1 //! MIR datatypes and passes. See the [rustc dev guide] for more info.
3 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/mir/index.html
5 use crate::mir::interpret::{
6 AllocRange, ConstAllocation, ConstValue, ErrorHandled, GlobalAlloc, LitToConstInput, Scalar,
8 use crate::mir::visit::MirVisitable;
9 use crate::ty::codec::{TyDecoder, TyEncoder};
10 use crate::ty::fold::{FallibleTypeFolder, TypeFoldable};
11 use crate::ty::print::{FmtPrinter, Printer};
12 use crate::ty::visit::{TypeVisitable, TypeVisitor};
13 use crate::ty::{self, DefIdTree, List, Ty, TyCtxt};
14 use crate::ty::{AdtDef, InstanceDef, ScalarInt, UserTypeAnnotationIndex};
15 use crate::ty::{GenericArg, InternalSubsts, SubstsRef};
17 use rustc_data_structures::captures::Captures;
18 use rustc_errors::ErrorGuaranteed;
19 use rustc_hir::def::{CtorKind, Namespace};
20 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID};
21 use rustc_hir::{self, GeneratorKind, ImplicitSelfKind};
22 use rustc_hir::{self as hir, HirId};
23 use rustc_session::Session;
24 use rustc_target::abi::{Size, VariantIdx};
26 use polonius_engine::Atom;
27 pub use rustc_ast::Mutability;
28 use rustc_data_structures::fx::FxHashSet;
29 use rustc_data_structures::graph::dominators::Dominators;
30 use rustc_index::bit_set::BitMatrix;
31 use rustc_index::vec::{Idx, IndexVec};
32 use rustc_serialize::{Decodable, Encodable};
33 use rustc_span::symbol::Symbol;
34 use rustc_span::{Span, DUMMY_SP};
39 use std::fmt::{self, Debug, Display, Formatter, Write};
40 use std::ops::{ControlFlow, Index, IndexMut};
43 pub use self::query::*;
44 pub use basic_blocks::BasicBlocks;
49 pub mod generic_graphviz;
61 pub use terminator::*;
68 pub use self::generic_graph::graphviz_safe_def_name;
69 pub use self::graphviz::write_mir_graphviz;
70 pub use self::pretty::{
71 create_dump_file, display_allocation, dump_enabled, dump_mir, write_mir_pretty, PassWhere,
75 pub type LocalDecls<'tcx> = IndexVec<Local, LocalDecl<'tcx>>;
77 pub trait HasLocalDecls<'tcx> {
78 fn local_decls(&self) -> &LocalDecls<'tcx>;
81 impl<'tcx> HasLocalDecls<'tcx> for LocalDecls<'tcx> {
83 fn local_decls(&self) -> &LocalDecls<'tcx> {
88 impl<'tcx> HasLocalDecls<'tcx> for Body<'tcx> {
90 fn local_decls(&self) -> &LocalDecls<'tcx> {
95 /// A streamlined trait that you can implement to create a pass; the
96 /// pass will be named after the type, and it will consist of a main
97 /// loop that goes over each available MIR and applies `run_pass`.
98 pub trait MirPass<'tcx> {
99 fn name(&self) -> &str {
100 let name = std::any::type_name::<Self>();
101 if let Some((_, tail)) = name.rsplit_once(':') { tail } else { name }
104 /// Returns `true` if this pass is enabled with the current combination of compiler flags.
105 fn is_enabled(&self, _sess: &Session) -> bool {
109 fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>);
111 fn is_mir_dump_enabled(&self) -> bool {
117 /// Gets the index of the current MirPhase within the set of all `MirPhase`s.
119 /// FIXME(JakobDegen): Return a `(usize, usize)` instead.
120 pub fn phase_index(&self) -> usize {
121 const BUILT_PHASE_COUNT: usize = 1;
122 const ANALYSIS_PHASE_COUNT: usize = 2;
124 MirPhase::Built => 1,
125 MirPhase::Analysis(analysis_phase) => {
126 1 + BUILT_PHASE_COUNT + (*analysis_phase as usize)
128 MirPhase::Runtime(runtime_phase) => {
129 1 + BUILT_PHASE_COUNT + ANALYSIS_PHASE_COUNT + (*runtime_phase as usize)
134 /// Parses an `MirPhase` from a pair of strings. Panics if this isn't possible for any reason.
135 pub fn parse(dialect: String, phase: Option<String>) -> Self {
136 match &*dialect.to_ascii_lowercase() {
138 assert!(phase.is_none(), "Cannot specify a phase for `Built` MIR");
141 "analysis" => Self::Analysis(AnalysisPhase::parse(phase)),
142 "runtime" => Self::Runtime(RuntimePhase::parse(phase)),
143 _ => panic!("Unknown MIR dialect {}", dialect),
149 pub fn parse(phase: Option<String>) -> Self {
150 let Some(phase) = phase else {
151 return Self::Initial;
154 match &*phase.to_ascii_lowercase() {
155 "initial" => Self::Initial,
156 "post_cleanup" | "post-cleanup" | "postcleanup" => Self::PostCleanup,
157 _ => panic!("Unknown analysis phase {}", phase),
163 pub fn parse(phase: Option<String>) -> Self {
164 let Some(phase) = phase else {
165 return Self::Initial;
168 match &*phase.to_ascii_lowercase() {
169 "initial" => Self::Initial,
170 "post_cleanup" | "post-cleanup" | "postcleanup" => Self::PostCleanup,
171 "optimized" => Self::Optimized,
172 _ => panic!("Unknown runtime phase {}", phase),
177 /// Where a specific `mir::Body` comes from.
178 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
179 #[derive(HashStable, TyEncodable, TyDecodable, TypeFoldable, TypeVisitable)]
180 pub struct MirSource<'tcx> {
181 pub instance: InstanceDef<'tcx>,
183 /// If `Some`, this is a promoted rvalue within the parent function.
184 pub promoted: Option<Promoted>,
187 impl<'tcx> MirSource<'tcx> {
188 pub fn item(def_id: DefId) -> Self {
190 instance: InstanceDef::Item(ty::WithOptConstParam::unknown(def_id)),
195 pub fn from_instance(instance: InstanceDef<'tcx>) -> Self {
196 MirSource { instance, promoted: None }
199 pub fn with_opt_param(self) -> ty::WithOptConstParam<DefId> {
200 self.instance.with_opt_param()
204 pub fn def_id(&self) -> DefId {
205 self.instance.def_id()
209 #[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable, TypeVisitable)]
210 pub struct GeneratorInfo<'tcx> {
211 /// The yield type of the function, if it is a generator.
212 pub yield_ty: Option<Ty<'tcx>>,
214 /// Generator drop glue.
215 pub generator_drop: Option<Body<'tcx>>,
217 /// The layout of a generator. Produced by the state transformation.
218 pub generator_layout: Option<GeneratorLayout<'tcx>>,
220 /// If this is a generator then record the type of source expression that caused this generator
222 pub generator_kind: GeneratorKind,
225 /// The lowered representation of a single function.
226 #[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable, TypeVisitable)]
227 pub struct Body<'tcx> {
228 /// A list of basic blocks. References to basic block use a newtyped index type [`BasicBlock`]
229 /// that indexes into this vector.
230 pub basic_blocks: BasicBlocks<'tcx>,
232 /// Records how far through the "desugaring and optimization" process this particular
233 /// MIR has traversed. This is particularly useful when inlining, since in that context
234 /// we instantiate the promoted constants and add them to our promoted vector -- but those
235 /// promoted items have already been optimized, whereas ours have not. This field allows
236 /// us to see the difference and forego optimization on the inlined promoted items.
239 /// How many passses we have executed since starting the current phase. Used for debug output.
240 pub pass_count: usize,
242 pub source: MirSource<'tcx>,
244 /// A list of source scopes; these are referenced by statements
245 /// and used for debuginfo. Indexed by a `SourceScope`.
246 pub source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
248 pub generator: Option<Box<GeneratorInfo<'tcx>>>,
250 /// Declarations of locals.
252 /// The first local is the return value pointer, followed by `arg_count`
253 /// locals for the function arguments, followed by any user-declared
254 /// variables and temporaries.
255 pub local_decls: LocalDecls<'tcx>,
257 /// User type annotations.
258 pub user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
260 /// The number of arguments this function takes.
262 /// Starting at local 1, `arg_count` locals will be provided by the caller
263 /// and can be assumed to be initialized.
265 /// If this MIR was built for a constant, this will be 0.
266 pub arg_count: usize,
268 /// Mark an argument local (which must be a tuple) as getting passed as
269 /// its individual components at the LLVM level.
271 /// This is used for the "rust-call" ABI.
272 pub spread_arg: Option<Local>,
274 /// Debug information pertaining to user variables, including captures.
275 pub var_debug_info: Vec<VarDebugInfo<'tcx>>,
277 /// A span representing this MIR, for error reporting.
280 /// Constants that are required to evaluate successfully for this MIR to be well-formed.
281 /// We hold in this field all the constants we are not able to evaluate yet.
282 pub required_consts: Vec<Constant<'tcx>>,
284 /// Does this body use generic parameters. This is used for the `ConstEvaluatable` check.
286 /// Note that this does not actually mean that this body is not computable right now.
287 /// The repeat count in the following example is polymorphic, but can still be evaluated
288 /// without knowing anything about the type parameter `T`.
292 /// let _ = [0; std::mem::size_of::<*mut T>()];
296 /// **WARNING**: Do not change this flags after the MIR was originally created, even if an optimization
297 /// removed the last mention of all generic params. We do not want to rely on optimizations and
298 /// potentially allow things like `[u8; std::mem::size_of::<T>() * 0]` due to this.
299 pub is_polymorphic: bool,
301 /// The phase at which this MIR should be "injected" into the compilation process.
303 /// Everything that comes before this `MirPhase` should be skipped.
305 /// This is only `Some` if the function that this body comes from was annotated with `rustc_custom_mir`.
306 pub injection_phase: Option<MirPhase>,
308 pub tainted_by_errors: Option<ErrorGuaranteed>,
311 impl<'tcx> Body<'tcx> {
313 source: MirSource<'tcx>,
314 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
315 source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
316 local_decls: LocalDecls<'tcx>,
317 user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
319 var_debug_info: Vec<VarDebugInfo<'tcx>>,
321 generator_kind: Option<GeneratorKind>,
322 tainted_by_errors: Option<ErrorGuaranteed>,
324 // We need `arg_count` locals, and one for the return place.
326 local_decls.len() > arg_count,
327 "expected at least {} locals, got {}",
332 let mut body = Body {
333 phase: MirPhase::Built,
336 basic_blocks: BasicBlocks::new(basic_blocks),
338 generator: generator_kind.map(|generator_kind| {
339 Box::new(GeneratorInfo {
341 generator_drop: None,
342 generator_layout: None,
347 user_type_annotations,
352 required_consts: Vec::new(),
353 is_polymorphic: false,
354 injection_phase: None,
357 body.is_polymorphic = body.has_non_region_param();
361 /// Returns a partially initialized MIR body containing only a list of basic blocks.
363 /// The returned MIR contains no `LocalDecl`s (even for the return place) or source scopes. It
364 /// is only useful for testing but cannot be `#[cfg(test)]` because it is used in a different
366 pub fn new_cfg_only(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>) -> Self {
367 let mut body = Body {
368 phase: MirPhase::Built,
370 source: MirSource::item(CRATE_DEF_ID.to_def_id()),
371 basic_blocks: BasicBlocks::new(basic_blocks),
372 source_scopes: IndexVec::new(),
374 local_decls: IndexVec::new(),
375 user_type_annotations: IndexVec::new(),
379 required_consts: Vec::new(),
380 var_debug_info: Vec::new(),
381 is_polymorphic: false,
382 injection_phase: None,
383 tainted_by_errors: None,
385 body.is_polymorphic = body.has_non_region_param();
390 pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
391 self.basic_blocks.as_mut()
395 pub fn local_kind(&self, local: Local) -> LocalKind {
396 let index = local.as_usize();
399 self.local_decls[local].mutability == Mutability::Mut,
400 "return place should be mutable"
403 LocalKind::ReturnPointer
404 } else if index < self.arg_count + 1 {
406 } else if self.local_decls[local].is_user_variable() {
413 /// Returns an iterator over all user-declared mutable locals.
