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

rustc_public/mir/
body.rs
