(|op| op.ty(locals)).collect::<Result<Vec<_>, _>>()?,
645                )),
646                AggregateKind::Adt(def, _, ref args, _, _) => Ok(def.ty_with_args(args)),
647                AggregateKind::Closure(def, ref args) => Ok(Ty::new_closure(def, args.clone())),
648                AggregateKind::Coroutine(def, ref args) => Ok(Ty::new_coroutine(def, args.clone())),
649                AggregateKind::CoroutineClosure(def, ref args) => {
650                    Ok(Ty::new_coroutine_closure(def, args.clone()))
651                }
652                AggregateKind::RawPtr(ty, mutability) => Ok(Ty::new_ptr(ty, mutability)),
653            },
654            Rvalue::ShallowInitBox(_, ty) => Ok(Ty::new_box(*ty)),
655            Rvalue::CopyForDeref(place) => place.ty(locals),
656        }
657    }
658}
659
660#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
661pub enum AggregateKind {
662    Array(Ty),
663    Tuple,
664    Adt(AdtDef, VariantIdx, GenericArgs, Option<UserTypeAnnotationIndex>, Option<FieldIdx>),
665    Closure(ClosureDef, GenericArgs),
666    Coroutine(CoroutineDef, GenericArgs),
667    CoroutineClosure(CoroutineClosureDef, GenericArgs),
668    RawPtr(Ty, Mutability),
669}
670
671#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
672pub enum Operand {
673    Copy(Place),
674    Move(Place),
675    Constant(ConstOperand),
676    RuntimeChecks(RuntimeChecks),
677}
678
679#[derive(Clone, Eq, PartialEq, Hash, Serialize)]
680pub struct Place {
681    pub local: Local,
682    /// projection out of a place (access a field, deref a pointer, etc)
683    pub projection: Vec<ProjectionElem>,
684}
685
686impl From<Local> for Place {
687    fn from(local: Local) -> Self {
688        Place { local, projection: vec![] }
689    }
690}
691
692#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
693pub struct ConstOperand {
694    pub span: Span,
695    pub user_ty: Option<UserTypeAnnotationIndex>,
696    pub const_: MirConst,
697}
698
699#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
700pub enum RuntimeChecks {
701    /// cfg!(ub_checks), but at codegen time
702    UbChecks,
703    /// cfg!(contract_checks), but at codegen time
704    ContractChecks,
705    /// cfg!(overflow_checks), but at codegen time
706    OverflowChecks,
707}
708
709/// Debug information pertaining to a user variable.
710#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
711pub struct VarDebugInfo {
712    /// The variable name.
713    pub name: Symbol,
714
715    /// Source info of the user variable, including the scope
716    /// within which the variable is visible (to debuginfo).
717    pub source_info: SourceInfo,
718
719    /// The user variable's data is split across several fragments,
720    /// each described by a `VarDebugInfoFragment`.
721    pub composite: Option<VarDebugInfoFragment>,
722
723    /// Where the data for this user variable is to be found.
724    pub value: VarDebugInfoContents,
725
726    /// When present, indicates what argument number this variable is in the function that it
727    /// originated from (starting from 1). Note, if MIR inlining is enabled, then this is the
728    /// argument number in the original function before it was inlined.
729    pub argument_index: Option<u16>,
730}
731
732impl VarDebugInfo {
733    /// Return a local variable if this info is related to one.
734    pub fn local(&self) -> Option<Local> {
735        match &self.value {
736            VarDebugInfoContents::Place(place) if place.projection.is_empty() => Some(place.local),
737            VarDebugInfoContents::Place(_) | VarDebugInfoContents::Const(_) => None,
738        }
739    }
740
741    /// Return a constant if this info is related to one.
742    pub fn constant(&self) -> Option<&ConstOperand> {
743        match &self.value {
744            VarDebugInfoContents::Place(_) => None,
745            VarDebugInfoContents::Const(const_op) => Some(const_op),
746        }
747    }
748}
749
750pub type SourceScope = u32;
751
752#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
753pub struct SourceInfo {
754    pub span: Span,
755    pub scope: SourceScope,
756}
757
758#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
759pub struct VarDebugInfoFragment {
760    pub ty: Ty,
761    pub projection: Vec<ProjectionElem>,
762}
763
764#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
765pub enum VarDebugInfoContents {
766    Place(Place),
767    Const(ConstOperand),
768}
769
770// In MIR ProjectionElem is parameterized on the second Field argument and the Index argument. This
771// is so it can be used for both Places (for which the projection elements are of type
772// ProjectionElem<Local, Ty>) and user-provided type annotations (for which the projection elements
773// are of type ProjectionElem<(), ()>).
