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::convert::TryInto;
40 use std::fmt::{self, Debug, Display, Formatter, Write};
41 use std::ops::{ControlFlow, Index, IndexMut};
44 pub use self::query::*;
45 pub use basic_blocks::BasicBlocks;
50 pub mod generic_graphviz;
51 mod graph_cyclic_cache;
65 pub use terminator::*;
72 pub use self::generic_graph::graphviz_safe_def_name;
73 pub use self::graphviz::write_mir_graphviz;
74 pub use self::pretty::{
75 create_dump_file, display_allocation, dump_enabled, dump_mir, write_mir_pretty, PassWhere,
79 pub type LocalDecls<'tcx> = IndexVec<Local, LocalDecl<'tcx>>;
81 pub trait HasLocalDecls<'tcx> {
82 fn local_decls(&self) -> &LocalDecls<'tcx>;
85 impl<'tcx> HasLocalDecls<'tcx> for LocalDecls<'tcx> {
87 fn local_decls(&self) -> &LocalDecls<'tcx> {
92 impl<'tcx> HasLocalDecls<'tcx> for Body<'tcx> {
94 fn local_decls(&self) -> &LocalDecls<'tcx> {
99 /// A streamlined trait that you can implement to create a pass; the
100 /// pass will be named after the type, and it will consist of a main
101 /// loop that goes over each available MIR and applies `run_pass`.
102 pub trait MirPass<'tcx> {
103 fn name(&self) -> &str {
104 let name = std::any::type_name::<Self>();
105 if let Some((_, tail)) = name.rsplit_once(':') { tail } else { name }
108 /// Returns `true` if this pass is enabled with the current combination of compiler flags.
109 fn is_enabled(&self, _sess: &Session) -> bool {
113 fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>);
115 fn is_mir_dump_enabled(&self) -> bool {
121 /// Gets the index of the current MirPhase within the set of all `MirPhase`s.
123 /// FIXME(JakobDegen): Return a `(usize, usize)` instead.
124 pub fn phase_index(&self) -> usize {
125 const BUILT_PHASE_COUNT: usize = 1;
126 const ANALYSIS_PHASE_COUNT: usize = 2;
128 MirPhase::Built => 1,
129 MirPhase::Analysis(analysis_phase) => {
130 1 + BUILT_PHASE_COUNT + (*analysis_phase as usize)
132 MirPhase::Runtime(runtime_phase) => {
133 1 + BUILT_PHASE_COUNT + ANALYSIS_PHASE_COUNT + (*runtime_phase as usize)
138 /// Parses an `MirPhase` from a pair of strings. Panics if this isn't possible for any reason.
139 pub fn parse(dialect: String, phase: Option<String>) -> Self {
140 match &*dialect.to_ascii_lowercase() {
142 assert!(phase.is_none(), "Cannot specify a phase for `Built` MIR");
145 "analysis" => Self::Analysis(AnalysisPhase::parse(phase)),
146 "runtime" => Self::Runtime(RuntimePhase::parse(phase)),
147 _ => panic!("Unknown MIR dialect {}", dialect),
153 pub fn parse(phase: Option<String>) -> Self {
154 let Some(phase) = phase else {
155 return Self::Initial;
158 match &*phase.to_ascii_lowercase() {
159 "initial" => Self::Initial,
160 "post_cleanup" | "post-cleanup" | "postcleanup" => Self::PostCleanup,
161 _ => panic!("Unknown analysis phase {}", phase),
167 pub fn parse(phase: Option<String>) -> Self {
168 let Some(phase) = phase else {
169 return Self::Initial;
172 match &*phase.to_ascii_lowercase() {
173 "initial" => Self::Initial,
174 "post_cleanup" | "post-cleanup" | "postcleanup" => Self::PostCleanup,
175 "optimized" => Self::Optimized,
176 _ => panic!("Unknown runtime phase {}", phase),
181 /// Where a specific `mir::Body` comes from.
182 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
183 #[derive(HashStable, TyEncodable, TyDecodable, TypeFoldable, TypeVisitable)]
184 pub struct MirSource<'tcx> {
185 pub instance: InstanceDef<'tcx>,
187 /// If `Some`, this is a promoted rvalue within the parent function.
188 pub promoted: Option<Promoted>,
191 impl<'tcx> MirSource<'tcx> {
192 pub fn item(def_id: DefId) -> Self {
194 instance: InstanceDef::Item(ty::WithOptConstParam::unknown(def_id)),
199 pub fn from_instance(instance: InstanceDef<'tcx>) -> Self {
200 MirSource { instance, promoted: None }
203 pub fn with_opt_param(self) -> ty::WithOptConstParam<DefId> {
204 self.instance.with_opt_param()
208 pub fn def_id(&self) -> DefId {
209 self.instance.def_id()
213 #[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable, TypeVisitable)]
214 pub struct GeneratorInfo<'tcx> {
215 /// The yield type of the function, if it is a generator.
216 pub yield_ty: Option<Ty<'tcx>>,
218 /// Generator drop glue.
219 pub generator_drop: Option<Body<'tcx>>,
221 /// The layout of a generator. Produced by the state transformation.
222 pub generator_layout: Option<GeneratorLayout<'tcx>>,
224 /// If this is a generator then record the type of source expression that caused this generator
226 pub generator_kind: GeneratorKind,
229 /// The lowered representation of a single function.
230 #[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable, TypeVisitable)]
231 pub struct Body<'tcx> {
232 /// A list of basic blocks. References to basic block use a newtyped index type [`BasicBlock`]
233 /// that indexes into this vector.
234 pub basic_blocks: BasicBlocks<'tcx>,
236 /// Records how far through the "desugaring and optimization" process this particular
237 /// MIR has traversed. This is particularly useful when inlining, since in that context
238 /// we instantiate the promoted constants and add them to our promoted vector -- but those
239 /// promoted items have already been optimized, whereas ours have not. This field allows
240 /// us to see the difference and forego optimization on the inlined promoted items.
243 /// How many passses we have executed since starting the current phase. Used for debug output.
244 pub pass_count: usize,
246 pub source: MirSource<'tcx>,
248 /// A list of source scopes; these are referenced by statements
249 /// and used for debuginfo. Indexed by a `SourceScope`.
250 pub source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
252 pub generator: Option<Box<GeneratorInfo<'tcx>>>,
254 /// Declarations of locals.
256 /// The first local is the return value pointer, followed by `arg_count`
257 /// locals for the function arguments, followed by any user-declared
258 /// variables and temporaries.
259 pub local_decls: LocalDecls<'tcx>,
261 /// User type annotations.
262 pub user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
264 /// The number of arguments this function takes.
266 /// Starting at local 1, `arg_count` locals will be provided by the caller
267 /// and can be assumed to be initialized.
269 /// If this MIR was built for a constant, this will be 0.
270 pub arg_count: usize,
272 /// Mark an argument local (which must be a tuple) as getting passed as
273 /// its individual components at the LLVM level.
