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    /// Computes a value as described by the operation.
591    NullaryOp(NullOp, Ty),
592
593    /// Exactly like `BinaryOp`, but less operands.
594    ///
595    /// Also does two's-complement arithmetic. Negation requires a signed integer or a float;
596    /// bitwise not requires a signed integer, unsigned integer, or bool. Both operation kinds
597    /// return a value with the same type as their operand.
598    UnaryOp(UnOp, Operand),
599
600    /// Yields the operand unchanged
601    Use(Operand),
602}
603
604impl Rvalue {
605    pub fn ty(&self, locals: &[LocalDecl]) -> Result<Ty, Error> {
606        match self {
607            Rvalue::Use(operand) => operand.ty(locals),
608            Rvalue::Repeat(operand, count) => {
609                Ok(Ty::new_array_with_const_len(operand.ty(locals)?, count.clone()))
610            }
611            Rvalue::ThreadLocalRef(did) => Ok(did.ty()),
612            Rvalue::Ref(reg, bk, place) => {
613                let place_ty = place.ty(locals)?;
614                Ok(Ty::new_ref(reg.clone(), place_ty, bk.to_mutable_lossy()))
615            }
616            Rvalue::AddressOf(mutability, place) => {
617                let place_ty = place.ty(locals)?;
618                Ok(Ty::new_ptr(place_ty, mutability.to_mutable_lossy()))
619            }
620            Rvalue::Len(..) => Ok(Ty::usize_ty()),
621            Rvalue::Cast(.., ty) => Ok(*ty),
622            Rvalue::BinaryOp(op, lhs, rhs) => {
623                let lhs_ty = lhs.ty(locals)?;
624                let rhs_ty = rhs.ty(locals)?;
625                Ok(op.ty(lhs_ty, rhs_ty))
626            }
627            Rvalue::CheckedBinaryOp(op, lhs, rhs) => {
628                let lhs_ty = lhs.ty(locals)?;
629                let rhs_ty = rhs.ty(locals)?;
630                let ty = op.ty(lhs_ty, rhs_ty);
631                Ok(Ty::new_tuple(&[ty, Ty::bool_ty()]))
632            }
633            Rvalue::UnaryOp(op, operand) => {
634                let arg_ty = operand.ty(locals)?;
635                Ok(op.ty(arg_ty))
636            }
637            Rvalue::Discriminant(place) => {
638                let place_ty = place.ty(locals)?;
639                place_ty
640                    .kind()
641                    .discriminant_ty()
642                    .ok_or_else(|| error!("Expected a `RigidTy` but found: {place_ty:?}"))
643            }
644            Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(..), _) => {
645                Ok(Ty::usize_ty())
646            }
647            Rvalue::NullaryOp(NullOp::ContractChecks, _)
648            | Rvalue::NullaryOp(NullOp::UbChecks, _) => Ok(Ty::bool_ty()),
649            Rvalue::Aggregate(ak, ops) => match *ak {
650                AggregateKind::Array(ty) => Ty::try_new_array(ty, ops.len() as u64),
651                AggregateKind::Tuple => Ok(Ty::new_tuple(
652                    &ops.iter().map(|op| op.ty(locals)).collect::<Result<Vec<_>, _>>()?,
653                )),
654                AggregateKind::Adt(def, _, ref args, _, _) => Ok(def.ty_with_args(args)),
655                AggregateKind::Closure(def, ref args) => Ok(Ty::new_closure(def, args.clone())),
656                AggregateKind::Coroutine(def, ref args) => Ok(Ty::new_coroutine(def, args.clone())),
657                AggregateKind::CoroutineClosure(def, ref args) => {
658                    Ok(Ty::new_coroutine_closure(def, args.clone()))
659                }
660                AggregateKind::RawPtr(ty, mutability) => Ok(Ty::new_ptr(ty, mutability)),
661            },
662            Rvalue::ShallowInitBox(_, ty) => Ok(Ty::new_box(*ty)),
663            Rvalue::CopyForDeref(place) => place.ty(locals),
664        }
665    }
666}
667
668#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
669pub enum AggregateKind {
670    Array(Ty),
671    Tuple,
672    Adt(AdtDef, VariantIdx, GenericArgs, Option<UserTypeAnnotationIndex>, Option<FieldIdx>),
673    Closure(ClosureDef, GenericArgs),
674    Coroutine(CoroutineDef, GenericArgs),