774// In rustc_public's IR we don't need this generality, so we just use ProjectionElem for Places.
775#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
776pub enum ProjectionElem {
777    /// Dereference projections (e.g. `*_1`) project to the address referenced by the base place.
778    Deref,
779
780    /// A field projection (e.g., `f` in `_1.f`) project to a field in the base place. The field is
781    /// referenced by source-order index rather than the name of the field. The fields type is also
782    /// given.
783    Field(FieldIdx, Ty),
784
785    /// Index into a slice/array. The value of the index is computed at runtime using the `V`
786    /// argument.
787    ///
788    /// Note that this does not also dereference, and so it does not exactly correspond to slice
789    /// indexing in Rust. In other words, in the below Rust code:
790    ///
791    /// ```rust
792    /// let x = &[1, 2, 3, 4];
793    /// let i = 2;
794    /// x[i];
795    /// ```
796    ///
797    /// The `x[i]` is turned into a `Deref` followed by an `Index`, not just an `Index`. The same
798    /// thing is true of the `ConstantIndex` and `Subslice` projections below.
799    Index(Local),
800
801    /// Index into a slice/array given by offsets.
802    ///
803    /// These indices are generated by slice patterns. Easiest to explain by example:
804    ///
805    /// ```ignore (illustrative)
806    /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
807    /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
808    /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
809    /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
810    /// ```
811    ConstantIndex {
812        /// index or -index (in Python terms), depending on from_end
813        offset: u64,
814        /// The thing being indexed must be at least this long -- otherwise, the
815        /// projection is UB.
816        ///
817        /// For arrays this is always the exact length.
818        min_length: u64,
819        /// Counting backwards from end? This is always false when indexing an
820        /// array.
821        from_end: bool,
822    },
823
824    /// Projects a slice from the base place.
825    ///
826    /// These indices are generated by slice patterns. If `from_end` is true, this represents
827    /// `slice[from..slice.len() - to]`. Otherwise it represents `array[from..to]`.
828    Subslice {
829        from: u64,
830        to: u64,
831        /// Whether `to` counts from the start or end of the array/slice.
832        from_end: bool,
833    },
834
835    /// "Downcast" to a variant of an enum or a coroutine.
836    Downcast(VariantIdx),
837
838    /// Like an explicit cast from an opaque type to a concrete type, but without
839    /// requiring an intermediate variable.
840    OpaqueCast(Ty),
841}
842
843#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
844pub struct UserTypeProjection {
845    pub base: UserTypeAnnotationIndex,
846
847    pub projection: Opaque,
848}
849
850pub type Local = usize;
851
852pub const RETURN_LOCAL: Local = 0;
853
854/// The source-order index of a field in a variant.
855///
856/// For example, in the following types,
857/// ```ignore(illustrative)
858/// enum Demo1 {
859///    Variant0 { a: bool, b: i32 },
860///    Variant1 { c: u8, d: u64 },
861/// }
862/// struct Demo2 { e: u8, f: u16, g: u8 }
863/// ```
864/// `a`'s `FieldIdx` is `0`,
865/// `b`'s `FieldIdx` is `1`,
866/// `c`'s `FieldIdx` is `0`, and
867/// `g`'s `FieldIdx` is `2`.
868pub type FieldIdx = usize;
869
870type UserTypeAnnotationIndex = usize;
871
872/// The possible branch sites of a [TerminatorKind::SwitchInt].
873#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
874pub struct SwitchTargets {
875    /// The conditional branches where the first element represents the value that guards this
876    /// branch, and the second element is the branch target.
877    branches: Vec<(u128, BasicBlockIdx)>,
878    /// The `otherwise` branch which will be taken in case none of the conditional branches are
879    /// satisfied.
880    otherwise: BasicBlockIdx,
881}
882
883impl SwitchTargets {
884    /// All possible targets including the `otherwise` target.