415 pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + Captures<'tcx> + 'a {
416 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
417 let local = Local::new(index);
418 let decl = &self.local_decls[local];
419 (decl.is_user_variable() && decl.mutability.is_mut()).then(|| local)
423 /// Returns an iterator over all user-declared mutable arguments and locals.
425 pub fn mut_vars_and_args_iter<'a>(
427 ) -> impl Iterator<Item = Local> + Captures<'tcx> + 'a {
428 (1..self.local_decls.len()).filter_map(move |index| {
429 let local = Local::new(index);
430 let decl = &self.local_decls[local];
431 if (decl.is_user_variable() || index < self.arg_count + 1)
432 && decl.mutability == Mutability::Mut
441 /// Returns an iterator over all function arguments.
443 pub fn args_iter(&self) -> impl Iterator<Item = Local> + ExactSizeIterator {
444 (1..self.arg_count + 1).map(Local::new)
447 /// Returns an iterator over all user-defined variables and compiler-generated temporaries (all
448 /// locals that are neither arguments nor the return place).
450 pub fn vars_and_temps_iter(
452 ) -> impl DoubleEndedIterator<Item = Local> + ExactSizeIterator {
453 (self.arg_count + 1..self.local_decls.len()).map(Local::new)
457 pub fn drain_vars_and_temps<'a>(&'a mut self) -> impl Iterator<Item = LocalDecl<'tcx>> + 'a {
458 self.local_decls.drain(self.arg_count + 1..)
461 /// Returns the source info associated with `location`.
462 pub fn source_info(&self, location: Location) -> &SourceInfo {
463 let block = &self[location.block];
464 let stmts = &block.statements;
465 let idx = location.statement_index;
466 if idx < stmts.len() {
467 &stmts[idx].source_info
469 assert_eq!(idx, stmts.len());
470 &block.terminator().source_info
474 /// Returns the return type; it always return first element from `local_decls` array.
476 pub fn return_ty(&self) -> Ty<'tcx> {
477 self.local_decls[RETURN_PLACE].ty
480 /// Returns the return type; it always return first element from `local_decls` array.
482 pub fn bound_return_ty(&self) -> ty::EarlyBinder<Ty<'tcx>> {
483 ty::EarlyBinder(self.local_decls[RETURN_PLACE].ty)
486 /// Gets the location of the terminator for the given block.
488 pub fn terminator_loc(&self, bb: BasicBlock) -> Location {
489 Location { block: bb, statement_index: self[bb].statements.len() }
492 pub fn stmt_at(&self, location: Location) -> Either<&Statement<'tcx>, &Terminator<'tcx>> {
493 let Location { block, statement_index } = location;
494 let block_data = &self.basic_blocks[block];
497 .get(statement_index)
499 .unwrap_or_else(|| Either::Right(block_data.terminator()))
503 pub fn yield_ty(&self) -> Option<Ty<'tcx>> {
504 self.generator.as_ref().and_then(|generator| generator.yield_ty)
508 pub fn generator_layout(&self) -> Option<&GeneratorLayout<'tcx>> {
509 self.generator.as_ref().and_then(|generator| generator.generator_layout.as_ref())
513 pub fn generator_drop(&self) -> Option<&Body<'tcx>> {
514 self.generator.as_ref().and_then(|generator| generator.generator_drop.as_ref())
518 pub fn generator_kind(&self) -> Option<GeneratorKind> {
519 self.generator.as_ref().map(|generator| generator.generator_kind)
523 pub fn should_skip(&self) -> bool {
524 let Some(injection_phase) = self.injection_phase else {
527 injection_phase > self.phase
531 pub fn is_custom_mir(&self) -> bool {
532 self.injection_phase.is_some()
536 #[derive(Copy, Clone, PartialEq, Eq, Debug, TyEncodable, TyDecodable, HashStable)]
539 /// Unsafe because of compiler-generated unsafe code, like `await` desugaring
541 /// Unsafe because of an unsafe fn
543 /// Unsafe because of an `unsafe` block
544 ExplicitUnsafe(hir::HirId),
547 impl<'tcx> Index<BasicBlock> for Body<'tcx> {
548 type Output = BasicBlockData<'tcx>;
551 fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
552 &self.basic_blocks[index]
556 impl<'tcx> IndexMut<BasicBlock> for Body<'tcx> {
558 fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> {
559 &mut self.basic_blocks.as_mut()[index]
563 #[derive(Copy, Clone, Debug, HashStable, TypeFoldable, TypeVisitable)]
564 pub enum ClearCrossCrate<T> {
569 impl<T> ClearCrossCrate<T> {
570 pub fn as_ref(&self) -> ClearCrossCrate<&T> {
572 ClearCrossCrate::Clear => ClearCrossCrate::Clear,
573 ClearCrossCrate::Set(v) => ClearCrossCrate::Set(v),
577 pub fn assert_crate_local(self) -> T {
579 ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"),
580 ClearCrossCrate::Set(v) => v,
585 const TAG_CLEAR_CROSS_CRATE_CLEAR: u8 = 0;
586 const TAG_CLEAR_CROSS_CRATE_SET: u8 = 1;
588 impl<E: TyEncoder, T: Encodable<E>> Encodable<E> for ClearCrossCrate<T> {
590 fn encode(&self, e: &mut E) {
591 if E::CLEAR_CROSS_CRATE {
596 ClearCrossCrate::Clear => TAG_CLEAR_CROSS_CRATE_CLEAR.encode(e),
597 ClearCrossCrate::Set(ref val) => {
598 TAG_CLEAR_CROSS_CRATE_SET.encode(e);
604 impl<D: TyDecoder, T: Decodable<D>> Decodable<D> for ClearCrossCrate<T> {
606 fn decode(d: &mut D) -> ClearCrossCrate<T> {
607 if D::CLEAR_CROSS_CRATE {
608 return ClearCrossCrate::Clear;
611 let discr = u8::decode(d);
614 TAG_CLEAR_CROSS_CRATE_CLEAR => ClearCrossCrate::Clear,
615 TAG_CLEAR_CROSS_CRATE_SET => {
616 let val = T::decode(d);
617 ClearCrossCrate::Set(val)
619 tag => panic!("Invalid tag for ClearCrossCrate: {:?}", tag),
624 /// Grouped information about the source code origin of a MIR entity.
625 /// Intended to be inspected by diagnostics and debuginfo.
626 /// Most passes can work with it as a whole, within a single function.
627 // The unofficial Cranelift backend, at least as of #65828, needs `SourceInfo` to implement `Eq` and
628 // `Hash`. Please ping @bjorn3 if removing them.
629 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)]
630 pub struct SourceInfo {
631 /// The source span for the AST pertaining to this MIR entity.
634 /// The source scope, keeping track of which bindings can be
635 /// seen by debuginfo, active lint levels, `unsafe {...}`, etc.
636 pub scope: SourceScope,
641 pub fn outermost(span: Span) -> Self {
642 SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE }
646 ///////////////////////////////////////////////////////////////////////////
647 // Variables and temps
649 rustc_index::newtype_index! {
650 #[derive(HashStable)]
651 #[debug_format = "_{}"]
653 const RETURN_PLACE = 0;
657 impl Atom for Local {
658 fn index(self) -> usize {
663 /// Classifies locals into categories. See `Body::local_kind`.
664 #[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable)]
666 /// User-declared variable binding.
668 /// Compiler-introduced temporary.
670 /// Function argument.
672 /// Location of function's return value.
676 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
677 pub struct VarBindingForm<'tcx> {
678 /// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`?
679 pub binding_mode: ty::BindingMode,
680 /// If an explicit type was provided for this variable binding,
681 /// this holds the source Span of that type.
683 /// NOTE: if you want to change this to a `HirId`, be wary that
684 /// doing so breaks incremental compilation (as of this writing),
685 /// while a `Span` does not cause our tests to fail.
686 pub opt_ty_info: Option<Span>,
687 /// Place of the RHS of the =, or the subject of the `match` where this
688 /// variable is initialized. None in the case of `let PATTERN;`.
689 /// Some((None, ..)) in the case of and `let [mut] x = ...` because
690 /// (a) the right-hand side isn't evaluated as a place expression.
691 /// (b) it gives a way to separate this case from the remaining cases
693 pub opt_match_place: Option<(Option<Place<'tcx>>, Span)>,
694 /// The span of the pattern in which this variable was bound.
698 #[derive(Clone, Debug, TyEncodable, TyDecodable)]
699 pub enum BindingForm<'tcx> {
700 /// This is a binding for a non-`self` binding, or a `self` that has an explicit type.
701 Var(VarBindingForm<'tcx>),
702 /// Binding for a `self`/`&self`/`&mut self` binding where the type is implicit.
703 ImplicitSelf(ImplicitSelfKind),
704 /// Reference used in a guard expression to ensure immutability.
708 TrivialTypeTraversalAndLiftImpls! { BindingForm<'tcx>, }
710 mod binding_form_impl {
711 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
712 use rustc_query_system::ich::StableHashingContext;
714 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
715 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
716 use super::BindingForm::*;
717 std::mem::discriminant(self).hash_stable(hcx, hasher);
720 Var(binding) => binding.hash_stable(hcx, hasher),
721 ImplicitSelf(kind) => kind.hash_stable(hcx, hasher),
728 /// `BlockTailInfo` is attached to the `LocalDecl` for temporaries
729 /// created during evaluation of expressions in a block tail
730 /// expression; that is, a block like `{ STMT_1; STMT_2; EXPR }`.
732 /// It is used to improve diagnostics when such temporaries are
733 /// involved in borrow_check errors, e.g., explanations of where the
734 /// temporaries come from, when their destructors are run, and/or how
735 /// one might revise the code to satisfy the borrow checker's rules.
736 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
737 pub struct BlockTailInfo {
738 /// If `true`, then the value resulting from evaluating this tail
739 /// expression is ignored by the block's expression context.
741 /// Examples include `{ ...; tail };` and `let _ = { ...; tail };`
742 /// but not e.g., `let _x = { ...; tail };`
743 pub tail_result_is_ignored: bool,
745 /// `Span` of the tail expression.
751 /// This can be a binding declared by the user, a temporary inserted by the compiler, a function
752 /// argument, or the return place.
753 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
754 pub struct LocalDecl<'tcx> {
755 /// Whether this is a mutable binding (i.e., `let x` or `let mut x`).
757 /// Temporaries and the return place are always mutable.
758 pub mutability: Mutability,
760 // FIXME(matthewjasper) Don't store in this in `Body`
761 pub local_info: Option<Box<LocalInfo<'tcx>>>,
763 /// `true` if this is an internal local.
765 /// These locals are not based on types in the source code and are only used
766 /// for a few desugarings at the moment.
768 /// The generator transformation will sanity check the locals which are live
769 /// across a suspension point against the type components of the generator
770 /// which type checking knows are live across a suspension point. We need to
771 /// flag drop flags to avoid triggering this check as they are introduced
772 /// outside of type inference.
774 /// This should be sound because the drop flags are fully algebraic, and
775 /// therefore don't affect the auto-trait or outlives properties of the
779 /// If this local is a temporary and `is_block_tail` is `Some`,
780 /// then it is a temporary created for evaluation of some
781 /// subexpression of some block's tail expression (with no
782 /// intervening statement context).
783 // FIXME(matthewjasper) Don't store in this in `Body`
784 pub is_block_tail: Option<BlockTailInfo>,
786 /// The type of this local.
789 /// If the user manually ascribed a type to this variable,
790 /// e.g., via `let x: T`, then we carry that type here. The MIR
791 /// borrow checker needs this information since it can affect
792 /// region inference.
793 // FIXME(matthewjasper) Don't store in this in `Body`
794 pub user_ty: Option<Box<UserTypeProjections>>,
796 /// The *syntactic* (i.e., not visibility) source scope the local is defined
797 /// in. If the local was defined in a let-statement, this
798 /// is *within* the let-statement, rather than outside
801 /// This is needed because the visibility source scope of locals within
802 /// a let-statement is weird.
804 /// The reason is that we want the local to be *within* the let-statement
805 /// for lint purposes, but we want the local to be *after* the let-statement
806 /// for names-in-scope purposes.