275 /// This is used for the "rust-call" ABI.
276 pub spread_arg: Option<Local>,
278 /// Debug information pertaining to user variables, including captures.
279 pub var_debug_info: Vec<VarDebugInfo<'tcx>>,
281 /// A span representing this MIR, for error reporting.
284 /// Constants that are required to evaluate successfully for this MIR to be well-formed.
285 /// We hold in this field all the constants we are not able to evaluate yet.
286 pub required_consts: Vec<Constant<'tcx>>,
288 /// Does this body use generic parameters. This is used for the `ConstEvaluatable` check.
290 /// Note that this does not actually mean that this body is not computable right now.
291 /// The repeat count in the following example is polymorphic, but can still be evaluated
292 /// without knowing anything about the type parameter `T`.
296 /// let _ = [0; std::mem::size_of::<*mut T>()];
300 /// **WARNING**: Do not change this flags after the MIR was originally created, even if an optimization
301 /// removed the last mention of all generic params. We do not want to rely on optimizations and
302 /// potentially allow things like `[u8; std::mem::size_of::<T>() * 0]` due to this.
303 pub is_polymorphic: bool,
305 /// The phase at which this MIR should be "injected" into the compilation process.
307 /// Everything that comes before this `MirPhase` should be skipped.
309 /// This is only `Some` if the function that this body comes from was annotated with `rustc_custom_mir`.
310 pub injection_phase: Option<MirPhase>,
312 pub tainted_by_errors: Option<ErrorGuaranteed>,
315 impl<'tcx> Body<'tcx> {
317 source: MirSource<'tcx>,
318 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
319 source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
320 local_decls: LocalDecls<'tcx>,
321 user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
323 var_debug_info: Vec<VarDebugInfo<'tcx>>,
325 generator_kind: Option<GeneratorKind>,
326 tainted_by_errors: Option<ErrorGuaranteed>,
328 // We need `arg_count` locals, and one for the return place.
330 local_decls.len() > arg_count,
331 "expected at least {} locals, got {}",
336 let mut body = Body {
337 phase: MirPhase::Built,
340 basic_blocks: BasicBlocks::new(basic_blocks),
342 generator: generator_kind.map(|generator_kind| {
343 Box::new(GeneratorInfo {
345 generator_drop: None,
346 generator_layout: None,
351 user_type_annotations,
356 required_consts: Vec::new(),
357 is_polymorphic: false,
358 injection_phase: None,
361 body.is_polymorphic = body.has_non_region_param();
365 /// Returns a partially initialized MIR body containing only a list of basic blocks.
367 /// The returned MIR contains no `LocalDecl`s (even for the return place) or source scopes. It
368 /// is only useful for testing but cannot be `#[cfg(test)]` because it is used in a different
370 pub fn new_cfg_only(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>) -> Self {
371 let mut body = Body {
372 phase: MirPhase::Built,
374 source: MirSource::item(CRATE_DEF_ID.to_def_id()),
375 basic_blocks: BasicBlocks::new(basic_blocks),
376 source_scopes: IndexVec::new(),
378 local_decls: IndexVec::new(),
379 user_type_annotations: IndexVec::new(),
383 required_consts: Vec::new(),
384 var_debug_info: Vec::new(),
385 is_polymorphic: false,
386 injection_phase: None,
387 tainted_by_errors: None,
389 body.is_polymorphic = body.has_non_region_param();
394 pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
395 self.basic_blocks.as_mut()
399 pub fn local_kind(&self, local: Local) -> LocalKind {
400 let index = local.as_usize();
403 self.local_decls[local].mutability == Mutability::Mut,
404 "return place should be mutable"
407 LocalKind::ReturnPointer
408 } else if index < self.arg_count + 1 {
410 } else if self.local_decls[local].is_user_variable() {
417 /// Returns an iterator over all user-declared mutable locals.
419 pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + Captures<'tcx> + 'a {
420 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
421 let local = Local::new(index);
422 let decl = &self.local_decls[local];
423 if decl.is_user_variable() && decl.mutability == Mutability::Mut {
431 /// Returns an iterator over all user-declared mutable arguments and locals.
433 pub fn mut_vars_and_args_iter<'a>(
435 ) -> impl Iterator<Item = Local> + Captures<'tcx> + 'a {
436 (1..self.local_decls.len()).filter_map(move |index| {
437 let local = Local::new(index);
438 let decl = &self.local_decls[local];
439 if (decl.is_user_variable() || index < self.arg_count + 1)
440 && decl.mutability == Mutability::Mut
449 /// Returns an iterator over all function arguments.
451 pub fn args_iter(&self) -> impl Iterator<Item = Local> + ExactSizeIterator {
452 (1..self.arg_count + 1).map(Local::new)
455 /// Returns an iterator over all user-defined variables and compiler-generated temporaries (all
456 /// locals that are neither arguments nor the return place).
458 pub fn vars_and_temps_iter(
460 ) -> impl DoubleEndedIterator<Item = Local> + ExactSizeIterator {
461 (self.arg_count + 1..self.local_decls.len()).map(Local::new)
465 pub fn drain_vars_and_temps<'a>(&'a mut self) -> impl Iterator<Item = LocalDecl<'tcx>> + 'a {
466 self.local_decls.drain(self.arg_count + 1..)
469 /// Returns the source info associated with `location`.
470 pub fn source_info(&self, location: Location) -> &SourceInfo {
471 let block = &self[location.block];
472 let stmts = &block.statements;
473 let idx = location.statement_index;
474 if idx < stmts.len() {
475 &stmts[idx].source_info
477 assert_eq!(idx, stmts.len());
478 &block.terminator().source_info
482 /// Returns the return type; it always return first element from `local_decls` array.
484 pub fn return_ty(&self) -> Ty<'tcx> {
485 self.local_decls[RETURN_PLACE].ty
488 /// Returns the return type; it always return first element from `local_decls` array.
490 pub fn bound_return_ty(&self) -> ty::EarlyBinder<Ty<'tcx>> {
491 ty::EarlyBinder(self.local_decls[RETURN_PLACE].ty)
494 /// Gets the location of the terminator for the given block.