885    pub fn all_targets(&self) -> Successors {
886        self.branches.iter().map(|(_, target)| *target).chain(Some(self.otherwise)).collect()
887    }
888
889    /// The `otherwise` branch target.
890    pub fn otherwise(&self) -> BasicBlockIdx {
891        self.otherwise
892    }
893
894    /// The conditional targets which are only taken if the pattern matches the given value.
895    pub fn branches(&self) -> impl Iterator<Item = (u128, BasicBlockIdx)> {
896        self.branches.iter().copied()
897    }
898
899    /// The number of targets including `otherwise`.
900    pub fn len(&self) -> usize {
901        self.branches.len() + 1
902    }
903
904    /// Create a new SwitchTargets from the given branches and `otherwise` target.
905    pub fn new(branches: Vec<(u128, BasicBlockIdx)>, otherwise: BasicBlockIdx) -> SwitchTargets {
906        SwitchTargets { branches, otherwise }
907    }
908}
909
910#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
911pub enum BorrowKind {
912    /// Data must be immutable and is aliasable.
913    Shared,
914
915    /// An immutable, aliasable borrow that is discarded after borrow-checking. Can behave either
916    /// like a normal shared borrow or like a special shallow borrow (see [`FakeBorrowKind`]).
917    Fake(FakeBorrowKind),
918
919    /// Data is mutable and not aliasable.
920    Mut {
921        /// `true` if this borrow arose from method-call auto-ref
922        kind: MutBorrowKind,
923    },
924}
925
926impl BorrowKind {
927    pub fn to_mutable_lossy(self) -> Mutability {
928        match self {
929            BorrowKind::Mut { .. } => Mutability::Mut,
930            BorrowKind::Shared => Mutability::Not,
931            // FIXME: There's no type corresponding to a shallow borrow, so use `&` as an approximation.
932            BorrowKind::Fake(_) => Mutability::Not,
933        }
934    }
935}
936
937#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
938pub enum RawPtrKind {
939    Mut,
940    Const,
941    FakeForPtrMetadata,
942}
943
944impl RawPtrKind {
945    pub fn to_mutable_lossy(self) -> Mutability {
946        match self {
947            RawPtrKind::Mut { .. } => Mutability::Mut,
948            RawPtrKind::Const => Mutability::Not,
949            // FIXME: There's no type corresponding to a shallow borrow, so use `&` as an approximation.
950            RawPtrKind::FakeForPtrMetadata => Mutability::Not,
951        }
952    }
953}
954
955#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
956pub enum MutBorrowKind {
957    Default,
958    TwoPhaseBorrow,
959    ClosureCapture,
960}
961
962#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
963pub enum FakeBorrowKind {
964    /// A shared (deep) borrow. Data must be immutable and is aliasable.
965    Deep,
966    /// The immediately borrowed place must be immutable, but projections from
967    /// it don't need to be. This is used to prevent match guards from replacing
968    /// the scrutinee. For example, a fake borrow of `a.b` doesn't
969    /// conflict with a mutable borrow of `a.b.c`.
970    Shallow,
971}
972
973#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Serialize)]
974pub enum Mutability {
975    Not,
976    Mut,
977}
978
979#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
980pub enum Safety {
981    Safe,
982    Unsafe,
983}
984
985#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
986pub enum PointerCoercion {
987    /// Go from a fn-item type to a fn-pointer type.
988    ReifyFnPointer(Safety),
989
990    /// Go from a safe fn pointer to an unsafe fn pointer.
991    UnsafeFnPointer,
992
993    /// Go from a non-capturing closure to a fn pointer or an unsafe fn pointer.
994    /// It cannot convert a closure that requires unsafe.
995    ClosureFnPointer(Safety),
996
997    /// Go from a mut raw pointer to a const raw pointer.
998    MutToConstPointer,
999
1000    /// Go from `*const [T; N]` to `*const T`
1001    ArrayToPointer,
1002
1003    /// Unsize a pointer/reference value, e.g., `&[T; n]` to
1004    /// `&[T]`. Note that the source could be a thin or wide pointer.
1005    /// This will do things like convert thin pointers to wide
1006    /// pointers, or convert structs containing thin pointers to
1007    /// structs containing wide pointers, or convert between wide
1008    /// pointers.
