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

rustc_public/mir/
body.rs