496 pub fn terminator_loc(&self, bb: BasicBlock) -> Location {
497 Location { block: bb, statement_index: self[bb].statements.len() }
500 pub fn stmt_at(&self, location: Location) -> Either<&Statement<'tcx>, &Terminator<'tcx>> {
501 let Location { block, statement_index } = location;
502 let block_data = &self.basic_blocks[block];
505 .get(statement_index)
507 .unwrap_or_else(|| Either::Right(block_data.terminator()))
511 pub fn yield_ty(&self) -> Option<Ty<'tcx>> {
512 self.generator.as_ref().and_then(|generator| generator.yield_ty)
516 pub fn generator_layout(&self) -> Option<&GeneratorLayout<'tcx>> {
517 self.generator.as_ref().and_then(|generator| generator.generator_layout.as_ref())
521 pub fn generator_drop(&self) -> Option<&Body<'tcx>> {
522 self.generator.as_ref().and_then(|generator| generator.generator_drop.as_ref())
526 pub fn generator_kind(&self) -> Option<GeneratorKind> {
527 self.generator.as_ref().map(|generator| generator.generator_kind)
531 pub fn should_skip(&self) -> bool {
532 let Some(injection_phase) = self.injection_phase else {
535 injection_phase > self.phase
539 #[derive(Copy, Clone, PartialEq, Eq, Debug, TyEncodable, TyDecodable, HashStable)]
542 /// Unsafe because of compiler-generated unsafe code, like `await` desugaring
544 /// Unsafe because of an unsafe fn
546 /// Unsafe because of an `unsafe` block
547 ExplicitUnsafe(hir::HirId),
550 impl<'tcx> Index<BasicBlock> for Body<'tcx> {
551 type Output = BasicBlockData<'tcx>;
554 fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
555 &self.basic_blocks[index]
559 impl<'tcx> IndexMut<BasicBlock> for Body<'tcx> {
561 fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> {
562 &mut self.basic_blocks.as_mut()[index]
566 #[derive(Copy, Clone, Debug, HashStable, TypeFoldable, TypeVisitable)]
567 pub enum ClearCrossCrate<T> {
572 impl<T> ClearCrossCrate<T> {
573 pub fn as_ref(&self) -> ClearCrossCrate<&T> {
575 ClearCrossCrate::Clear => ClearCrossCrate::Clear,
576 ClearCrossCrate::Set(v) => ClearCrossCrate::Set(v),
580 pub fn assert_crate_local(self) -> T {
582 ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"),
583 ClearCrossCrate::Set(v) => v,
588 const TAG_CLEAR_CROSS_CRATE_CLEAR: u8 = 0;
589 const TAG_CLEAR_CROSS_CRATE_SET: u8 = 1;
591 impl<E: TyEncoder, T: Encodable<E>> Encodable<E> for ClearCrossCrate<T> {
593 fn encode(&self, e: &mut E) {
594 if E::CLEAR_CROSS_CRATE {
599 ClearCrossCrate::Clear => TAG_CLEAR_CROSS_CRATE_CLEAR.encode(e),
600 ClearCrossCrate::Set(ref val) => {
601 TAG_CLEAR_CROSS_CRATE_SET.encode(e);
607 impl<D: TyDecoder, T: Decodable<D>> Decodable<D> for ClearCrossCrate<T> {
609 fn decode(d: &mut D) -> ClearCrossCrate<T> {
610 if D::CLEAR_CROSS_CRATE {
611 return ClearCrossCrate::Clear;
614 let discr = u8::decode(d);
617 TAG_CLEAR_CROSS_CRATE_CLEAR => ClearCrossCrate::Clear,
618 TAG_CLEAR_CROSS_CRATE_SET => {
619 let val = T::decode(d);
620 ClearCrossCrate::Set(val)
622 tag => panic!("Invalid tag for ClearCrossCrate: {:?}", tag),
627 /// Grouped information about the source code origin of a MIR entity.
628 /// Intended to be inspected by diagnostics and debuginfo.
629 /// Most passes can work with it as a whole, within a single function.
630 // The unofficial Cranelift backend, at least as of #65828, needs `SourceInfo` to implement `Eq` and
631 // `Hash`. Please ping @bjorn3 if removing them.
632 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)]
633 pub struct SourceInfo {
634 /// The source span for the AST pertaining to this MIR entity.
637 /// The source scope, keeping track of which bindings can be
638 /// seen by debuginfo, active lint levels, `unsafe {...}`, etc.
639 pub scope: SourceScope,
644 pub fn outermost(span: Span) -> Self {
645 SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE }
649 ///////////////////////////////////////////////////////////////////////////
650 // Variables and temps
652 rustc_index::newtype_index! {
655 DEBUG_FORMAT = "_{}",
656 const RETURN_PLACE = 0,
660 impl Atom for Local {
661 fn index(self) -> usize {
666 /// Classifies locals into categories. See `Body::local_kind`.
667 #[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable)]
669 /// User-declared variable binding.
671 /// Compiler-introduced temporary.
673 /// Function argument.
675 /// Location of function's return value.
679 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
680 pub struct VarBindingForm<'tcx> {
681 /// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`?
682 pub binding_mode: ty::BindingMode,
683 /// If an explicit type was provided for this variable binding,
684 /// this holds the source Span of that type.
686 /// NOTE: if you want to change this to a `HirId`, be wary that
687 /// doing so breaks incremental compilation (as of this writing),
688 /// while a `Span` does not cause our tests to fail.
689 pub opt_ty_info: Option<Span>,
690 /// Place of the RHS of the =, or the subject of the `match` where this
691 /// variable is initialized. None in the case of `let PATTERN;`.
692 /// Some((None, ..)) in the case of and `let [mut] x = ...` because
693 /// (a) the right-hand side isn't evaluated as a place expression.
694 /// (b) it gives a way to separate this case from the remaining cases
696 pub opt_match_place: Option<(Option<Place<'tcx>>, Span)>,
697 /// The span of the pattern in which this variable was bound.
701 #[derive(Clone, Debug, TyEncodable, TyDecodable)]
702 pub enum BindingForm<'tcx> {
703 /// This is a binding for a non-`self` binding, or a `self` that has an explicit type.
704 Var(VarBindingForm<'tcx>),
705 /// Binding for a `self`/`&self`/`&mut self` binding where the type is implicit.
706 ImplicitSelf(ImplicitSelfKind),
707 /// Reference used in a guard expression to ensure immutability.
711 TrivialTypeTraversalAndLiftImpls! { BindingForm<'tcx>, }
713 mod binding_form_impl {
714 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
715 use rustc_query_system::ich::StableHashingContext;
717 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
718 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
719 use super::BindingForm::*;
720 std::mem::discriminant(self).hash_stable(hcx, hasher);
723 Var(binding) => binding.hash_stable(hcx, hasher),
724 ImplicitSelf(kind) => kind.hash_stable(hcx, hasher),
731 /// `BlockTailInfo` is attached to the `LocalDecl` for temporaries
732 /// created during evaluation of expressions in a block tail
733 /// expression; that is, a block like `{ STMT_1; STMT_2; EXPR }`.
735 /// It is used to improve diagnostics when such temporaries are
736 /// involved in borrow_check errors, e.g., explanations of where the
737 /// temporaries come from, when their destructors are run, and/or how
738 /// one might revise the code to satisfy the borrow checker's rules.
739 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
740 pub struct BlockTailInfo {
741 /// If `true`, then the value resulting from evaluating this tail
742 /// expression is ignored by the block's expression context.
744 /// Examples include `{ ...; tail };` and `let _ = { ...; tail };`
745 /// but not e.g., `let _x = { ...; tail };`
746 pub tail_result_is_ignored: bool,
748 /// `Span` of the tail expression.
754 /// This can be a binding declared by the user, a temporary inserted by the compiler, a function
755 /// argument, or the return place.