675    CoroutineClosure(CoroutineClosureDef, GenericArgs),
676    RawPtr(Ty, Mutability),
677}
678
679#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
680pub enum Operand {
681    Copy(Place),
682    Move(Place),
683    Constant(ConstOperand),
684}
685
686#[derive(Clone, Eq, PartialEq, Hash, Serialize)]
687pub struct Place {
688    pub local: Local,
689    /// projection out of a place (access a field, deref a pointer, etc)
690    pub projection: Vec<ProjectionElem>,
691}
692
693impl From<Local> for Place {
694    fn from(local: Local) -> Self {
695        Place { local, projection: vec![] }
696    }
697}
698
699#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
700pub struct ConstOperand {
701    pub span: Span,
702    pub user_ty: Option<UserTypeAnnotationIndex>,
703    pub const_: MirConst,
704}
705
706/// Debug information pertaining to a user variable.
707#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
708pub struct VarDebugInfo {
709    /// The variable name.
710    pub name: Symbol,
711
712    /// Source info of the user variable, including the scope
713    /// within which the variable is visible (to debuginfo).
714    pub source_info: SourceInfo,
715
716    /// The user variable's data is split across several fragments,
717    /// each described by a `VarDebugInfoFragment`.
718    pub composite: Option<VarDebugInfoFragment>,
719
720    /// Where the data for this user variable is to be found.
721    pub value: VarDebugInfoContents,
722
723    /// When present, indicates what argument number this variable is in the function that it
724    /// originated from (starting from 1). Note, if MIR inlining is enabled, then this is the
725    /// argument number in the original function before it was inlined.
726    pub argument_index: Option<u16>,
727}
728
729impl VarDebugInfo {
730    /// Return a local variable if this info is related to one.
731    pub fn local(&self) -> Option<Local> {
732        match &self.value {
733            VarDebugInfoContents::Place(place) if place.projection.is_empty() => Some(place.local),
734            VarDebugInfoContents::Place(_) | VarDebugInfoContents::Const(_) => None,
735        }
736    }
737
738    /// Return a constant if this info is related to one.
739    pub fn constant(&self) -> Option<&ConstOperand> {
740        match &self.value {
741            VarDebugInfoContents::Place(_) => None,
742            VarDebugInfoContents::Const(const_op) => Some(const_op),
743        }
744    }
745}
746
747pub type SourceScope = u32;
748
749#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
750pub struct SourceInfo {
751    pub span: Span,
752    pub scope: SourceScope,
753}
754
755#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
756pub struct VarDebugInfoFragment {
757    pub ty: Ty,
758    pub projection: Vec<ProjectionElem>,
759}
760
761#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
762pub enum VarDebugInfoContents {
763    Place(Place),
764    Const(ConstOperand),
765}
766
767// In MIR ProjectionElem is parameterized on the second Field argument and the Index argument. This
768// is so it can be used for both Places (for which the projection elements are of type
769// ProjectionElem<Local, Ty>) and user-provided type annotations (for which the projection elements
770// are of type ProjectionElem<(), ()>).
771// In rustc_public's IR we don't need this generality, so we just use ProjectionElem for Places.
772#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
773pub enum ProjectionElem {
774    /// Dereference projections (e.g. `*_1`) project to the address referenced by the base place.
775    Deref,
776
777    /// A field projection (e.g., `f` in `_1.f`) project to a field in the base place. The field is
778    /// referenced by source-order index rather than the name of the field. The fields type is also
779    /// given.
780    Field(FieldIdx, Ty),
781
782    /// Index into a slice/array. The value of the index is computed at runtime using the `V`
783    /// argument.