808 /// That's it, if we have a let-statement like the one in this
812 /// fn foo(x: &str) {
813 /// #[allow(unused_mut)]
814 /// let mut x: u32 = { // <- one unused mut
815 /// let mut y: u32 = x.parse().unwrap();
822 /// Then, from a lint point of view, the declaration of `x: u32`
823 /// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the
824 /// lint scopes are the same as the AST/HIR nesting.
826 /// However, from a name lookup point of view, the scopes look more like
827 /// as if the let-statements were `match` expressions:
830 /// fn foo(x: &str) {
832 /// match x.parse::<u32>().unwrap() {
841 /// We care about the name-lookup scopes for debuginfo - if the
842 /// debuginfo instruction pointer is at the call to `x.parse()`, we
843 /// want `x` to refer to `x: &str`, but if it is at the call to
844 /// `drop(x)`, we want it to refer to `x: u32`.
846 /// To allow both uses to work, we need to have more than a single scope
847 /// for a local. We have the `source_info.scope` represent the "syntactic"
848 /// lint scope (with a variable being under its let block) while the
849 /// `var_debug_info.source_info.scope` represents the "local variable"
850 /// scope (where the "rest" of a block is under all prior let-statements).
852 /// The end result looks like this:
856 /// │{ argument x: &str }
858 /// │ │{ #[allow(unused_mut)] } // This is actually split into 2 scopes
859 /// │ │ // in practice because I'm lazy.
861 /// │ │← x.source_info.scope
862 /// │ │← `x.parse().unwrap()`
864 /// │ │ │← y.source_info.scope
866 /// │ │ │{ let y: u32 }
868 /// │ │ │← y.var_debug_info.source_info.scope
871 /// │ │{ let x: u32 }
872 /// │ │← x.var_debug_info.source_info.scope
873 /// │ │← `drop(x)` // This accesses `x: u32`.
875 pub source_info: SourceInfo,
878 /// Extra information about a some locals that's used for diagnostics and for
879 /// classifying variables into local variables, statics, etc, which is needed e.g.
880 /// for unsafety checking.
882 /// Not used for non-StaticRef temporaries, the return place, or anonymous
883 /// function parameters.
884 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
885 pub enum LocalInfo<'tcx> {
886 /// A user-defined local variable or function parameter
888 /// The `BindingForm` is solely used for local diagnostics when generating
889 /// warnings/errors when compiling the current crate, and therefore it need
890 /// not be visible across crates.
891 User(ClearCrossCrate<BindingForm<'tcx>>),
892 /// A temporary created that references the static with the given `DefId`.
893 StaticRef { def_id: DefId, is_thread_local: bool },
894 /// A temporary created that references the const with the given `DefId`
895 ConstRef { def_id: DefId },
896 /// A temporary created during the creation of an aggregate
897 /// (e.g. a temporary for `foo` in `MyStruct { my_field: foo }`)
899 /// A temporary created during the pass `Derefer` to avoid it's retagging
901 /// A temporary created for borrow checking.
905 impl<'tcx> LocalDecl<'tcx> {
906 /// Returns `true` only if local is a binding that can itself be
907 /// made mutable via the addition of the `mut` keyword, namely
908 /// something like the occurrences of `x` in:
909 /// - `fn foo(x: Type) { ... }`,
911 /// - or `match ... { C(x) => ... }`
912 pub fn can_be_made_mutable(&self) -> bool {
915 Some(box LocalInfo::User(ClearCrossCrate::Set(
916 BindingForm::Var(VarBindingForm {
917 binding_mode: ty::BindingMode::BindByValue(_),
921 }) | BindingForm::ImplicitSelf(ImplicitSelfKind::Imm),
926 /// Returns `true` if local is definitely not a `ref ident` or
927 /// `ref mut ident` binding. (Such bindings cannot be made into
928 /// mutable bindings, but the inverse does not necessarily hold).
929 pub fn is_nonref_binding(&self) -> bool {
932 Some(box LocalInfo::User(ClearCrossCrate::Set(
933 BindingForm::Var(VarBindingForm {
934 binding_mode: ty::BindingMode::BindByValue(_),
938 }) | BindingForm::ImplicitSelf(_),
943 /// Returns `true` if this variable is a named variable or function
944 /// parameter declared by the user.
946 pub fn is_user_variable(&self) -> bool {
947 matches!(self.local_info, Some(box LocalInfo::User(_)))
950 /// Returns `true` if this is a reference to a variable bound in a `match`
951 /// expression that is used to access said variable for the guard of the
953 pub fn is_ref_for_guard(&self) -> bool {
956 Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::RefForGuard)))
960 /// Returns `Some` if this is a reference to a static item that is used to
961 /// access that static.
962 pub fn is_ref_to_static(&self) -> bool {
963 matches!(self.local_info, Some(box LocalInfo::StaticRef { .. }))
966 /// Returns `Some` if this is a reference to a thread-local static item that is used to
967 /// access that static.
968 pub fn is_ref_to_thread_local(&self) -> bool {
969 match self.local_info {
970 Some(box LocalInfo::StaticRef { is_thread_local, .. }) => is_thread_local,
975 /// Returns `true` if this is a DerefTemp
976 pub fn is_deref_temp(&self) -> bool {
977 match self.local_info {
978 Some(box LocalInfo::DerefTemp) => return true,
984 /// Returns `true` is the local is from a compiler desugaring, e.g.,
985 /// `__next` from a `for` loop.
987 pub fn from_compiler_desugaring(&self) -> bool {
988 self.source_info.span.desugaring_kind().is_some()
991 /// Creates a new `LocalDecl` for a temporary: mutable, non-internal.
993 pub fn new(ty: Ty<'tcx>, span: Span) -> Self {
994 Self::with_source_info(ty, SourceInfo::outermost(span))
997 /// Like `LocalDecl::new`, but takes a `SourceInfo` instead of a `Span`.
999 pub fn with_source_info(ty: Ty<'tcx>, source_info: SourceInfo) -> Self {
1001 mutability: Mutability::Mut,
1004 is_block_tail: None,
1011 /// Converts `self` into same `LocalDecl` except tagged as internal.
1013 pub fn internal(mut self) -> Self {
1014 self.internal = true;
1018 /// Converts `self` into same `LocalDecl` except tagged as immutable.
1020 pub fn immutable(mut self) -> Self {
1021 self.mutability = Mutability::Not;
1025 /// Converts `self` into same `LocalDecl` except tagged as internal temporary.
1027 pub fn block_tail(mut self, info: BlockTailInfo) -> Self {
1028 assert!(self.is_block_tail.is_none());
1029 self.is_block_tail = Some(info);
1034 #[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1035 pub enum VarDebugInfoContents<'tcx> {
1036 /// NOTE(eddyb) There's an unenforced invariant that this `Place` is
1037 /// based on a `Local`, not a `Static`, and contains no indexing.
1039 Const(Constant<'tcx>),
1040 /// The user variable's data is split across several fragments,
1041 /// each described by a `VarDebugInfoFragment`.
1042 /// See DWARF 5's "2.6.1.2 Composite Location Descriptions"
1043 /// and LLVM's `DW_OP_LLVM_fragment` for more details on
1044 /// the underlying debuginfo feature this relies on.
1046 /// Type of the original user variable.
1048 /// All the parts of the original user variable, which ended
1049 /// up in disjoint places, due to optimizations.
1050 fragments: Vec<VarDebugInfoFragment<'tcx>>,
1054 impl<'tcx> Debug for VarDebugInfoContents<'tcx> {
1055 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1057 VarDebugInfoContents::Const(c) => write!(fmt, "{}", c),
1058 VarDebugInfoContents::Place(p) => write!(fmt, "{:?}", p),
1059 VarDebugInfoContents::Composite { ty, fragments } => {
1060 write!(fmt, "{:?}{{ ", ty)?;
1061 for f in fragments.iter() {
1062 write!(fmt, "{:?}, ", f)?;
1070 #[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1071 pub struct VarDebugInfoFragment<'tcx> {
1072 /// Where in the composite user variable this fragment is,
1073 /// represented as a "projection" into the composite variable.
1074 /// At lower levels, this corresponds to a byte/bit range.
1075 // NOTE(eddyb) there's an unenforced invariant that this contains
1076 // only `Field`s, and not into `enum` variants or `union`s.
1077 // FIXME(eddyb) support this for `enum`s by either using DWARF's
1078 // more advanced control-flow features (unsupported by LLVM?)
1079 // to match on the discriminant, or by using custom type debuginfo
1080 // with non-overlapping variants for the composite variable.
1081 pub projection: Vec<PlaceElem<'tcx>>,
1083 /// Where the data for this fragment can be found.
1084 // NOTE(eddyb) There's an unenforced invariant that this `Place` is
1085 // contains no indexing (with a non-constant index).
1086 pub contents: Place<'tcx>,
1089 impl Debug for VarDebugInfoFragment<'_> {
1090 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1091 for elem in self.projection.iter() {
1093 ProjectionElem::Field(field, _) => {
1094 write!(fmt, ".{:?}", field.index())?;
1096 _ => bug!("unsupported fragment projection `{:?}`", elem),
1100 write!(fmt, " => {:?}", self.contents)
1104 /// Debug information pertaining to a user variable.
1105 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1106 pub struct VarDebugInfo<'tcx> {
1109 /// Source info of the user variable, including the scope
1110 /// within which the variable is visible (to debuginfo)
1111 /// (see `LocalDecl`'s `source_info` field for more details).
1112 pub source_info: SourceInfo,
1114 /// Where the data for this user variable is to be found.
1115 pub value: VarDebugInfoContents<'tcx>,
1118 ///////////////////////////////////////////////////////////////////////////
1121 rustc_index::newtype_index! {
1122 /// A node in the MIR [control-flow graph][CFG].
1124 /// There are no branches (e.g., `if`s, function calls, etc.) within a basic block, which makes
1125 /// it easier to do [data-flow analyses] and optimizations. Instead, branches are represented
1126 /// as an edge in a graph between basic blocks.
1128 /// Basic blocks consist of a series of [statements][Statement], ending with a
1129 /// [terminator][Terminator]. Basic blocks can have multiple predecessors and successors,
1130 /// however there is a MIR pass ([`CriticalCallEdges`]) that removes *critical edges*, which
1131 /// are edges that go from a multi-successor node to a multi-predecessor node. This pass is
1132 /// needed because some analyses require that there are no critical edges in the CFG.
1134 /// Note that this type is just an index into [`Body.basic_blocks`](Body::basic_blocks);
1135 /// the actual data that a basic block holds is in [`BasicBlockData`].
1137 /// Read more about basic blocks in the [rustc-dev-guide][guide-mir].
1139 /// [CFG]: https://rustc-dev-guide.rust-lang.org/appendix/background.html#cfg
1140 /// [data-flow analyses]:
1141 /// https://rustc-dev-guide.rust-lang.org/appendix/background.html#what-is-a-dataflow-analysis
1142 /// [`CriticalCallEdges`]: ../../rustc_const_eval/transform/add_call_guards/enum.AddCallGuards.html#variant.CriticalCallEdges
1143 /// [guide-mir]: https://rustc-dev-guide.rust-lang.org/mir/
1144 #[derive(HashStable)]
1145 #[debug_format = "bb{}"]
1146 pub struct BasicBlock {
1147 const START_BLOCK = 0;
1152 pub fn start_location(self) -> Location {
1153 Location { block: self, statement_index: 0 }
1157 ///////////////////////////////////////////////////////////////////////////
1160 /// Data for a basic block, including a list of its statements.
1162 /// See [`BasicBlock`] for documentation on what basic blocks are at a high level.
1163 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1164 pub struct BasicBlockData<'tcx> {
1165 /// List of statements in this block.
1166 pub statements: Vec<Statement<'tcx>>,
1168 /// Terminator for this block.
1170 /// N.B., this should generally ONLY be `None` during construction.
1171 /// Therefore, you should generally access it via the
1172 /// `terminator()` or `terminator_mut()` methods. The only
1173 /// exception is that certain passes, such as `simplify_cfg`, swap
1174 /// out the terminator temporarily with `None` while they continue
1175 /// to recurse over the set of basic blocks.