1009    Unsize,
1010}
1011
1012#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
1013pub enum CastKind {
1014    // FIXME(smir-rename): rename this to PointerExposeProvenance
1015    PointerExposeAddress,
1016    PointerWithExposedProvenance,
1017    PointerCoercion(PointerCoercion),
1018    IntToInt,
1019    FloatToInt,
1020    FloatToFloat,
1021    IntToFloat,
1022    PtrToPtr,
1023    FnPtrToPtr,
1024    Transmute,
1025    Subtype,
1026}
1027
1028impl Operand {
1029    /// Get the type of an operand relative to the local declaration.
1030    ///
1031    /// In order to retrieve the correct type, the `locals` argument must match the list of all
1032    /// locals from the function body where this operand originates from.
1033    ///
1034    /// Errors indicate a malformed operand or incompatible locals list.
1035    pub fn ty(&self, locals: &[LocalDecl]) -> Result<Ty, Error> {
1036        match self {
1037            Operand::Copy(place) | Operand::Move(place) => place.ty(locals),
1038            Operand::Constant(c) => Ok(c.ty()),
1039            Operand::RuntimeChecks(_) => Ok(Ty::bool_ty()),
1040        }
1041    }
1042}
1043
1044impl ConstOperand {
1045    pub fn ty(&self) -> Ty {
1046        self.const_.ty()
1047    }
1048}
1049
1050impl Place {
1051    /// Resolve down the chain of projections to get the type referenced at the end of it.
1052    /// E.g.:
1053    /// Calling `ty()` on `var.field` should return the type of `field`.
1054    ///
1055    /// In order to retrieve the correct type, the `locals` argument must match the list of all
1056    /// locals from the function body where this place originates from.
1057    pub fn ty(&self, locals: &[LocalDecl]) -> Result<Ty, Error> {
1058        self.projection.iter().try_fold(locals[self.local].ty, |place_ty, elem| elem.ty(place_ty))
1059    }
1060}
1061
1062impl ProjectionElem {
1063    /// Get the expected type after applying this projection to a given place type.
1064    pub fn ty(&self, place_ty: Ty) -> Result<Ty, Error> {
1065        let ty = place_ty;
1066        match &self {
1067            ProjectionElem::Deref => Self::deref_ty(ty),
1068            ProjectionElem::Field(_idx, fty) => Ok(*fty),
1069            ProjectionElem::Index(_) | ProjectionElem::ConstantIndex { .. } => Self::index_ty(ty),
1070            ProjectionElem::Subslice { from, to, from_end } => {
1071                Self::subslice_ty(ty, *from, *to, *from_end)
1072            }
1073            ProjectionElem::Downcast(_) => Ok(ty),
1074            ProjectionElem::OpaqueCast(ty) => Ok(*ty),
1075        }
1076    }
1077
1078    fn index_ty(ty: Ty) -> Result<Ty, Error> {
1079        ty.kind().builtin_index().ok_or_else(|| error!("Cannot index non-array type: {ty:?}"))
1080    }
1081
1082    fn subslice_ty(ty: Ty, from: u64, to: u64, from_end: bool) -> Result<Ty, Error> {
1083        let ty_kind = ty.kind();
1084        match ty_kind {
1085            TyKind::RigidTy(RigidTy::Slice(..)) => Ok(ty),
1086            TyKind::RigidTy(RigidTy::Array(inner, _)) if !from_end => Ty::try_new_array(
1087                inner,
1088                to.checked_sub(from).ok_or_else(|| error!("Subslice overflow: {from}..{to}"))?,
1089            ),
1090            TyKind::RigidTy(RigidTy::Array(inner, size)) => {
1091                let size = size.eval_target_usize()?;
1092                let len = size - from - to;
1093                Ty::try_new_array(inner, len)
1094            }
1095            _ => Err(Error(format!("Cannot subslice non-array type: `{ty_kind:?}`"))),
1096        }
1097    }
1098
1099    fn deref_ty(ty: Ty) -> Result<Ty, Error> {
1100        let deref_ty = ty
1101            .kind()
1102            .builtin_deref(true)
1103            .ok_or_else(|| error!("Cannot dereference type: {ty:?}"))?;
1104        Ok(deref_ty.ty)
1105    }
1106}
rustc_public/mir/body.rs

rustc_public/mir/
body.rs