784    ///
785    /// Note that this does not also dereference, and so it does not exactly correspond to slice
786    /// indexing in Rust. In other words, in the below Rust code:
787    ///
788    /// ```rust
789    /// let x = &[1, 2, 3, 4];
790    /// let i = 2;
791    /// x[i];
792    /// ```
793    ///
794    /// The `x[i]` is turned into a `Deref` followed by an `Index`, not just an `Index`. The same
795    /// thing is true of the `ConstantIndex` and `Subslice` projections below.
796    Index(Local),
797
798    /// Index into a slice/array given by offsets.
799    ///
800    /// These indices are generated by slice patterns. Easiest to explain by example:
801    ///
802    /// ```ignore (illustrative)
803    /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
804    /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
805    /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
806    /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
807    /// ```
808    ConstantIndex {
809        /// index or -index (in Python terms), depending on from_end
810        offset: u64,
811        /// The thing being indexed must be at least this long -- otherwise, the
812        /// projection is UB.
813        ///
814        /// For arrays this is always the exact length.
815        min_length: u64,
816        /// Counting backwards from end? This is always false when indexing an
817        /// array.
818        from_end: bool,
819    },
820
821    /// Projects a slice from the base place.
822    ///
823    /// These indices are generated by slice patterns. If `from_end` is true, this represents
824    /// `slice[from..slice.len() - to]`. Otherwise it represents `array[from..to]`.
825    Subslice {
826        from: u64,
827        to: u64,
828        /// Whether `to` counts from the start or end of the array/slice.
829        from_end: bool,
830    },
831
832    /// "Downcast" to a variant of an enum or a coroutine.
833    Downcast(VariantIdx),
834
835    /// Like an explicit cast from an opaque type to a concrete type, but without
836    /// requiring an intermediate variable.
837    OpaqueCast(Ty),
838}
839
840#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
841pub struct UserTypeProjection {
842    pub base: UserTypeAnnotationIndex,
843
844    pub projection: Opaque,
845}
846
847pub type Local = usize;
848
849pub const RETURN_LOCAL: Local = 0;
850
851/// The source-order index of a field in a variant.
852///
853/// For example, in the following types,
854/// ```ignore(illustrative)
855/// enum Demo1 {
856///    Variant0 { a: bool, b: i32 },
857///    Variant1 { c: u8, d: u64 },
858/// }
859/// struct Demo2 { e: u8, f: u16, g: u8 }
860/// ```
861/// `a`'s `FieldIdx` is `0`,
862/// `b`'s `FieldIdx` is `1`,
863/// `c`'s `FieldIdx` is `0`, and
864/// `g`'s `FieldIdx` is `2`.
865pub type FieldIdx = usize;
866
867type UserTypeAnnotationIndex = usize;
868
869/// The possible branch sites of a [TerminatorKind::SwitchInt].
870#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
871pub struct SwitchTargets {
872    /// The conditional branches where the first element represents the value that guards this
873    /// branch, and the second element is the branch target.
874    branches: Vec<(u128, BasicBlockIdx)>,
875    /// The `otherwise` branch which will be taken in case none of the conditional branches are
876    /// satisfied.
877    otherwise: BasicBlockIdx,
878}
879
880impl SwitchTargets {
881    /// All possible targets including the `otherwise` target.
882    pub fn all_targets(&self) -> Successors {
883        self.branches.iter().map(|(_, target)| *target).chain(Some(self.otherwise)).collect()
884    }
885
886    /// The `otherwise` branch target.
887    pub fn otherwise(&self) -> BasicBlockIdx {
888        self.otherwise
889    }
890
891    /// The conditional targets which are only taken if the pattern matches the given value.
892    pub fn branches(&self) -> impl Iterator<Item = (u128, BasicBlockIdx)> {
893        self.branches.iter().copied()
894    }
895
896    /// The number of targets including `otherwise`.
897    pub fn len(&self) -> usize {
898        self.branches.len() + 1
899    }
900
901    /// Create a new SwitchTargets from the given branches and `otherwise` target.