1176 pub terminator: Option<Terminator<'tcx>>,
1178 /// If true, this block lies on an unwind path. This is used
1179 /// during codegen where distinct kinds of basic blocks may be
1180 /// generated (particularly for MSVC cleanup). Unwind blocks must
1181 /// only branch to other unwind blocks.
1182 pub is_cleanup: bool,
1185 impl<'tcx> BasicBlockData<'tcx> {
1186 pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
1187 BasicBlockData { statements: vec![], terminator, is_cleanup: false }
1190 /// Accessor for terminator.
1192 /// Terminator may not be None after construction of the basic block is complete. This accessor
1193 /// provides a convenient way to reach the terminator.
1195 pub fn terminator(&self) -> &Terminator<'tcx> {
1196 self.terminator.as_ref().expect("invalid terminator state")
1200 pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
1201 self.terminator.as_mut().expect("invalid terminator state")
1204 pub fn retain_statements<F>(&mut self, mut f: F)
1206 F: FnMut(&mut Statement<'_>) -> bool,
1208 for s in &mut self.statements {
1215 pub fn expand_statements<F, I>(&mut self, mut f: F)
1217 F: FnMut(&mut Statement<'tcx>) -> Option<I>,
1218 I: iter::TrustedLen<Item = Statement<'tcx>>,
1220 // Gather all the iterators we'll need to splice in, and their positions.
1221 let mut splices: Vec<(usize, I)> = vec![];
1222 let mut extra_stmts = 0;
1223 for (i, s) in self.statements.iter_mut().enumerate() {
1224 if let Some(mut new_stmts) = f(s) {
1225 if let Some(first) = new_stmts.next() {
1226 // We can already store the first new statement.
1229 // Save the other statements for optimized splicing.
1230 let remaining = new_stmts.size_hint().0;
1232 splices.push((i + 1 + extra_stmts, new_stmts));
1233 extra_stmts += remaining;
1241 // Splice in the new statements, from the end of the block.
1242 // FIXME(eddyb) This could be more efficient with a "gap buffer"
1243 // where a range of elements ("gap") is left uninitialized, with
1244 // splicing adding new elements to the end of that gap and moving
1245 // existing elements from before the gap to the end of the gap.
1246 // For now, this is safe code, emulating a gap but initializing it.
1247 let mut gap = self.statements.len()..self.statements.len() + extra_stmts;
1248 self.statements.resize(
1250 Statement { source_info: SourceInfo::outermost(DUMMY_SP), kind: StatementKind::Nop },
1252 for (splice_start, new_stmts) in splices.into_iter().rev() {
1253 let splice_end = splice_start + new_stmts.size_hint().0;
1254 while gap.end > splice_end {
1257 self.statements.swap(gap.start, gap.end);
1259 self.statements.splice(splice_start..splice_end, new_stmts);
1260 gap.end = splice_start;
1264 pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
1265 if index < self.statements.len() { &self.statements[index] } else { &self.terminator }
1268 /// Does the block have no statements and an unreachable terminator?
1269 pub fn is_empty_unreachable(&self) -> bool {
1270 self.statements.is_empty() && matches!(self.terminator().kind, TerminatorKind::Unreachable)
1274 impl<O> AssertKind<O> {
1275 /// Getting a description does not require `O` to be printable, and does not
1276 /// require allocation.
1277 /// The caller is expected to handle `BoundsCheck` separately.
1278 pub fn description(&self) -> &'static str {
1281 Overflow(BinOp::Add, _, _) => "attempt to add with overflow",
1282 Overflow(BinOp::Sub, _, _) => "attempt to subtract with overflow",
1283 Overflow(BinOp::Mul, _, _) => "attempt to multiply with overflow",
1284 Overflow(BinOp::Div, _, _) => "attempt to divide with overflow",
1285 Overflow(BinOp::Rem, _, _) => "attempt to calculate the remainder with overflow",
1286 OverflowNeg(_) => "attempt to negate with overflow",
1287 Overflow(BinOp::Shr, _, _) => "attempt to shift right with overflow",
1288 Overflow(BinOp::Shl, _, _) => "attempt to shift left with overflow",
1289 Overflow(op, _, _) => bug!("{:?} cannot overflow", op),
1290 DivisionByZero(_) => "attempt to divide by zero",
1291 RemainderByZero(_) => "attempt to calculate the remainder with a divisor of zero",
1292 ResumedAfterReturn(GeneratorKind::Gen) => "generator resumed after completion",
1293 ResumedAfterReturn(GeneratorKind::Async(_)) => "`async fn` resumed after completion",
1294 ResumedAfterPanic(GeneratorKind::Gen) => "generator resumed after panicking",
1295 ResumedAfterPanic(GeneratorKind::Async(_)) => "`async fn` resumed after panicking",
1296 BoundsCheck { .. } => bug!("Unexpected AssertKind"),
1300 /// Format the message arguments for the `assert(cond, msg..)` terminator in MIR printing.
1301 pub fn fmt_assert_args<W: Write>(&self, f: &mut W) -> fmt::Result
1307 BoundsCheck { ref len, ref index } => write!(
1309 "\"index out of bounds: the length is {{}} but the index is {{}}\", {:?}, {:?}",
1313 OverflowNeg(op) => {
1314 write!(f, "\"attempt to negate `{{}}`, which would overflow\", {:?}", op)
1316 DivisionByZero(op) => write!(f, "\"attempt to divide `{{}}` by zero\", {:?}", op),
1317 RemainderByZero(op) => write!(
1319 "\"attempt to calculate the remainder of `{{}}` with a divisor of zero\", {:?}",
1322 Overflow(BinOp::Add, l, r) => write!(
1324 "\"attempt to compute `{{}} + {{}}`, which would overflow\", {:?}, {:?}",
1327 Overflow(BinOp::Sub, l, r) => write!(
1329 "\"attempt to compute `{{}} - {{}}`, which would overflow\", {:?}, {:?}",
1332 Overflow(BinOp::Mul, l, r) => write!(
1334 "\"attempt to compute `{{}} * {{}}`, which would overflow\", {:?}, {:?}",
1337 Overflow(BinOp::Div, l, r) => write!(
1339 "\"attempt to compute `{{}} / {{}}`, which would overflow\", {:?}, {:?}",
1342 Overflow(BinOp::Rem, l, r) => write!(
1344 "\"attempt to compute the remainder of `{{}} % {{}}`, which would overflow\", {:?}, {:?}",
1347 Overflow(BinOp::Shr, _, r) => {
1348 write!(f, "\"attempt to shift right by `{{}}`, which would overflow\", {:?}", r)
1350 Overflow(BinOp::Shl, _, r) => {
1351 write!(f, "\"attempt to shift left by `{{}}`, which would overflow\", {:?}", r)
1353 _ => write!(f, "\"{}\"", self.description()),
1358 impl<O: fmt::Debug> fmt::Debug for AssertKind<O> {
1359 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1362 BoundsCheck { ref len, ref index } => write!(
1364 "index out of bounds: the length is {:?} but the index is {:?}",
1367 OverflowNeg(op) => write!(f, "attempt to negate `{:#?}`, which would overflow", op),
1368 DivisionByZero(op) => write!(f, "attempt to divide `{:#?}` by zero", op),
1369 RemainderByZero(op) => write!(
1371 "attempt to calculate the remainder of `{:#?}` with a divisor of zero",
1374 Overflow(BinOp::Add, l, r) => {
1375 write!(f, "attempt to compute `{:#?} + {:#?}`, which would overflow", l, r)
1377 Overflow(BinOp::Sub, l, r) => {
1378 write!(f, "attempt to compute `{:#?} - {:#?}`, which would overflow", l, r)
1380 Overflow(BinOp::Mul, l, r) => {
1381 write!(f, "attempt to compute `{:#?} * {:#?}`, which would overflow", l, r)
1383 Overflow(BinOp::Div, l, r) => {
1384 write!(f, "attempt to compute `{:#?} / {:#?}`, which would overflow", l, r)
1386 Overflow(BinOp::Rem, l, r) => write!(
1388 "attempt to compute the remainder of `{:#?} % {:#?}`, which would overflow",
1391 Overflow(BinOp::Shr, _, r) => {
1392 write!(f, "attempt to shift right by `{:#?}`, which would overflow", r)
1394 Overflow(BinOp::Shl, _, r) => {
1395 write!(f, "attempt to shift left by `{:#?}`, which would overflow", r)
1397 _ => write!(f, "{}", self.description()),
1402 ///////////////////////////////////////////////////////////////////////////
1405 /// A statement in a basic block, including information about its source code.
1406 #[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1407 pub struct Statement<'tcx> {
1408 pub source_info: SourceInfo,
1409 pub kind: StatementKind<'tcx>,
1412 impl Statement<'_> {
1413 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
1414 /// invalidating statement indices in `Location`s.
1415 pub fn make_nop(&mut self) {
1416 self.kind = StatementKind::Nop
1419 /// Changes a statement to a nop and returns the original statement.
1420 #[must_use = "If you don't need the statement, use `make_nop` instead"]
1421 pub fn replace_nop(&mut self) -> Self {
1423 source_info: self.source_info,
1424 kind: mem::replace(&mut self.kind, StatementKind::Nop),
1429 impl Debug for Statement<'_> {
1430 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1431 use self::StatementKind::*;
1433 Assign(box (ref place, ref rv)) => write!(fmt, "{:?} = {:?}", place, rv),
1434 FakeRead(box (ref cause, ref place)) => {
1435 write!(fmt, "FakeRead({:?}, {:?})", cause, place)
1437 Retag(ref kind, ref place) => write!(
1441 RetagKind::FnEntry => "[fn entry] ",
1442 RetagKind::TwoPhase => "[2phase] ",
1443 RetagKind::Raw => "[raw] ",
1444 RetagKind::Default => "",
1448 StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place),
1449 StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place),
1450 SetDiscriminant { ref place, variant_index } => {
1451 write!(fmt, "discriminant({:?}) = {:?}", place, variant_index)
1453 Deinit(ref place) => write!(fmt, "Deinit({:?})", place),
1454 AscribeUserType(box (ref place, ref c_ty), ref variance) => {
1455 write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty)
1457 Coverage(box self::Coverage { ref kind, code_region: Some(ref rgn) }) => {
1458 write!(fmt, "Coverage::{:?} for {:?}", kind, rgn)
1460 Coverage(box ref coverage) => write!(fmt, "Coverage::{:?}", coverage.kind),
1461 Intrinsic(box ref intrinsic) => write!(fmt, "{intrinsic}"),
1462 ConstEvalCounter => write!(fmt, "ConstEvalCounter"),
1463 Nop => write!(fmt, "nop"),
1468 impl<'tcx> StatementKind<'tcx> {
1469 pub fn as_assign_mut(&mut self) -> Option<&mut (Place<'tcx>, Rvalue<'tcx>)> {
1471 StatementKind::Assign(x) => Some(x),
1476 pub fn as_assign(&self) -> Option<&(Place<'tcx>, Rvalue<'tcx>)> {
1478 StatementKind::Assign(x) => Some(x),
1484 ///////////////////////////////////////////////////////////////////////////
1487 impl<V, T> ProjectionElem<V, T> {
1488 /// Returns `true` if the target of this projection may refer to a different region of memory
1490 fn is_indirect(&self) -> bool {
1492 Self::Deref => true,
1496 | Self::OpaqueCast(_)
1497 | Self::ConstantIndex { .. }
1498 | Self::Subslice { .. }
1499 | Self::Downcast(_, _) => false,
1503 /// Returns `true` if this is a `Downcast` projection with the given `VariantIdx`.
1504 pub fn is_downcast_to(&self, v: VariantIdx) -> bool {
1505 matches!(*self, Self::Downcast(_, x) if x == v)
1508 /// Returns `true` if this is a `Field` projection with the given index.
1509 pub fn is_field_to(&self, f: Field) -> bool {
1510 matches!(*self, Self::Field(x, _) if x == f)
1514 /// Alias for projections as they appear in `UserTypeProjection`, where we
1515 /// need neither the `V` parameter for `Index` nor the `T` for `Field`.
1516 pub type ProjectionKind = ProjectionElem<(), ()>;
1518 rustc_index::newtype_index! {
1519 /// A [newtype'd][wrapper] index type in the MIR [control-flow graph][CFG]
1521 /// A field (e.g., `f` in `_1.f`) is one variant of [`ProjectionElem`]. Conceptually,
1522 /// rustc can identify that a field projection refers to either two different regions of memory
1523 /// or the same one between the base and the 'projection element'.