756 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
757 pub struct LocalDecl<'tcx> {
758 /// Whether this is a mutable binding (i.e., `let x` or `let mut x`).
760 /// Temporaries and the return place are always mutable.
761 pub mutability: Mutability,
763 // FIXME(matthewjasper) Don't store in this in `Body`
764 pub local_info: Option<Box<LocalInfo<'tcx>>>,
766 /// `true` if this is an internal local.
768 /// These locals are not based on types in the source code and are only used
769 /// for a few desugarings at the moment.
771 /// The generator transformation will sanity check the locals which are live
772 /// across a suspension point against the type components of the generator
773 /// which type checking knows are live across a suspension point. We need to
774 /// flag drop flags to avoid triggering this check as they are introduced
775 /// outside of type inference.
777 /// This should be sound because the drop flags are fully algebraic, and
778 /// therefore don't affect the auto-trait or outlives properties of the
782 /// If this local is a temporary and `is_block_tail` is `Some`,
783 /// then it is a temporary created for evaluation of some
784 /// subexpression of some block's tail expression (with no
785 /// intervening statement context).
786 // FIXME(matthewjasper) Don't store in this in `Body`
787 pub is_block_tail: Option<BlockTailInfo>,
789 /// The type of this local.
792 /// If the user manually ascribed a type to this variable,
793 /// e.g., via `let x: T`, then we carry that type here. The MIR
794 /// borrow checker needs this information since it can affect
795 /// region inference.
796 // FIXME(matthewjasper) Don't store in this in `Body`
797 pub user_ty: Option<Box<UserTypeProjections>>,
799 /// The *syntactic* (i.e., not visibility) source scope the local is defined
800 /// in. If the local was defined in a let-statement, this
801 /// is *within* the let-statement, rather than outside
804 /// This is needed because the visibility source scope of locals within
805 /// a let-statement is weird.
807 /// The reason is that we want the local to be *within* the let-statement
808 /// for lint purposes, but we want the local to be *after* the let-statement
809 /// for names-in-scope purposes.
811 /// That's it, if we have a let-statement like the one in this
815 /// fn foo(x: &str) {
816 /// #[allow(unused_mut)]
817 /// let mut x: u32 = { // <- one unused mut
818 /// let mut y: u32 = x.parse().unwrap();
825 /// Then, from a lint point of view, the declaration of `x: u32`
826 /// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the
827 /// lint scopes are the same as the AST/HIR nesting.
829 /// However, from a name lookup point of view, the scopes look more like
830 /// as if the let-statements were `match` expressions:
833 /// fn foo(x: &str) {
835 /// match x.parse::<u32>().unwrap() {
844 /// We care about the name-lookup scopes for debuginfo - if the
845 /// debuginfo instruction pointer is at the call to `x.parse()`, we
846 /// want `x` to refer to `x: &str`, but if it is at the call to
847 /// `drop(x)`, we want it to refer to `x: u32`.
849 /// To allow both uses to work, we need to have more than a single scope
850 /// for a local. We have the `source_info.scope` represent the "syntactic"
851 /// lint scope (with a variable being under its let block) while the
852 /// `var_debug_info.source_info.scope` represents the "local variable"
853 /// scope (where the "rest" of a block is under all prior let-statements).
855 /// The end result looks like this:
859 /// │{ argument x: &str }
861 /// │ │{ #[allow(unused_mut)] } // This is actually split into 2 scopes
862 /// │ │ // in practice because I'm lazy.
864 /// │ │← x.source_info.scope
865 /// │ │← `x.parse().unwrap()`
867 /// │ │ │← y.source_info.scope
869 /// │ │ │{ let y: u32 }
871 /// │ │ │← y.var_debug_info.source_info.scope
874 /// │ │{ let x: u32 }
875 /// │ │← x.var_debug_info.source_info.scope
876 /// │ │← `drop(x)` // This accesses `x: u32`.
878 pub source_info: SourceInfo,
881 /// Extra information about a some locals that's used for diagnostics and for
882 /// classifying variables into local variables, statics, etc, which is needed e.g.
883 /// for unsafety checking.
885 /// Not used for non-StaticRef temporaries, the return place, or anonymous
886 /// function parameters.
887 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
888 pub enum LocalInfo<'tcx> {
889 /// A user-defined local variable or function parameter
891 /// The `BindingForm` is solely used for local diagnostics when generating
892 /// warnings/errors when compiling the current crate, and therefore it need
893 /// not be visible across crates.
894 User(ClearCrossCrate<BindingForm<'tcx>>),
895 /// A temporary created that references the static with the given `DefId`.
896 StaticRef { def_id: DefId, is_thread_local: bool },
897 /// A temporary created that references the const with the given `DefId`
898 ConstRef { def_id: DefId },
899 /// A temporary created during the creation of an aggregate
900 /// (e.g. a temporary for `foo` in `MyStruct { my_field: foo }`)
902 /// A temporary created during the pass `Derefer` to avoid it's retagging
906 impl<'tcx> LocalDecl<'tcx> {
907 /// Returns `true` only if local is a binding that can itself be
908 /// made mutable via the addition of the `mut` keyword, namely
909 /// something like the occurrences of `x` in:
910 /// - `fn foo(x: Type) { ... }`,
912 /// - or `match ... { C(x) => ... }`
913 pub fn can_be_made_mutable(&self) -> bool {
916 Some(box LocalInfo::User(ClearCrossCrate::Set(
917 BindingForm::Var(VarBindingForm {
918 binding_mode: ty::BindingMode::BindByValue(_),
922 }) | BindingForm::ImplicitSelf(ImplicitSelfKind::Imm),
927 /// Returns `true` if local is definitely not a `ref ident` or
928 /// `ref mut ident` binding. (Such bindings cannot be made into
929 /// mutable bindings, but the inverse does not necessarily hold).
930 pub fn is_nonref_binding(&self) -> bool {
933 Some(box LocalInfo::User(ClearCrossCrate::Set(
934 BindingForm::Var(VarBindingForm {
935 binding_mode: ty::BindingMode::BindByValue(_),
939 }) | BindingForm::ImplicitSelf(_),
944 /// Returns `true` if this variable is a named variable or function
945 /// parameter declared by the user.
947 pub fn is_user_variable(&self) -> bool {
948 matches!(self.local_info, Some(box LocalInfo::User(_)))
951 /// Returns `true` if this is a reference to a variable bound in a `match`
952 /// expression that is used to access said variable for the guard of the
954 pub fn is_ref_for_guard(&self) -> bool {
957 Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::RefForGuard)))
961 /// Returns `Some` if this is a reference to a static item that is used to
962 /// access that static.
963 pub fn is_ref_to_static(&self) -> bool {
964 matches!(self.local_info, Some(box LocalInfo::StaticRef { .. }))
967 /// Returns `Some` if this is a reference to a thread-local static item that is used to
968 /// access that static.