902    pub fn new(branches: Vec<(u128, BasicBlockIdx)>, otherwise: BasicBlockIdx) -> SwitchTargets {
903        SwitchTargets { branches, otherwise }
904    }
905}
906
907#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
908pub enum BorrowKind {
909    /// Data must be immutable and is aliasable.
910    Shared,
911
912    /// An immutable, aliasable borrow that is discarded after borrow-checking. Can behave either
913    /// like a normal shared borrow or like a special shallow borrow (see [`FakeBorrowKind`]).
914    Fake(FakeBorrowKind),
915
916    /// Data is mutable and not aliasable.
917    Mut {
918        /// `true` if this borrow arose from method-call auto-ref
919        kind: MutBorrowKind,
920    },
921}
922
923impl BorrowKind {
924    pub fn to_mutable_lossy(self) -> Mutability {
925        match self {
926            BorrowKind::Mut { .. } => Mutability::Mut,
927            BorrowKind::Shared => Mutability::Not,
928            // FIXME: There's no type corresponding to a shallow borrow, so use `&` as an approximation.
929            BorrowKind::Fake(_) => Mutability::Not,
930        }
931    }
932}
933
934#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
935pub enum RawPtrKind {
936    Mut,
937    Const,
938    FakeForPtrMetadata,
939}
940
941impl RawPtrKind {
942    pub fn to_mutable_lossy(self) -> Mutability {
943        match self {
944            RawPtrKind::Mut { .. } => Mutability::Mut,
945            RawPtrKind::Const => Mutability::Not,
946            // FIXME: There's no type corresponding to a shallow borrow, so use `&` as an approximation.
947            RawPtrKind::FakeForPtrMetadata => Mutability::Not,
948        }
949    }
950}
951
952#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
953pub enum MutBorrowKind {
954    Default,
955    TwoPhaseBorrow,
956    ClosureCapture,
957}
958
959#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
960pub enum FakeBorrowKind {
961    /// A shared (deep) borrow. Data must be immutable and is aliasable.
962    Deep,
963    /// The immediately borrowed place must be immutable, but projections from
964    /// it don't need to be. This is used to prevent match guards from replacing
965    /// the scrutinee. For example, a fake borrow of `a.b` doesn't
966    /// conflict with a mutable borrow of `a.b.c`.
967    Shallow,
968}
969
970#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Serialize)]
971pub enum Mutability {
972    Not,
973    Mut,
974}
975
976#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
977pub enum Safety {
978    Safe,
979    Unsafe,
980}
981
982#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
983pub enum PointerCoercion {
984    /// Go from a fn-item type to a fn-pointer type.
985    ReifyFnPointer,
986
987    /// Go from a safe fn pointer to an unsafe fn pointer.
988    UnsafeFnPointer,
989
990    /// Go from a non-capturing closure to a fn pointer or an unsafe fn pointer.
991    /// It cannot convert a closure that requires unsafe.
992    ClosureFnPointer(Safety),
993
994    /// Go from a mut raw pointer to a const raw pointer.
995    MutToConstPointer,
996
997    /// Go from `*const [T; N]` to `*const T`
998    ArrayToPointer,
999
1000    /// Unsize a pointer/reference value, e.g., `&[T; n]` to
1001    /// `&[T]`. Note that the source could be a thin or wide pointer.
1002    /// This will do things like convert thin pointers to wide
1003    /// pointers, or convert structs containing thin pointers to
1004    /// structs containing wide pointers, or convert between wide
1005    /// pointers.
1006    Unsize,
1007}
1008
1009#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Serialize)]
1010pub enum CastKind {
1011    // FIXME(smir-rename): rename this to PointerExposeProvenance
1012    PointerExposeAddress,
1013    PointerWithExposedProvenance,
1014    PointerCoercion(PointerCoercion),
1015    IntToInt,
1016    FloatToInt,
1017    FloatToFloat,
1018    IntToFloat,
1019    PtrToPtr,
1020    FnPtrToPtr,
1021    Transmute,
1022    Subtype,
1023}
1024
1025#[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
1026pub enum NullOp {
1027    /// Returns the size of a value of that type.
1028    SizeOf,
1029    /// Returns the minimum alignment of a type.