1524 /// Read more about projections in the [rustc-dev-guide][mir-datatypes]
1526 /// [wrapper]: https://rustc-dev-guide.rust-lang.org/appendix/glossary.html#newtype
1527 /// [CFG]: https://rustc-dev-guide.rust-lang.org/appendix/background.html#cfg
1528 /// [mir-datatypes]: https://rustc-dev-guide.rust-lang.org/mir/index.html#mir-data-types
1529 #[derive(HashStable)]
1530 #[debug_format = "field[{}]"]
1534 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
1535 pub struct PlaceRef<'tcx> {
1537 pub projection: &'tcx [PlaceElem<'tcx>],
1540 // Once we stop implementing `Ord` for `DefId`,
1541 // this impl will be unnecessary. Until then, we'll
1542 // leave this impl in place to prevent re-adding a
1543 // dependency on the `Ord` impl for `DefId`
1544 impl<'tcx> !PartialOrd for PlaceRef<'tcx> {}
1546 impl<'tcx> Place<'tcx> {
1547 // FIXME change this to a const fn by also making List::empty a const fn.
1548 pub fn return_place() -> Place<'tcx> {
1549 Place { local: RETURN_PLACE, projection: List::empty() }
1552 /// Returns `true` if this `Place` contains a `Deref` projection.
1554 /// If `Place::is_indirect` returns false, the caller knows that the `Place` refers to the
1555 /// same region of memory as its base.
1556 pub fn is_indirect(&self) -> bool {
1557 self.projection.iter().any(|elem| elem.is_indirect())
1560 /// If MirPhase >= Derefered and if projection contains Deref,
1561 /// It's guaranteed to be in the first place
1562 pub fn has_deref(&self) -> bool {
1563 // To make sure this is not accidentally used in wrong mir phase
1565 self.projection.is_empty() || !self.projection[1..].contains(&PlaceElem::Deref)
1567 self.projection.first() == Some(&PlaceElem::Deref)
1570 /// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
1571 /// a single deref of a local.
1573 pub fn local_or_deref_local(&self) -> Option<Local> {
1574 self.as_ref().local_or_deref_local()
1577 /// If this place represents a local variable like `_X` with no
1578 /// projections, return `Some(_X)`.
1580 pub fn as_local(&self) -> Option<Local> {
1581 self.as_ref().as_local()
1585 pub fn as_ref(&self) -> PlaceRef<'tcx> {
1586 PlaceRef { local: self.local, projection: &self.projection }
1589 /// Iterate over the projections in evaluation order, i.e., the first element is the base with
1590 /// its projection and then subsequently more projections are added.
1591 /// As a concrete example, given the place a.b.c, this would yield:
1595 /// Given a place without projections, the iterator is empty.
1597 pub fn iter_projections(
1599 ) -> impl Iterator<Item = (PlaceRef<'tcx>, PlaceElem<'tcx>)> + DoubleEndedIterator {
1600 self.as_ref().iter_projections()
1603 /// Generates a new place by appending `more_projections` to the existing ones
1604 /// and interning the result.
1605 pub fn project_deeper(self, more_projections: &[PlaceElem<'tcx>], tcx: TyCtxt<'tcx>) -> Self {
1606 if more_projections.is_empty() {
1610 let mut v: Vec<PlaceElem<'tcx>>;
1612 let new_projections = if self.projection.is_empty() {
1615 v = Vec::with_capacity(self.projection.len() + more_projections.len());
1616 v.extend(self.projection);
1617 v.extend(more_projections);
1621 Place { local: self.local, projection: tcx.intern_place_elems(new_projections) }
1625 impl From<Local> for Place<'_> {
1627 fn from(local: Local) -> Self {
1628 Place { local, projection: List::empty() }
1632 impl<'tcx> PlaceRef<'tcx> {
1633 /// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
1634 /// a single deref of a local.
1635 pub fn local_or_deref_local(&self) -> Option<Local> {
1637 PlaceRef { local, projection: [] }
1638 | PlaceRef { local, projection: [ProjectionElem::Deref] } => Some(local),
1643 /// If MirPhase >= Derefered and if projection contains Deref,
1644 /// It's guaranteed to be in the first place
1645 pub fn has_deref(&self) -> bool {
1646 self.projection.first() == Some(&PlaceElem::Deref)
1649 /// If this place represents a local variable like `_X` with no
1650 /// projections, return `Some(_X)`.
1652 pub fn as_local(&self) -> Option<Local> {
1654 PlaceRef { local, projection: [] } => Some(local),
1660 pub fn last_projection(&self) -> Option<(PlaceRef<'tcx>, PlaceElem<'tcx>)> {
1661 if let &[ref proj_base @ .., elem] = self.projection {
1662 Some((PlaceRef { local: self.local, projection: proj_base }, elem))
1668 /// Iterate over the projections in evaluation order, i.e., the first element is the base with
1669 /// its projection and then subsequently more projections are added.
1670 /// As a concrete example, given the place a.b.c, this would yield:
1674 /// Given a place without projections, the iterator is empty.
1676 pub fn iter_projections(
1678 ) -> impl Iterator<Item = (PlaceRef<'tcx>, PlaceElem<'tcx>)> + DoubleEndedIterator {
1679 self.projection.iter().enumerate().map(move |(i, proj)| {
1680 let base = PlaceRef { local: self.local, projection: &self.projection[..i] };
1686 impl Debug for Place<'_> {
1687 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1688 for elem in self.projection.iter().rev() {
1690 ProjectionElem::OpaqueCast(_)
1691 | ProjectionElem::Downcast(_, _)
1692 | ProjectionElem::Field(_, _) => {
1693 write!(fmt, "(").unwrap();
1695 ProjectionElem::Deref => {
1696 write!(fmt, "(*").unwrap();
1698 ProjectionElem::Index(_)
1699 | ProjectionElem::ConstantIndex { .. }
1700 | ProjectionElem::Subslice { .. } => {}
1704 write!(fmt, "{:?}", self.local)?;
1706 for elem in self.projection.iter() {
1708 ProjectionElem::OpaqueCast(ty) => {
1709 write!(fmt, " as {})", ty)?;
1711 ProjectionElem::Downcast(Some(name), _index) => {
1712 write!(fmt, " as {})", name)?;
1714 ProjectionElem::Downcast(None, index) => {
1715 write!(fmt, " as variant#{:?})", index)?;
1717 ProjectionElem::Deref => {
1720 ProjectionElem::Field(field, ty) => {
1721 write!(fmt, ".{:?}: {:?})", field.index(), ty)?;
1723 ProjectionElem::Index(ref index) => {
1724 write!(fmt, "[{:?}]", index)?;
1726 ProjectionElem::ConstantIndex { offset, min_length, from_end: false } => {
1727 write!(fmt, "[{:?} of {:?}]", offset, min_length)?;
1729 ProjectionElem::ConstantIndex { offset, min_length, from_end: true } => {
1730 write!(fmt, "[-{:?} of {:?}]", offset, min_length)?;
1732 ProjectionElem::Subslice { from, to, from_end: true } if to == 0 => {
1733 write!(fmt, "[{:?}:]", from)?;
1735 ProjectionElem::Subslice { from, to, from_end: true } if from == 0 => {
1736 write!(fmt, "[:-{:?}]", to)?;
1738 ProjectionElem::Subslice { from, to, from_end: true } => {
1739 write!(fmt, "[{:?}:-{:?}]", from, to)?;
1741 ProjectionElem::Subslice { from, to, from_end: false } => {
1742 write!(fmt, "[{:?}..{:?}]", from, to)?;
1751 ///////////////////////////////////////////////////////////////////////////
1754 rustc_index::newtype_index! {
1755 #[derive(HashStable)]
1756 #[debug_format = "scope[{}]"]
1757 pub struct SourceScope {
1758 const OUTERMOST_SOURCE_SCOPE = 0;
1763 /// Finds the original HirId this MIR item came from.
1764 /// This is necessary after MIR optimizations, as otherwise we get a HirId
1765 /// from the function that was inlined instead of the function call site.
1768 source_scopes: &IndexVec<SourceScope, SourceScopeData<'_>>,
1769 ) -> Option<HirId> {
1770 let mut data = &source_scopes[self];
1771 // FIXME(oli-obk): we should be able to just walk the `inlined_parent_scope`, but it
1772 // does not work as I thought it would. Needs more investigation and documentation.
1773 while data.inlined.is_some() {
1775 data = &source_scopes[data.parent_scope.unwrap()];
1778 match &data.local_data {
1779 ClearCrossCrate::Set(data) => Some(data.lint_root),
1780 ClearCrossCrate::Clear => None,
1784 /// The instance this source scope was inlined from, if any.
1786 pub fn inlined_instance<'tcx>(
1788 source_scopes: &IndexVec<SourceScope, SourceScopeData<'tcx>>,
1789 ) -> Option<ty::Instance<'tcx>> {
1790 let scope_data = &source_scopes[self];
1791 if let Some((inlined_instance, _)) = scope_data.inlined {
1792 Some(inlined_instance)
1793 } else if let Some(inlined_scope) = scope_data.inlined_parent_scope {
1794 Some(source_scopes[inlined_scope].inlined.unwrap().0)
1801 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1802 pub struct SourceScopeData<'tcx> {
1804 pub parent_scope: Option<SourceScope>,
1806 /// Whether this scope is the root of a scope tree of another body,
1807 /// inlined into this body by the MIR inliner.
1808 /// `ty::Instance` is the callee, and the `Span` is the call site.
1809 pub inlined: Option<(ty::Instance<'tcx>, Span)>,
1811 /// Nearest (transitive) parent scope (if any) which is inlined.
1812 /// This is an optimization over walking up `parent_scope`
1813 /// until a scope with `inlined: Some(...)` is found.
1814 pub inlined_parent_scope: Option<SourceScope>,
1816 /// Crate-local information for this source scope, that can't (and
1817 /// needn't) be tracked across crates.
1818 pub local_data: ClearCrossCrate<SourceScopeLocalData>,
1821 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
1822 pub struct SourceScopeLocalData {
1823 /// An `HirId` with lint levels equivalent to this scope's lint levels.
1824 pub lint_root: hir::HirId,
1825 /// The unsafe block that contains this node.
1829 ///////////////////////////////////////////////////////////////////////////
1832 impl<'tcx> Debug for Operand<'tcx> {
1833 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1834 use self::Operand::*;
1836 Constant(ref a) => write!(fmt, "{:?}", a),
1837 Copy(ref place) => write!(fmt, "{:?}", place),
1838 Move(ref place) => write!(fmt, "move {:?}", place),
1843 impl<'tcx> Operand<'tcx> {
1844 /// Convenience helper to make a constant that refers to the fn
1845 /// with given `DefId` and substs. Since this is used to synthesize
1846 /// MIR, assumes `user_ty` is None.
1847 pub fn function_handle(
1850 substs: impl IntoIterator<Item = GenericArg<'tcx>>,
1853 let ty = tcx.mk_fn_def(def_id, substs);
1854 Operand::Constant(Box::new(Constant {
1857 literal: ConstantKind::Val(ConstValue::ZeroSized, ty),
1861 pub fn is_move(&self) -> bool {
1862 matches!(self, Operand::Move(..))
1865 /// Convenience helper to make a literal-like constant from a given scalar value.
1866 /// Since this is used to synthesize MIR, assumes `user_ty` is None.
1867 pub fn const_from_scalar(
1872 ) -> Operand<'tcx> {
1874 let param_env_and_ty = ty::ParamEnv::empty().and(ty);
1876 .layout_of(param_env_and_ty)
1877 .unwrap_or_else(|e| panic!("could not compute layout for {:?}: {:?}", ty, e))
1879 let scalar_size = match val {
1880 Scalar::Int(int) => int.size(),
1881 _ => panic!("Invalid scalar type {:?}", val),
1883 scalar_size == type_size
1885 Operand::Constant(Box::new(Constant {
1888 literal: ConstantKind::Val(ConstValue::Scalar(val), ty),
1892 pub fn to_copy(&self) -> Self {
1894 Operand::Copy(_) | Operand::Constant(_) => self.clone(),
1895 Operand::Move(place) => Operand::Copy(place),
1899 /// Returns the `Place` that is the target of this `Operand`, or `None` if this `Operand` is a
1901 pub fn place(&self) -> Option<Place<'tcx>> {
1903 Operand::Copy(place) | Operand::Move(place) => Some(*place),
1904 Operand::Constant(_) => None,
1908 /// Returns the `Constant` that is the target of this `Operand`, or `None` if this `Operand` is a
1910 pub fn constant(&self) -> Option<&Constant<'tcx>> {
1912 Operand::Constant(x) => Some(&**x),
1913 Operand::Copy(_) | Operand::Move(_) => None,
1917 /// Gets the `ty::FnDef` from an operand if it's a constant function item.