969 pub fn is_ref_to_thread_local(&self) -> bool {
970 match self.local_info {
971 Some(box LocalInfo::StaticRef { is_thread_local, .. }) => is_thread_local,
976 /// Returns `true` if this is a DerefTemp
977 pub fn is_deref_temp(&self) -> bool {
978 match self.local_info {
979 Some(box LocalInfo::DerefTemp) => return true,
985 /// Returns `true` is the local is from a compiler desugaring, e.g.,
986 /// `__next` from a `for` loop.
988 pub fn from_compiler_desugaring(&self) -> bool {
989 self.source_info.span.desugaring_kind().is_some()
992 /// Creates a new `LocalDecl` for a temporary: mutable, non-internal.
994 pub fn new(ty: Ty<'tcx>, span: Span) -> Self {
995 Self::with_source_info(ty, SourceInfo::outermost(span))
998 /// Like `LocalDecl::new`, but takes a `SourceInfo` instead of a `Span`.
1000 pub fn with_source_info(ty: Ty<'tcx>, source_info: SourceInfo) -> Self {
1002 mutability: Mutability::Mut,
1005 is_block_tail: None,
1012 /// Converts `self` into same `LocalDecl` except tagged as internal.
1014 pub fn internal(mut self) -> Self {
1015 self.internal = true;
1019 /// Converts `self` into same `LocalDecl` except tagged as immutable.
1021 pub fn immutable(mut self) -> Self {
1022 self.mutability = Mutability::Not;
1026 /// Converts `self` into same `LocalDecl` except tagged as internal temporary.
1028 pub fn block_tail(mut self, info: BlockTailInfo) -> Self {
1029 assert!(self.is_block_tail.is_none());
1030 self.is_block_tail = Some(info);
1035 #[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1036 pub enum VarDebugInfoContents<'tcx> {
1037 /// NOTE(eddyb) There's an unenforced invariant that this `Place` is
1038 /// based on a `Local`, not a `Static`, and contains no indexing.
1040 Const(Constant<'tcx>),
1041 /// The user variable's data is split across several fragments,
1042 /// each described by a `VarDebugInfoFragment`.
1043 /// See DWARF 5's "2.6.1.2 Composite Location Descriptions"
1044 /// and LLVM's `DW_OP_LLVM_fragment` for more details on
1045 /// the underlying debuginfo feature this relies on.
1047 /// Type of the original user variable.
1049 /// All the parts of the original user variable, which ended
1050 /// up in disjoint places, due to optimizations.
1051 fragments: Vec<VarDebugInfoFragment<'tcx>>,
1055 impl<'tcx> Debug for VarDebugInfoContents<'tcx> {
1056 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1058 VarDebugInfoContents::Const(c) => write!(fmt, "{}", c),
1059 VarDebugInfoContents::Place(p) => write!(fmt, "{:?}", p),
1060 VarDebugInfoContents::Composite { ty, fragments } => {
1061 write!(fmt, "{:?}{{ ", ty)?;
1062 for f in fragments.iter() {
1063 write!(fmt, "{:?}, ", f)?;
1071 #[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1072 pub struct VarDebugInfoFragment<'tcx> {
1073 /// Where in the composite user variable this fragment is,
1074 /// represented as a "projection" into the composite variable.
1075 /// At lower levels, this corresponds to a byte/bit range.
1076 // NOTE(eddyb) there's an unenforced invariant that this contains
1077 // only `Field`s, and not into `enum` variants or `union`s.
1078 // FIXME(eddyb) support this for `enum`s by either using DWARF's
1079 // more advanced control-flow features (unsupported by LLVM?)
1080 // to match on the discriminant, or by using custom type debuginfo
1081 // with non-overlapping variants for the composite variable.
1082 pub projection: Vec<PlaceElem<'tcx>>,
1084 /// Where the data for this fragment can be found.
1085 // NOTE(eddyb) There's an unenforced invariant that this `Place` is
1086 // contains no indexing (with a non-constant index).
1087 pub contents: Place<'tcx>,
1090 impl Debug for VarDebugInfoFragment<'_> {
1091 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1092 for elem in self.projection.iter() {
1094 ProjectionElem::Field(field, _) => {
1095 write!(fmt, ".{:?}", field.index())?;
1097 _ => bug!("unsupported fragment projection `{:?}`", elem),
1101 write!(fmt, " => {:?}", self.contents)
1105 /// Debug information pertaining to a user variable.
1106 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1107 pub struct VarDebugInfo<'tcx> {
1110 /// Source info of the user variable, including the scope
1111 /// within which the variable is visible (to debuginfo)
1112 /// (see `LocalDecl`'s `source_info` field for more details).
1113 pub source_info: SourceInfo,
1115 /// Where the data for this user variable is to be found.
1116 pub value: VarDebugInfoContents<'tcx>,
1119 ///////////////////////////////////////////////////////////////////////////
1122 rustc_index::newtype_index! {
1123 /// A node in the MIR [control-flow graph][CFG].
1125 /// There are no branches (e.g., `if`s, function calls, etc.) within a basic block, which makes
1126 /// it easier to do [data-flow analyses] and optimizations. Instead, branches are represented
1127 /// as an edge in a graph between basic blocks.
1129 /// Basic blocks consist of a series of [statements][Statement], ending with a
1130 /// [terminator][Terminator]. Basic blocks can have multiple predecessors and successors,
1131 /// however there is a MIR pass ([`CriticalCallEdges`]) that removes *critical edges*, which
1132 /// are edges that go from a multi-successor node to a multi-predecessor node. This pass is
1133 /// needed because some analyses require that there are no critical edges in the CFG.
1135 /// Note that this type is just an index into [`Body.basic_blocks`](Body::basic_blocks);
1136 /// the actual data that a basic block holds is in [`BasicBlockData`].
1138 /// Read more about basic blocks in the [rustc-dev-guide][guide-mir].
1140 /// [CFG]: https://rustc-dev-guide.rust-lang.org/appendix/background.html#cfg
1141 /// [data-flow analyses]:
1142 /// https://rustc-dev-guide.rust-lang.org/appendix/background.html#what-is-a-dataflow-analysis
1143 /// [`CriticalCallEdges`]: ../../rustc_const_eval/transform/add_call_guards/enum.AddCallGuards.html#variant.CriticalCallEdges
1144 /// [guide-mir]: https://rustc-dev-guide.rust-lang.org/mir/
1145 pub struct BasicBlock {
1147 DEBUG_FORMAT = "bb{}",
1148 const START_BLOCK = 0,
1153 pub fn start_location(self) -> Location {
1154 Location { block: self, statement_index: 0 }
1158 ///////////////////////////////////////////////////////////////////////////
1161 /// Data for a basic block, including a list of its statements.
1163 /// See [`BasicBlock`] for documentation on what basic blocks are at a high level.
1164 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1165 pub struct BasicBlockData<'tcx> {
1166 /// List of statements in this block.
1167 pub statements: Vec<Statement<'tcx>>,
1169 /// Terminator for this block.