1030    AlignOf,
1031    /// Returns the offset of a field.
1032    OffsetOf(Vec<(VariantIdx, FieldIdx)>),
1033    /// cfg!(ub_checks), but at codegen time
1034    UbChecks,
1035    /// cfg!(contract_checks), but at codegen time
1036    ContractChecks,
1037}
1038
1039impl Operand {
1040    /// Get the type of an operand relative to the local declaration.
1041    ///
1042    /// In order to retrieve the correct type, the `locals` argument must match the list of all
1043    /// locals from the function body where this operand originates from.
1044    ///
1045    /// Errors indicate a malformed operand or incompatible locals list.
1046    pub fn ty(&self, locals: &[LocalDecl]) -> Result<Ty, Error> {
1047        match self {
1048            Operand::Copy(place) | Operand::Move(place) => place.ty(locals),
1049            Operand::Constant(c) => Ok(c.ty()),
1050        }
1051    }
1052}
1053
1054impl ConstOperand {
1055    pub fn ty(&self) -> Ty {
1056        self.const_.ty()
1057    }
1058}
1059
1060impl Place {
1061    /// Resolve down the chain of projections to get the type referenced at the end of it.
1062    /// E.g.:
1063    /// Calling `ty()` on `var.field` should return the type of `field`.
1064    ///
1065    /// In order to retrieve the correct type, the `locals` argument must match the list of all
1066    /// locals from the function body where this place originates from.
1067    pub fn ty(&self, locals: &[LocalDecl]) -> Result<Ty, Error> {
1068        self.projection.iter().try_fold(locals[self.local].ty, |place_ty, elem| elem.ty(place_ty))
1069    }
1070}
1071
1072impl ProjectionElem {
1073    /// Get the expected type after applying this projection to a given place type.
1074    pub fn ty(&self, place_ty: Ty) -> Result<Ty, Error> {
1075        let ty = place_ty;
1076        match &self {
1077            ProjectionElem::Deref => Self::deref_ty(ty),
1078            ProjectionElem::Field(_idx, fty) => Ok(*fty),
1079            ProjectionElem::Index(_) | ProjectionElem::ConstantIndex { .. } => Self::index_ty(ty),
1080            ProjectionElem::Subslice { from, to, from_end } => {
1081                Self::subslice_ty(ty, *from, *to, *from_end)
1082            }
1083            ProjectionElem::Downcast(_) => Ok(ty),
1084            ProjectionElem::OpaqueCast(ty) => Ok(*ty),
1085        }
1086    }
1087
1088    fn index_ty(ty: Ty) -> Result<Ty, Error> {
1089        ty.kind().builtin_index().ok_or_else(|| error!("Cannot index non-array type: {ty:?}"))
1090    }
1091
1092    fn subslice_ty(ty: Ty, from: u64, to: u64, from_end: bool) -> Result<Ty, Error> {
1093        let ty_kind = ty.kind();
1094        match ty_kind {
1095            TyKind::RigidTy(RigidTy::Slice(..)) => Ok(ty),
1096            TyKind::RigidTy(RigidTy::Array(inner, _)) if !from_end => Ty::try_new_array(
1097                inner,
1098                to.checked_sub(from).ok_or_else(|| error!("Subslice overflow: {from}..{to}"))?,
1099            ),
1100            TyKind::RigidTy(RigidTy::Array(inner, size)) => {
1101                let size = size.eval_target_usize()?;
1102                let len = size - from - to;
1103                Ty::try_new_array(inner, len)
1104            }
1105            _ => Err(Error(format!("Cannot subslice non-array type: `{ty_kind:?}`"))),
1106        }
1107    }
1108
1109    fn deref_ty(ty: Ty) -> Result<Ty, Error> {
1110        let deref_ty = ty
1111            .kind()
1112            .builtin_deref(true)
1113            .ok_or_else(|| error!("Cannot dereference type: {ty:?}"))?;
1114        Ok(deref_ty.ty)
1115    }
1116}
rustc_public/mir/body.rs

rustc_public/mir/
body.rs