1919 /// While this is unlikely in general, it's the normal case of what you'll
1920 /// find as the `func` in a [`TerminatorKind::Call`].
1921 pub fn const_fn_def(&self) -> Option<(DefId, SubstsRef<'tcx>)> {
1922 let const_ty = self.constant()?.literal.ty();
1923 if let ty::FnDef(def_id, substs) = *const_ty.kind() { Some((def_id, substs)) } else { None }
1927 ///////////////////////////////////////////////////////////////////////////
1930 impl<'tcx> Rvalue<'tcx> {
1931 /// Returns true if rvalue can be safely removed when the result is unused.
1933 pub fn is_safe_to_remove(&self) -> bool {
1935 // Pointer to int casts may be side-effects due to exposing the provenance.
1936 // While the model is undecided, we should be conservative. See
1937 // <https://www.ralfj.de/blog/2022/04/11/provenance-exposed.html>
1938 Rvalue::Cast(CastKind::PointerExposeAddress, _, _) => false,
1941 | Rvalue::CopyForDeref(_)
1942 | Rvalue::Repeat(_, _)
1943 | Rvalue::Ref(_, _, _)
1944 | Rvalue::ThreadLocalRef(_)
1945 | Rvalue::AddressOf(_, _)
1949 | CastKind::FloatToInt
1950 | CastKind::FloatToFloat
1951 | CastKind::IntToFloat
1952 | CastKind::FnPtrToPtr
1953 | CastKind::PtrToPtr
1954 | CastKind::Pointer(_)
1955 | CastKind::PointerFromExposedAddress
1956 | CastKind::DynStar,
1960 | Rvalue::BinaryOp(_, _)
1961 | Rvalue::CheckedBinaryOp(_, _)
1962 | Rvalue::NullaryOp(_, _)
1963 | Rvalue::UnaryOp(_, _)
1964 | Rvalue::Discriminant(_)
1965 | Rvalue::Aggregate(_, _)
1966 | Rvalue::ShallowInitBox(_, _) => true,
1972 pub fn allows_two_phase_borrow(&self) -> bool {
1974 BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => false,
1975 BorrowKind::Mut { allow_two_phase_borrow } => allow_two_phase_borrow,
1979 // FIXME: won't be used after diagnostic migration
1980 pub fn describe_mutability(&self) -> &str {
1982 BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => "immutable",
1983 BorrowKind::Mut { .. } => "mutable",
1989 pub fn is_checkable(self) -> bool {
1991 matches!(self, Add | Sub | Mul | Shl | Shr)
1995 impl<'tcx> Debug for Rvalue<'tcx> {
1996 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1997 use self::Rvalue::*;
2000 Use(ref place) => write!(fmt, "{:?}", place),
2001 Repeat(ref a, b) => {
2002 write!(fmt, "[{:?}; ", a)?;
2003 pretty_print_const(b, fmt, false)?;
2006 Len(ref a) => write!(fmt, "Len({:?})", a),
2007 Cast(ref kind, ref place, ref ty) => {
2008 write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind)
2010 BinaryOp(ref op, box (ref a, ref b)) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
2011 CheckedBinaryOp(ref op, box (ref a, ref b)) => {
2012 write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b)
2014 UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
2015 Discriminant(ref place) => write!(fmt, "discriminant({:?})", place),
2016 NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
2017 ThreadLocalRef(did) => ty::tls::with(|tcx| {
2018 let muta = tcx.static_mutability(did).unwrap().prefix_str();
2019 write!(fmt, "&/*tls*/ {}{}", muta, tcx.def_path_str(did))
2021 Ref(region, borrow_kind, ref place) => {
2022 let kind_str = match borrow_kind {
2023 BorrowKind::Shared => "",
2024 BorrowKind::Shallow => "shallow ",
2025 BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ",
2028 // When printing regions, add trailing space if necessary.
2029 let print_region = ty::tls::with(|tcx| {
2030 tcx.sess.verbose() || tcx.sess.opts.unstable_opts.identify_regions
2032 let region = if print_region {
2033 let mut region = region.to_string();
2034 if !region.is_empty() {
2039 // Do not even print 'static
2042 write!(fmt, "&{}{}{:?}", region, kind_str, place)
2045 CopyForDeref(ref place) => write!(fmt, "deref_copy {:#?}", place),
2047 AddressOf(mutability, ref place) => {
2048 let kind_str = match mutability {
2049 Mutability::Mut => "mut",
2050 Mutability::Not => "const",
2053 write!(fmt, "&raw {} {:?}", kind_str, place)
2056 Aggregate(ref kind, ref places) => {
2057 let fmt_tuple = |fmt: &mut Formatter<'_>, name: &str| {
2058 let mut tuple_fmt = fmt.debug_tuple(name);
2059 for place in places {
2060 tuple_fmt.field(place);
2066 AggregateKind::Array(_) => write!(fmt, "{:?}", places),
2068 AggregateKind::Tuple => {
2069 if places.is_empty() {
2076 AggregateKind::Adt(adt_did, variant, substs, _user_ty, _) => {
2077 ty::tls::with(|tcx| {
2078 let variant_def = &tcx.adt_def(adt_did).variant(variant);
2079 let substs = tcx.lift(substs).expect("could not lift for printing");
2080 let name = FmtPrinter::new(tcx, Namespace::ValueNS)
2081 .print_def_path(variant_def.def_id, substs)?
2084 match variant_def.ctor_kind() {
2085 Some(CtorKind::Const) => fmt.write_str(&name),
2086 Some(CtorKind::Fn) => fmt_tuple(fmt, &name),
2088 let mut struct_fmt = fmt.debug_struct(&name);
2089 for (field, place) in iter::zip(&variant_def.fields, places) {
2090 struct_fmt.field(field.name.as_str(), place);
2098 AggregateKind::Closure(def_id, substs) => ty::tls::with(|tcx| {
2099 let name = if tcx.sess.opts.unstable_opts.span_free_formats {
2100 let substs = tcx.lift(substs).unwrap();
2103 tcx.def_path_str_with_substs(def_id.to_def_id(), substs),
2106 let span = tcx.def_span(def_id);
2109 tcx.sess.source_map().span_to_diagnostic_string(span)
2112 let mut struct_fmt = fmt.debug_struct(&name);
2114 // FIXME(project-rfc-2229#48): This should be a list of capture names/places
2115 if let Some(upvars) = tcx.upvars_mentioned(def_id) {
2116 for (&var_id, place) in iter::zip(upvars.keys(), places) {
2117 let var_name = tcx.hir().name(var_id);
2118 struct_fmt.field(var_name.as_str(), place);
2125 AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
2126 let name = format!("[generator@{:?}]", tcx.def_span(def_id));
2127 let mut struct_fmt = fmt.debug_struct(&name);
2129 // FIXME(project-rfc-2229#48): This should be a list of capture names/places
2130 if let Some(upvars) = tcx.upvars_mentioned(def_id) {
2131 for (&var_id, place) in iter::zip(upvars.keys(), places) {
2132 let var_name = tcx.hir().name(var_id);
2133 struct_fmt.field(var_name.as_str(), place);
2142 ShallowInitBox(ref place, ref ty) => {
2143 write!(fmt, "ShallowInitBox({:?}, {:?})", place, ty)
2149 ///////////////////////////////////////////////////////////////////////////
2152 /// Two constants are equal if they are the same constant. Note that
2153 /// this does not necessarily mean that they are `==` in Rust. In
2154 /// particular, one must be wary of `NaN`!
2156 #[derive(Clone, Copy, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)]
2157 #[derive(TypeFoldable, TypeVisitable)]
2158 pub struct Constant<'tcx> {
2161 /// Optional user-given type: for something like
2162 /// `collect::<Vec<_>>`, this would be present and would
2163 /// indicate that `Vec<_>` was explicitly specified.
2165 /// Needed for NLL to impose user-given type constraints.
2166 pub user_ty: Option<UserTypeAnnotationIndex>,
2168 pub literal: ConstantKind<'tcx>,
2171 #[derive(Clone, Copy, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable, Debug)]
2172 #[derive(Lift, TypeFoldable, TypeVisitable)]
2173 pub enum ConstantKind<'tcx> {
2174 /// This constant came from the type system
2175 Ty(ty::Const<'tcx>),
2177 /// An unevaluated mir constant which is not part of the type system.
2178 Unevaluated(UnevaluatedConst<'tcx>, Ty<'tcx>),
2180 /// This constant cannot go back into the type system, as it represents
2181 /// something the type system cannot handle (e.g. pointers).
2182 Val(interpret::ConstValue<'tcx>, Ty<'tcx>),
2185 impl<'tcx> Constant<'tcx> {
2186 pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option<DefId> {
2187 match self.literal.try_to_scalar() {
2188 Some(Scalar::Ptr(ptr, _size)) => match tcx.global_alloc(ptr.provenance) {
2189 GlobalAlloc::Static(def_id) => {
2190 assert!(!tcx.is_thread_local_static(def_id));
2199 pub fn ty(&self) -> Ty<'tcx> {
2204 impl<'tcx> ConstantKind<'tcx> {
2206 pub fn ty(&self) -> Ty<'tcx> {
2208 ConstantKind::Ty(c) => c.ty(),
2209 ConstantKind::Val(_, ty) | ConstantKind::Unevaluated(_, ty) => *ty,
2214 pub fn try_to_value(self, tcx: TyCtxt<'tcx>) -> Option<interpret::ConstValue<'tcx>> {
2216 ConstantKind::Ty(c) => match c.kind() {
2217 ty::ConstKind::Value(valtree) => Some(tcx.valtree_to_const_val((c.ty(), valtree))),
2220 ConstantKind::Val(val, _) => Some(val),
2221 ConstantKind::Unevaluated(..) => None,
2226 pub fn try_to_scalar(self) -> Option<Scalar> {
2228 ConstantKind::Ty(c) => match c.kind() {
2229 ty::ConstKind::Value(valtree) => match valtree {
2230 ty::ValTree::Leaf(scalar_int) => Some(Scalar::Int(scalar_int)),
2231 ty::ValTree::Branch(_) => None,
2235 ConstantKind::Val(val, _) => val.try_to_scalar(),
2236 ConstantKind::Unevaluated(..) => None,
2241 pub fn try_to_scalar_int(self) -> Option<ScalarInt> {
2242 Some(self.try_to_scalar()?.assert_int())
2246 pub fn try_to_bits(self, size: Size) -> Option<u128> {
2247 self.try_to_scalar_int()?.to_bits(size).ok()
2251 pub fn try_to_bool(self) -> Option<bool> {
2252 self.try_to_scalar_int()?.try_into().ok()
2256 pub fn eval(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self {
2259 if let Some(val) = c.kind().try_eval_for_mir(tcx, param_env) {
2261 Ok(val) => Self::Val(val, c.ty()),
2262 Err(_) => Self::Ty(tcx.const_error(self.ty())),
2268 Self::Val(_, _) => self,
2269 Self::Unevaluated(uneval, ty) => {
2270 // FIXME: We might want to have a `try_eval`-like function on `Unevaluated`
2271 match tcx.const_eval_resolve(param_env, uneval, None) {
2272 Ok(val) => Self::Val(val, ty),
2273 Err(ErrorHandled::TooGeneric) => self,
2274 Err(ErrorHandled::Reported(guar)) => {
2275 Self::Ty(tcx.const_error_with_guaranteed(ty, guar))
2282 /// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type.