1171 /// N.B., this should generally ONLY be `None` during construction.
1172 /// Therefore, you should generally access it via the
1173 /// `terminator()` or `terminator_mut()` methods. The only
1174 /// exception is that certain passes, such as `simplify_cfg`, swap
1175 /// out the terminator temporarily with `None` while they continue
1176 /// to recurse over the set of basic blocks.
1177 pub terminator: Option<Terminator<'tcx>>,
1179 /// If true, this block lies on an unwind path. This is used
1180 /// during codegen where distinct kinds of basic blocks may be
1181 /// generated (particularly for MSVC cleanup). Unwind blocks must
1182 /// only branch to other unwind blocks.
1183 pub is_cleanup: bool,
1186 impl<'tcx> BasicBlockData<'tcx> {
1187 pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
1188 BasicBlockData { statements: vec![], terminator, is_cleanup: false }
1191 /// Accessor for terminator.
1193 /// Terminator may not be None after construction of the basic block is complete. This accessor
1194 /// provides a convenient way to reach the terminator.
1196 pub fn terminator(&self) -> &Terminator<'tcx> {
1197 self.terminator.as_ref().expect("invalid terminator state")
1201 pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
1202 self.terminator.as_mut().expect("invalid terminator state")
1205 pub fn retain_statements<F>(&mut self, mut f: F)
1207 F: FnMut(&mut Statement<'_>) -> bool,
1209 for s in &mut self.statements {
1216 pub fn expand_statements<F, I>(&mut self, mut f: F)
1218 F: FnMut(&mut Statement<'tcx>) -> Option<I>,
1219 I: iter::TrustedLen<Item = Statement<'tcx>>,
1221 // Gather all the iterators we'll need to splice in, and their positions.
1222 let mut splices: Vec<(usize, I)> = vec![];
1223 let mut extra_stmts = 0;
1224 for (i, s) in self.statements.iter_mut().enumerate() {
1225 if let Some(mut new_stmts) = f(s) {
1226 if let Some(first) = new_stmts.next() {
1227 // We can already store the first new statement.
1230 // Save the other statements for optimized splicing.
1231 let remaining = new_stmts.size_hint().0;
1233 splices.push((i + 1 + extra_stmts, new_stmts));
1234 extra_stmts += remaining;
1242 // Splice in the new statements, from the end of the block.
1243 // FIXME(eddyb) This could be more efficient with a "gap buffer"
1244 // where a range of elements ("gap") is left uninitialized, with
1245 // splicing adding new elements to the end of that gap and moving
1246 // existing elements from before the gap to the end of the gap.
1247 // For now, this is safe code, emulating a gap but initializing it.
1248 let mut gap = self.statements.len()..self.statements.len() + extra_stmts;
1249 self.statements.resize(
1251 Statement { source_info: SourceInfo::outermost(DUMMY_SP), kind: StatementKind::Nop },
1253 for (splice_start, new_stmts) in splices.into_iter().rev() {
1254 let splice_end = splice_start + new_stmts.size_hint().0;
1255 while gap.end > splice_end {
1258 self.statements.swap(gap.start, gap.end);
1260 self.statements.splice(splice_start..splice_end, new_stmts);
1261 gap.end = splice_start;
1265 pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
1266 if index < self.statements.len() { &self.statements[index] } else { &self.terminator }
1269 /// Does the block have no statements and an unreachable terminator?
1270 pub fn is_empty_unreachable(&self) -> bool {
1271 self.statements.is_empty() && matches!(self.terminator().kind, TerminatorKind::Unreachable)
1275 impl<O> AssertKind<O> {
1276 /// Getting a description does not require `O` to be printable, and does not
1277 /// require allocation.
1278 /// The caller is expected to handle `BoundsCheck` separately.
1279 pub fn description(&self) -> &'static str {
1282 Overflow(BinOp::Add, _, _) => "attempt to add with overflow",
1283 Overflow(BinOp::Sub, _, _) => "attempt to subtract with overflow",
1284 Overflow(BinOp::Mul, _, _) => "attempt to multiply with overflow",
1285 Overflow(BinOp::Div, _, _) => "attempt to divide with overflow",
1286 Overflow(BinOp::Rem, _, _) => "attempt to calculate the remainder with overflow",
1287 OverflowNeg(_) => "attempt to negate with overflow",
1288 Overflow(BinOp::Shr, _, _) => "attempt to shift right with overflow",
1289 Overflow(BinOp::Shl, _, _) => "attempt to shift left with overflow",
1290 Overflow(op, _, _) => bug!("{:?} cannot overflow", op),
1291 DivisionByZero(_) => "attempt to divide by zero",
1292 RemainderByZero(_) => "attempt to calculate the remainder with a divisor of zero",
1293 ResumedAfterReturn(GeneratorKind::Gen) => "generator resumed after completion",
1294 ResumedAfterReturn(GeneratorKind::Async(_)) => "`async fn` resumed after completion",
1295 ResumedAfterPanic(GeneratorKind::Gen) => "generator resumed after panicking",
1296 ResumedAfterPanic(GeneratorKind::Async(_)) => "`async fn` resumed after panicking",
1297 BoundsCheck { .. } => bug!("Unexpected AssertKind"),
1301 /// Format the message arguments for the `assert(cond, msg..)` terminator in MIR printing.
1302 pub fn fmt_assert_args<W: Write>(&self, f: &mut W) -> fmt::Result
1308 BoundsCheck { ref len, ref index } => write!(
1310 "\"index out of bounds: the length is {{}} but the index is {{}}\", {:?}, {:?}",
1314 OverflowNeg(op) => {
1315 write!(f, "\"attempt to negate `{{}}`, which would overflow\", {:?}", op)
1317 DivisionByZero(op) => write!(f, "\"attempt to divide `{{}}` by zero\", {:?}", op),
1318 RemainderByZero(op) => write!(
1320 "\"attempt to calculate the remainder of `{{}}` with a divisor of zero\", {:?}",
1323 Overflow(BinOp::Add, l, r) => write!(
1325 "\"attempt to compute `{{}} + {{}}`, which would overflow\", {:?}, {:?}",
1328 Overflow(BinOp::Sub, l, r) => write!(
1330 "\"attempt to compute `{{}} - {{}}`, which would overflow\", {:?}, {:?}",
1333 Overflow(BinOp::Mul, l, r) => write!(
1335 "\"attempt to compute `{{}} * {{}}`, which would overflow\", {:?}, {:?}",
1338 Overflow(BinOp::Div, l, r) => write!(
1340 "\"attempt to compute `{{}} / {{}}`, which would overflow\", {:?}, {:?}",
1343 Overflow(BinOp::Rem, l, r) => write!(
1345 "\"attempt to compute the remainder of `{{}} % {{}}`, which would overflow\", {:?}, {:?}",
1348 Overflow(BinOp::Shr, _, r) => {
1349 write!(f, "\"attempt to shift right by `{{}}`, which would overflow\", {:?}", r)
1351 Overflow(BinOp::Shl, _, r) => {
1352 write!(f, "\"attempt to shift left by `{{}}`, which would overflow\", {:?}", r)
1354 _ => write!(f, "\"{}\"", self.description()),
1359 impl<O: fmt::Debug> fmt::Debug for AssertKind<O> {
1360 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1363 BoundsCheck { ref len, ref index } => write!(
1365 "index out of bounds: the length is {:?} but the index is {:?}",
1368 OverflowNeg(op) => write!(f, "attempt to negate `{:#?}`, which would overflow", op),
1369 DivisionByZero(op) => write!(f, "attempt to divide `{:#?}` by zero", op),
1370 RemainderByZero(op) => write!(
1372 "attempt to calculate the remainder of `{:#?}` with a divisor of zero",
1375 Overflow(BinOp::Add, l, r) => {
1376 write!(f, "attempt to compute `{:#?} + {:#?}`, which would overflow", l, r)
1378 Overflow(BinOp::Sub, l, r) => {
1379 write!(f, "attempt to compute `{:#?} - {:#?}`, which would overflow", l, r)
1381 Overflow(BinOp::Mul, l, r) => {
1382 write!(f, "attempt to compute `{:#?} * {:#?}`, which would overflow", l, r)
1384 Overflow(BinOp::Div, l, r) => {
1385 write!(f, "attempt to compute `{:#?} / {:#?}`, which would overflow", l, r)
1387 Overflow(BinOp::Rem, l, r) => write!(
1389 "attempt to compute the remainder of `{:#?} % {:#?}`, which would overflow",
1392 Overflow(BinOp::Shr, _, r) => {
1393 write!(f, "attempt to shift right by `{:#?}`, which would overflow", r)
1395 Overflow(BinOp::Shl, _, r) => {
1396 write!(f, "attempt to shift left by `{:#?}`, which would overflow", r)
1398 _ => write!(f, "{}", self.description()),
1403 ///////////////////////////////////////////////////////////////////////////
1406 /// A statement in a basic block, including information about its source code.
1407 #[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1408 pub struct Statement<'tcx> {
1409 pub source_info: SourceInfo,
1410 pub kind: StatementKind<'tcx>,
1413 impl Statement<'_> {
1414 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
1415 /// invalidating statement indices in `Location`s.
1416 pub fn make_nop(&mut self) {
1417 self.kind = StatementKind::Nop
1420 /// Changes a statement to a nop and returns the original statement.
1421 #[must_use = "If you don't need the statement, use `make_nop` instead"]
1422 pub fn replace_nop(&mut self) -> Self {
1424 source_info: self.source_info,
1425 kind: mem::replace(&mut self.kind, StatementKind::Nop),
1430 impl Debug for Statement<'_> {
1431 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1432 use self::StatementKind::*;
1434 Assign(box (ref place, ref rv)) => write!(fmt, "{:?} = {:?}", place, rv),
1435 FakeRead(box (ref cause, ref place)) => {
1436 write!(fmt, "FakeRead({:?}, {:?})", cause, place)
1438 Retag(ref kind, ref place) => write!(
1442 RetagKind::FnEntry => "[fn entry] ",
1443 RetagKind::TwoPhase => "[2phase] ",
1444 RetagKind::Raw => "[raw] ",
1445 RetagKind::Default => "",
1449 StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place),
1450 StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place),
1451 SetDiscriminant { ref place, variant_index } => {
1452 write!(fmt, "discriminant({:?}) = {:?}", place, variant_index)
1454 Deinit(ref place) => write!(fmt, "Deinit({:?})", place),
1455 AscribeUserType(box (ref place, ref c_ty), ref variance) => {
1456 write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty)
1458 Coverage(box self::Coverage { ref kind, code_region: Some(ref rgn) }) => {
1459 write!(fmt, "Coverage::{:?} for {:?}", kind, rgn)
1461 Coverage(box ref coverage) => write!(fmt, "Coverage::{:?}", coverage.kind),
1462 Intrinsic(box ref intrinsic) => write!(fmt, "{intrinsic}"),
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
1531 DEBUG_FORMAT = "field[{}]"
1535 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
1536 pub struct PlaceRef<'tcx> {
1538 pub projection: &'tcx [PlaceElem<'tcx>],
1541 // Once we stop implementing `Ord` for `DefId`,
1542 // this impl will be unnecessary. Until then, we'll
1543 // leave this impl in place to prevent re-adding a
1544 // dependency on the `Ord` impl for `DefId`
1545 impl<'tcx> !PartialOrd for PlaceRef<'tcx> {}
1547 impl<'tcx> Place<'tcx> {
1548 // FIXME change this to a const fn by also making List::empty a const fn.
1549 pub fn return_place() -> Place<'tcx> {
1550 Place { local: RETURN_PLACE, projection: List::empty() }
1553 /// Returns `true` if this `Place` contains a `Deref` projection.
1555 /// If `Place::is_indirect` returns false, the caller knows that the `Place` refers to the
1556 /// same region of memory as its base.
1557 pub fn is_indirect(&self) -> bool {
1558 self.projection.iter().any(|elem| elem.is_indirect())
1561 /// If MirPhase >= Derefered and if projection contains Deref,
1562 /// It's guaranteed to be in the first place
1563 pub fn has_deref(&self) -> bool {
1564 // To make sure this is not accidentally used in wrong mir phase
1566 self.projection.is_empty() || !self.projection[1..].contains(&PlaceElem::Deref)
1568 self.projection.first() == Some(&PlaceElem::Deref)
1571 /// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
1572 /// a single deref of a local.
1574 pub fn local_or_deref_local(&self) -> Option<Local> {
1575 self.as_ref().local_or_deref_local()
1578 /// If this place represents a local variable like `_X` with no
1579 /// projections, return `Some(_X)`.
1581 pub fn as_local(&self) -> Option<Local> {
1582 self.as_ref().as_local()
1586 pub fn as_ref(&self) -> PlaceRef<'tcx> {
1587 PlaceRef { local: self.local, projection: &self.projection }
1590 /// Iterate over the projections in evaluation order, i.e., the first element is the base with
1591 /// its projection and then subsequently more projections are added.
1592 /// As a concrete example, given the place a.b.c, this would yield:
1596 /// Given a place without projections, the iterator is empty.
1598 pub fn iter_projections(
1600 ) -> impl Iterator<Item = (PlaceRef<'tcx>, PlaceElem<'tcx>)> + DoubleEndedIterator {
1601 self.as_ref().iter_projections()
1604 /// Generates a new place by appending `more_projections` to the existing ones
1605 /// and interning the result.