2284 pub fn eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 {
2285 self.try_eval_bits(tcx, param_env, ty)
2286 .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self))
2290 pub fn try_eval_bits(
2293 param_env: ty::ParamEnv<'tcx>,
2297 Self::Ty(ct) => ct.try_eval_bits(tcx, param_env, ty),
2298 Self::Val(val, t) => {
2301 tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size;
2302 val.try_to_bits(size)
2304 Self::Unevaluated(uneval, ty) => {
2305 match tcx.const_eval_resolve(param_env, *uneval, None) {
2308 .layout_of(param_env.with_reveal_all_normalized(tcx).and(*ty))
2311 val.try_to_bits(size)
2320 pub fn try_eval_bool(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Option<bool> {
2322 Self::Ty(ct) => ct.try_eval_bool(tcx, param_env),
2323 Self::Val(val, _) => val.try_to_bool(),
2324 Self::Unevaluated(uneval, _) => {
2325 match tcx.const_eval_resolve(param_env, *uneval, None) {
2326 Ok(val) => val.try_to_bool(),
2334 pub fn try_eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Option<u64> {
2336 Self::Ty(ct) => ct.try_eval_usize(tcx, param_env),
2337 Self::Val(val, _) => val.try_to_machine_usize(tcx),
2338 Self::Unevaluated(uneval, _) => {
2339 match tcx.const_eval_resolve(param_env, *uneval, None) {
2340 Ok(val) => val.try_to_machine_usize(tcx),
2348 pub fn from_value(val: ConstValue<'tcx>, ty: Ty<'tcx>) -> Self {
2355 param_env_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
2358 .layout_of(param_env_ty)
2359 .unwrap_or_else(|e| {
2360 bug!("could not compute layout for {:?}: {:?}", param_env_ty.value, e)
2363 let cv = ConstValue::Scalar(Scalar::from_uint(bits, size));
2365 Self::Val(cv, param_env_ty.value)
2369 pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> Self {
2370 let cv = ConstValue::from_bool(v);
2371 Self::Val(cv, tcx.types.bool)
2375 pub fn zero_sized(ty: Ty<'tcx>) -> Self {
2376 let cv = ConstValue::ZeroSized;
2380 pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self {
2381 let ty = tcx.types.usize;
2382 Self::from_bits(tcx, n as u128, ty::ParamEnv::empty().and(ty))
2386 pub fn from_scalar(_tcx: TyCtxt<'tcx>, s: Scalar, ty: Ty<'tcx>) -> Self {
2387 let val = ConstValue::Scalar(s);
2391 /// Literals are converted to `ConstantKindVal`, const generic parameters are eagerly
2392 /// converted to a constant, everything else becomes `Unevaluated`.
2393 pub fn from_anon_const(
2396 param_env: ty::ParamEnv<'tcx>,
2398 Self::from_opt_const_arg_anon_const(tcx, ty::WithOptConstParam::unknown(def_id), param_env)
2401 #[instrument(skip(tcx), level = "debug", ret)]
2402 pub fn from_inline_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
2403 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2404 let body_id = match tcx.hir().get(hir_id) {
2405 hir::Node::AnonConst(ac) => ac.body,
2407 tcx.def_span(def_id.to_def_id()),
2408 "from_inline_const can only process anonymous constants"
2411 let expr = &tcx.hir().body(body_id).value;
2412 let ty = tcx.typeck(def_id).node_type(hir_id);
2414 let lit_input = match expr.kind {
2415 hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
2416 hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => match expr.kind {
2417 hir::ExprKind::Lit(ref lit) => {
2418 Some(LitToConstInput { lit: &lit.node, ty, neg: true })
2424 if let Some(lit_input) = lit_input {
2425 // If an error occurred, ignore that it's a literal and leave reporting the error up to
2427 match tcx.at(expr.span).lit_to_mir_constant(lit_input) {
2433 let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id());
2435 tcx.erase_regions(InternalSubsts::identity_for_item(tcx, typeck_root_def_id));
2437 ty::InlineConstSubsts::new(tcx, ty::InlineConstSubstsParts { parent_substs, ty })
2440 let uneval = UnevaluatedConst {
2441 def: ty::WithOptConstParam::unknown(def_id).to_global(),
2445 debug_assert!(!uneval.has_free_regions());
2447 Self::Unevaluated(uneval, ty)
2450 #[instrument(skip(tcx), level = "debug", ret)]
2451 fn from_opt_const_arg_anon_const(
2453 def: ty::WithOptConstParam<LocalDefId>,
2454 param_env: ty::ParamEnv<'tcx>,
2456 let body_id = match tcx.hir().get_by_def_id(def.did) {
2457 hir::Node::AnonConst(ac) => ac.body,
2459 tcx.def_span(def.did.to_def_id()),
2460 "from_anon_const can only process anonymous constants"
2464 let expr = &tcx.hir().body(body_id).value;
2467 // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments
2468 // currently have to be wrapped in curly brackets, so it's necessary to special-case.
2469 let expr = match &expr.kind {
2470 hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => {
2471 block.expr.as_ref().unwrap()
2475 debug!("expr.kind: {:?}", expr.kind);
2477 let ty = tcx.type_of(def.def_id_for_type_of());
2480 // FIXME(const_generics): We currently have to special case parameters because `min_const_generics`
2481 // does not provide the parents generics to anonymous constants. We still allow generic const
2482 // parameters by themselves however, e.g. `N`. These constants would cause an ICE if we were to
2483 // ever try to substitute the generic parameters in their bodies.
2485 // While this doesn't happen as these constants are always used as `ty::ConstKind::Param`, it does
2486 // cause issues if we were to remove that special-case and try to evaluate the constant instead.
2487 use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath};
2489 ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => {
2490 // Find the name and index of the const parameter by indexing the generics of
2491 // the parent item and construct a `ParamConst`.
2492 let item_def_id = tcx.parent(def_id);
2493 let generics = tcx.generics_of(item_def_id);
2494 let index = generics.param_def_id_to_index[&def_id];
2495 let name = tcx.item_name(def_id);
2496 let ty_const = tcx.mk_const(ty::ParamConst::new(index, name), ty);
2499 return Self::Ty(ty_const);
2504 let hir_id = tcx.hir().local_def_id_to_hir_id(def.did);
2505 let parent_substs = if let Some(parent_hir_id) = tcx.hir().opt_parent_id(hir_id) {
2506 if let Some(parent_did) = parent_hir_id.as_owner() {
2507 InternalSubsts::identity_for_item(tcx, parent_did.to_def_id())
2509 tcx.mk_substs(Vec::<GenericArg<'tcx>>::new().into_iter())
2512 tcx.mk_substs(Vec::<GenericArg<'tcx>>::new().into_iter())
2514 debug!(?parent_substs);
2516 let did = def.did.to_def_id();
2517 let child_substs = InternalSubsts::identity_for_item(tcx, did);
2518 let substs = tcx.mk_substs(parent_substs.into_iter().chain(child_substs.into_iter()));
2521 let hir_id = tcx.hir().local_def_id_to_hir_id(def.did);
2522 let span = tcx.hir().span(hir_id);
2523 let uneval = UnevaluatedConst::new(def.to_global(), substs);
2524 debug!(?span, ?param_env);
2526 match tcx.const_eval_resolve(param_env, uneval, Some(span)) {
2528 debug!("evaluated const value");
2532 debug!("error encountered during evaluation");
2533 // Error was handled in `const_eval_resolve`. Here we just create a
2534 // new unevaluated const and error hard later in codegen
2537 def: def.to_global(),
2538 substs: InternalSubsts::identity_for_item(tcx, def.did.to_def_id()),
2547 pub fn from_const(c: ty::Const<'tcx>, tcx: TyCtxt<'tcx>) -> Self {
2549 ty::ConstKind::Value(valtree) => {
2550 let const_val = tcx.valtree_to_const_val((c.ty(), valtree));
2551 Self::Val(const_val, c.ty())
2553 ty::ConstKind::Unevaluated(uv) => Self::Unevaluated(uv.expand(), c.ty()),
2559 /// An unevaluated (potentially generic) constant used in MIR.
2560 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Lift)]
2561 #[derive(Hash, HashStable, TypeFoldable, TypeVisitable)]
2562 pub struct UnevaluatedConst<'tcx> {
2563 pub def: ty::WithOptConstParam<DefId>,
2564 pub substs: SubstsRef<'tcx>,
2565 pub promoted: Option<Promoted>,
2568 impl<'tcx> UnevaluatedConst<'tcx> {
2569 // FIXME: probably should get rid of this method. It's also wrong to
2570 // shrink and then later expand a promoted.
2572 pub fn shrink(self) -> ty::UnevaluatedConst<'tcx> {
2573 ty::UnevaluatedConst { def: self.def, substs: self.substs }
2577 impl<'tcx> UnevaluatedConst<'tcx> {
2580 def: ty::WithOptConstParam<DefId>,
2581 substs: SubstsRef<'tcx>,
2582 ) -> UnevaluatedConst<'tcx> {
2583 UnevaluatedConst { def, substs, promoted: Default::default() }
2587 /// A collection of projections into user types.
2589 /// They are projections because a binding can occur a part of a
2590 /// parent pattern that has been ascribed a type.
2592 /// Its a collection because there can be multiple type ascriptions on
2593 /// the path from the root of the pattern down to the binding itself.
2597 /// ```ignore (illustrative)
2598 /// struct S<'a>((i32, &'a str), String);
2599 /// let S((_, w): (i32, &'static str), _): S = ...;
2600 /// // ------ ^^^^^^^^^^^^^^^^^^^ (1)
2601 /// // --------------------------------- ^ (2)
2604 /// The highlights labelled `(1)` show the subpattern `(_, w)` being
2605 /// ascribed the type `(i32, &'static str)`.
2607 /// The highlights labelled `(2)` show the whole pattern being
2608 /// ascribed the type `S`.
2610 /// In this example, when we descend to `w`, we will have built up the
2611 /// following two projected types:
2613 /// * base: `S`, projection: `(base.0).1`
2614 /// * base: `(i32, &'static str)`, projection: `base.1`
2616 /// The first will lead to the constraint `w: &'1 str` (for some
2617 /// inferred region `'1`). The second will lead to the constraint `w:
2619 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
2620 pub struct UserTypeProjections {
2621 pub contents: Vec<(UserTypeProjection, Span)>,
2624 impl<'tcx> UserTypeProjections {
2625 pub fn none() -> Self {
2626 UserTypeProjections { contents: vec![] }
2629 pub fn is_empty(&self) -> bool {
2630 self.contents.is_empty()
2633 pub fn projections_and_spans(
2635 ) -> impl Iterator<Item = &(UserTypeProjection, Span)> + ExactSizeIterator {
2636 self.contents.iter()
2639 pub fn projections(&self) -> impl Iterator<Item = &UserTypeProjection> + ExactSizeIterator {
2640 self.contents.iter().map(|&(ref user_type, _span)| user_type)
2643 pub fn push_projection(mut self, user_ty: &UserTypeProjection, span: Span) -> Self {
2644 self.contents.push((user_ty.clone(), span));
2650 mut f: impl FnMut(UserTypeProjection) -> UserTypeProjection,
2652 self.contents = self.contents.into_iter().map(|(proj, span)| (f(proj), span)).collect();
2656 pub fn index(self) -> Self {
2657 self.map_projections(|pat_ty_proj| pat_ty_proj.index())
2660 pub fn subslice(self, from: u64, to: u64) -> Self {
2661 self.map_projections(|pat_ty_proj| pat_ty_proj.subslice(from, to))
2664 pub fn deref(self) -> Self {
2665 self.map_projections(|pat_ty_proj| pat_ty_proj.deref())
2668 pub fn leaf(self, field: Field) -> Self {
2669 self.map_projections(|pat_ty_proj| pat_ty_proj.leaf(field))
2672 pub fn variant(self, adt_def: AdtDef<'tcx>, variant_index: VariantIdx, field: Field) -> Self {
2673 self.map_projections(|pat_ty_proj| pat_ty_proj.variant(adt_def, variant_index, field))
2677 /// Encodes the effect of a user-supplied type annotation on the
2678 /// subcomponents of a pattern. The effect is determined by applying the
2679 /// given list of projections to some underlying base type. Often,
2680 /// the projection element list `projs` is empty, in which case this
2681 /// directly encodes a type in `base`. But in the case of complex patterns with
2682 /// subpatterns and bindings, we want to apply only a *part* of the type to a variable,
2683 /// in which case the `projs` vector is used.
2687 /// * `let x: T = ...` -- here, the `projs` vector is empty.
2689 /// * `let (x, _): T = ...` -- here, the `projs` vector would contain
2690 /// `field[0]` (aka `.0`), indicating that the type of `s` is
2691 /// determined by finding the type of the `.0` field from `T`.
2692 #[derive(Clone, Debug, TyEncodable, TyDecodable, Hash, HashStable, PartialEq)]
2693 pub struct UserTypeProjection {
2694 pub base: UserTypeAnnotationIndex,
2695 pub projs: Vec<ProjectionKind>,
2698 impl Copy for ProjectionKind {}
2700 impl UserTypeProjection {
2701 pub(crate) fn index(mut self) -> Self {
2702 self.projs.push(ProjectionElem::Index(()));
2706 pub(crate) fn subslice(mut self, from: u64, to: u64) -> Self {
2707 self.projs.push(ProjectionElem::Subslice { from, to, from_end: true });
2711 pub(crate) fn deref(mut self) -> Self {
2712 self.projs.push(ProjectionElem::Deref);
2716 pub(crate) fn leaf(mut self, field: Field) -> Self {
2717 self.projs.push(ProjectionElem::Field(field, ()));
2721 pub(crate) fn variant(
2723 adt_def: AdtDef<'_>,
2724 variant_index: VariantIdx,
2727 self.projs.push(ProjectionElem::Downcast(
2728 Some(adt_def.variant(variant_index).name),
2731 self.projs.push(ProjectionElem::Field(field, ()));
2736 impl<'tcx> TypeFoldable<'tcx> for UserTypeProjection {
2737 fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
2738 Ok(UserTypeProjection {
2739 base: self.base.try_fold_with(folder)?,
2740 projs: self.projs.try_fold_with(folder)?,
2745 impl<'tcx> TypeVisitable<'tcx> for UserTypeProjection {
2746 fn visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> ControlFlow<Vs::BreakTy> {
2747 self.base.visit_with(visitor)
2748 // Note: there's nothing in `self.proj` to visit.
2752 rustc_index::newtype_index! {
2753 #[derive(HashStable)]
2754 #[debug_format = "promoted[{}]"]
2755 pub struct Promoted {}
2758 impl<'tcx> Debug for Constant<'tcx> {
2759 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2760 write!(fmt, "{}", self)
2764 impl<'tcx> Display for Constant<'tcx> {
2765 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2766 match self.ty().kind() {
2768 _ => write!(fmt, "const ")?,
2770 Display::fmt(&self.literal, fmt)
2774 impl<'tcx> Display for ConstantKind<'tcx> {
2775 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2777 ConstantKind::Ty(c) => pretty_print_const(c, fmt, true),
2778 ConstantKind::Val(val, ty) => pretty_print_const_value(val, ty, fmt, true),
2779 // FIXME(valtrees): Correctly print mir constants.
2780 ConstantKind::Unevaluated(..) => {
2781 fmt.write_str("_")?;
2788 fn pretty_print_const<'tcx>(
2790 fmt: &mut Formatter<'_>,
2793 use crate::ty::print::PrettyPrinter;
2794 ty::tls::with(|tcx| {
2795 let literal = tcx.lift(c).unwrap();
2796 let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
2797 cx.print_alloc_ids = true;
2798 let cx = cx.pretty_print_const(literal, print_types)?;
2799 fmt.write_str(&cx.into_buffer())?;
2804 fn pretty_print_byte_str(fmt: &mut Formatter<'_>, byte_str: &[u8]) -> fmt::Result {
2805 write!(fmt, "b\"{}\"", byte_str.escape_ascii())
2808 fn comma_sep<'tcx>(fmt: &mut Formatter<'_>, elems: Vec<ConstantKind<'tcx>>) -> fmt::Result {
2809 let mut first = true;
2812 fmt.write_str(", ")?;
2814 fmt.write_str(&format!("{}", elem))?;
2820 // FIXME: Move that into `mir/pretty.rs`.
2821 fn pretty_print_const_value<'tcx>(
2822 ct: ConstValue<'tcx>,
2824 fmt: &mut Formatter<'_>,
2827 use crate::ty::print::PrettyPrinter;
2829 ty::tls::with(|tcx| {
2830 let ct = tcx.lift(ct).unwrap();
2831 let ty = tcx.lift(ty).unwrap();
2833 if tcx.sess.verbose() {
2834 fmt.write_str(&format!("ConstValue({:?}: {})", ct, ty))?;
2838 let u8_type = tcx.types.u8;
2839 match (ct, ty.kind()) {
2840 // Byte/string slices, printed as (byte) string literals.
2841 (ConstValue::Slice { data, start, end }, ty::Ref(_, inner, _)) => {
2842 match inner.kind() {
2845 // The `inspect` here is okay since we checked the bounds, and `u8` carries
2846 // no provenance (we have an active slice reference here). We don't use
2847 // this result to affect interpreter execution.
2850 .inspect_with_uninit_and_ptr_outside_interpreter(start..end);
2851 pretty_print_byte_str(fmt, byte_str)?;
2856 // The `inspect` here is okay since we checked the bounds, and `str` carries
2857 // no provenance (we have an active `str` reference here). We don't use this
2858 // result to affect interpreter execution.
2861 .inspect_with_uninit_and_ptr_outside_interpreter(start..end);
2862 fmt.write_str(&format!("{:?}", String::from_utf8_lossy(slice)))?;
2868 (ConstValue::ByRef { alloc, offset }, ty::Array(t, n)) if *t == u8_type => {
2869 let n = n.kind().try_to_bits(tcx.data_layout.pointer_size).unwrap();
2870 // cast is ok because we already checked for pointer size (32 or 64 bit) above
2871 let range = AllocRange { start: offset, size: Size::from_bytes(n) };
2872 let byte_str = alloc.inner().get_bytes_strip_provenance(&tcx, range).unwrap();
2873 fmt.write_str("*")?;
2874 pretty_print_byte_str(fmt, byte_str)?;
2877 // Aggregates, printed as array/tuple/struct/variant construction syntax.
2879 // NB: the `has_non_region_param` check ensures that we can use
2880 // the `destructure_const` query with an empty `ty::ParamEnv` without
2881 // introducing ICEs (e.g. via `layout_of`) from missing bounds.
2882 // E.g. `transmute([0usize; 2]): (u8, *mut T)` needs to know `T: Sized`
2883 // to be able to destructure the tuple into `(0u8, *mut T)
2885 // FIXME(eddyb) for `--emit=mir`/`-Z dump-mir`, we should provide the
2886 // correct `ty::ParamEnv` to allow printing *all* constant values.
2887 (_, ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) if !ty.has_non_region_param() => {
2888 let ct = tcx.lift(ct).unwrap();
2889 let ty = tcx.lift(ty).unwrap();
2890 if let Some(contents) = tcx.try_destructure_mir_constant(
2891 ty::ParamEnv::reveal_all().and(ConstantKind::Val(ct, ty)),
2893 let fields = contents.fields.to_vec();
2896 fmt.write_str("[")?;
2897 comma_sep(fmt, fields)?;
2898 fmt.write_str("]")?;
2901 fmt.write_str("(")?;
2902 comma_sep(fmt, fields)?;
2903 if contents.fields.len() == 1 {
2904 fmt.write_str(",")?;
2906 fmt.write_str(")")?;
2908 ty::Adt(def, _) if def.variants().is_empty() => {
2909 fmt.write_str(&format!("{{unreachable(): {}}}", ty))?;
2911 ty::Adt(def, substs) => {
2912 let variant_idx = contents
2914 .expect("destructed mir constant of adt without variant idx");
2915 let variant_def = &def.variant(variant_idx);
2916 let substs = tcx.lift(substs).unwrap();
2917 let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
2918 cx.print_alloc_ids = true;
2919 let cx = cx.print_value_path(variant_def.def_id, substs)?;
2920 fmt.write_str(&cx.into_buffer())?;
2922 match variant_def.ctor_kind() {
2923 Some(CtorKind::Const) => {}
2924 Some(CtorKind::Fn) => {
2925 fmt.write_str("(")?;
2926 comma_sep(fmt, fields)?;
2927 fmt.write_str(")")?;
2930 fmt.write_str(" {{ ")?;
2931 let mut first = true;
2932 for (field_def, field) in iter::zip(&variant_def.fields, fields)
2935 fmt.write_str(", ")?;
2937 fmt.write_str(&format!("{}: {}", field_def.name, field))?;
2940 fmt.write_str(" }}")?;
2944 _ => unreachable!(),
2948 // Fall back to debug pretty printing for invalid constants.
2949 fmt.write_str(&format!("{:?}", ct))?;
2951 fmt.write_str(&format!(": {}", ty))?;
2956 (ConstValue::Scalar(scalar), _) => {
2957 let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
2958 cx.print_alloc_ids = true;
2959 let ty = tcx.lift(ty).unwrap();
2960 cx = cx.pretty_print_const_scalar(scalar, ty, print_ty)?;
2961 fmt.write_str(&cx.into_buffer())?;
2964 (ConstValue::ZeroSized, ty::FnDef(d, s)) => {
2965 let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
2966 cx.print_alloc_ids = true;
2967 let cx = cx.print_value_path(*d, s)?;
2968 fmt.write_str(&cx.into_buffer())?;
2971 // FIXME(oli-obk): also pretty print arrays and other aggregate constants by reading
2972 // their fields instead of just dumping the memory.
2976 fmt.write_str(&format!("{:?}", ct))?;
2978 fmt.write_str(&format!(": {}", ty))?;
2984 /// `Location` represents the position of the start of the statement; or, if
2985 /// `statement_index` equals the number of statements, then the start of the
2987 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd, HashStable)]
2988 pub struct Location {
2989 /// The block that the location is within.
2990 pub block: BasicBlock,
2992 pub statement_index: usize,
2995 impl fmt::Debug for Location {
2996 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2997 write!(fmt, "{:?}[{}]", self.block, self.statement_index)
3002 pub const START: Location = Location { block: START_BLOCK, statement_index: 0 };
3004 /// Returns the location immediately after this one within the enclosing block.
3006 /// Note that if this location represents a terminator, then the
3007 /// resulting location would be out of bounds and invalid.
3008 pub fn successor_within_block(&self) -> Location {
3009 Location { block: self.block, statement_index: self.statement_index + 1 }
3012 /// Returns `true` if `other` is earlier in the control flow graph than `self`.
3013 pub fn is_predecessor_of<'tcx>(&self, other: Location, body: &Body<'tcx>) -> bool {
3014 // If we are in the same block as the other location and are an earlier statement
3015 // then we are a predecessor of `other`.
3016 if self.block == other.block && self.statement_index < other.statement_index {
3020 let predecessors = body.basic_blocks.predecessors();
3022 // If we're in another block, then we want to check that block is a predecessor of `other`.
3023 let mut queue: Vec<BasicBlock> = predecessors[other.block].to_vec();
3024 let mut visited = FxHashSet::default();
3026 while let Some(block) = queue.pop() {
3027 // If we haven't visited this block before, then make sure we visit its predecessors.
3028 if visited.insert(block) {
3029 queue.extend(predecessors[block].iter().cloned());
3034 // If we found the block that `self` is in, then we are a predecessor of `other` (since
3035 // we found that block by looking at the predecessors of `other`).
3036 if self.block == block {
3044 pub fn dominates(&self, other: Location, dominators: &Dominators<BasicBlock>) -> bool {
3045 if self.block == other.block {
3046 self.statement_index <= other.statement_index
3048 dominators.dominates(self.block, other.block)
3053 // Some nodes are used a lot. Make sure they don't unintentionally get bigger.
3054 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
3057 use rustc_data_structures::static_assert_size;
3058 // tidy-alphabetical-start
3059 static_assert_size!(BasicBlockData<'_>, 144);
3060 static_assert_size!(LocalDecl<'_>, 56);
3061 static_assert_size!(Statement<'_>, 32);
3062 static_assert_size!(StatementKind<'_>, 16);
3063 static_assert_size!(Terminator<'_>, 112);
3064 static_assert_size!(TerminatorKind<'_>, 96);
3065 // tidy-alphabetical-end