1606 pub fn project_deeper(self, more_projections: &[PlaceElem<'tcx>], tcx: TyCtxt<'tcx>) -> Self {
1607 if more_projections.is_empty() {
1611 let mut v: Vec<PlaceElem<'tcx>>;
1613 let new_projections = if self.projection.is_empty() {
1616 v = Vec::with_capacity(self.projection.len() + more_projections.len());
1617 v.extend(self.projection);
1618 v.extend(more_projections);
1622 Place { local: self.local, projection: tcx.intern_place_elems(new_projections) }
1626 impl From<Local> for Place<'_> {
1628 fn from(local: Local) -> Self {
1629 Place { local, projection: List::empty() }
1633 impl<'tcx> PlaceRef<'tcx> {
1634 /// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
1635 /// a single deref of a local.
1636 pub fn local_or_deref_local(&self) -> Option<Local> {
1638 PlaceRef { local, projection: [] }
1639 | PlaceRef { local, projection: [ProjectionElem::Deref] } => Some(local),
1644 /// If MirPhase >= Derefered and if projection contains Deref,
1645 /// It's guaranteed to be in the first place
1646 pub fn has_deref(&self) -> bool {
1647 self.projection.first() == Some(&PlaceElem::Deref)
1650 /// If this place represents a local variable like `_X` with no
1651 /// projections, return `Some(_X)`.
1653 pub fn as_local(&self) -> Option<Local> {
1655 PlaceRef { local, projection: [] } => Some(local),
1661 pub fn last_projection(&self) -> Option<(PlaceRef<'tcx>, PlaceElem<'tcx>)> {
1662 if let &[ref proj_base @ .., elem] = self.projection {
1663 Some((PlaceRef { local: self.local, projection: proj_base }, elem))
1669 /// Iterate over the projections in evaluation order, i.e., the first element is the base with
1670 /// its projection and then subsequently more projections are added.
1671 /// As a concrete example, given the place a.b.c, this would yield:
1675 /// Given a place without projections, the iterator is empty.
1677 pub fn iter_projections(
1679 ) -> impl Iterator<Item = (PlaceRef<'tcx>, PlaceElem<'tcx>)> + DoubleEndedIterator {
1680 self.projection.iter().enumerate().map(move |(i, proj)| {
1681 let base = PlaceRef { local: self.local, projection: &self.projection[..i] };
1687 impl Debug for Place<'_> {
1688 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1689 for elem in self.projection.iter().rev() {
1691 ProjectionElem::OpaqueCast(_)
1692 | ProjectionElem::Downcast(_, _)
1693 | ProjectionElem::Field(_, _) => {
1694 write!(fmt, "(").unwrap();
1696 ProjectionElem::Deref => {
1697 write!(fmt, "(*").unwrap();
1699 ProjectionElem::Index(_)
1700 | ProjectionElem::ConstantIndex { .. }
1701 | ProjectionElem::Subslice { .. } => {}
1705 write!(fmt, "{:?}", self.local)?;
1707 for elem in self.projection.iter() {
1709 ProjectionElem::OpaqueCast(ty) => {
1710 write!(fmt, " as {})", ty)?;
1712 ProjectionElem::Downcast(Some(name), _index) => {
1713 write!(fmt, " as {})", name)?;
1715 ProjectionElem::Downcast(None, index) => {
1716 write!(fmt, " as variant#{:?})", index)?;
1718 ProjectionElem::Deref => {
1721 ProjectionElem::Field(field, ty) => {
1722 write!(fmt, ".{:?}: {:?})", field.index(), ty)?;
1724 ProjectionElem::Index(ref index) => {
1725 write!(fmt, "[{:?}]", index)?;
1727 ProjectionElem::ConstantIndex { offset, min_length, from_end: false } => {
1728 write!(fmt, "[{:?} of {:?}]", offset, min_length)?;
1730 ProjectionElem::ConstantIndex { offset, min_length, from_end: true } => {
1731 write!(fmt, "[-{:?} of {:?}]", offset, min_length)?;
1733 ProjectionElem::Subslice { from, to, from_end: true } if to == 0 => {
1734 write!(fmt, "[{:?}:]", from)?;
1736 ProjectionElem::Subslice { from, to, from_end: true } if from == 0 => {
1737 write!(fmt, "[:-{:?}]", to)?;
1739 ProjectionElem::Subslice { from, to, from_end: true } => {
1740 write!(fmt, "[{:?}:-{:?}]", from, to)?;
1742 ProjectionElem::Subslice { from, to, from_end: false } => {
1743 write!(fmt, "[{:?}..{:?}]", from, to)?;
1752 ///////////////////////////////////////////////////////////////////////////
1755 rustc_index::newtype_index! {
1756 pub struct SourceScope {
1758 DEBUG_FORMAT = "scope[{}]",
1759 const OUTERMOST_SOURCE_SCOPE = 0,
1764 /// Finds the original HirId this MIR item came from.
1765 /// This is necessary after MIR optimizations, as otherwise we get a HirId
1766 /// from the function that was inlined instead of the function call site.
1767 pub fn lint_root<'tcx>(
1769 source_scopes: &IndexVec<SourceScope, SourceScopeData<'tcx>>,
1770 ) -> Option<HirId> {
1771 let mut data = &source_scopes[self];
1772 // FIXME(oli-obk): we should be able to just walk the `inlined_parent_scope`, but it
1773 // does not work as I thought it would. Needs more investigation and documentation.
1774 while data.inlined.is_some() {
1776 data = &source_scopes[data.parent_scope.unwrap()];
1779 match &data.local_data {
1780 ClearCrossCrate::Set(data) => Some(data.lint_root),
1781 ClearCrossCrate::Clear => None,
1785 /// The instance this source scope was inlined from, if any.
1787 pub fn inlined_instance<'tcx>(
1789 source_scopes: &IndexVec<SourceScope, SourceScopeData<'tcx>>,
1790 ) -> Option<ty::Instance<'tcx>> {
1791 let scope_data = &source_scopes[self];
1792 if let Some((inlined_instance, _)) = scope_data.inlined {
1793 Some(inlined_instance)
1794 } else if let Some(inlined_scope) = scope_data.inlined_parent_scope {
1795 Some(source_scopes[inlined_scope].inlined.unwrap().0)
1802 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
1803 pub struct SourceScopeData<'tcx> {
1805 pub parent_scope: Option<SourceScope>,
1807 /// Whether this scope is the root of a scope tree of another body,
1808 /// inlined into this body by the MIR inliner.
1809 /// `ty::Instance` is the callee, and the `Span` is the call site.
1810 pub inlined: Option<(ty::Instance<'tcx>, Span)>,
1812 /// Nearest (transitive) parent scope (if any) which is inlined.
1813 /// This is an optimization over walking up `parent_scope`
1814 /// until a scope with `inlined: Some(...)` is found.
1815 pub inlined_parent_scope: Option<SourceScope>,
1817 /// Crate-local information for this source scope, that can't (and
1818 /// needn't) be tracked across crates.
1819 pub local_data: ClearCrossCrate<SourceScopeLocalData>,
1822 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
1823 pub struct SourceScopeLocalData {
1824 /// An `HirId` with lint levels equivalent to this scope's lint levels.
1825 pub lint_root: hir::HirId,
1826 /// The unsafe block that contains this node.
1830 ///////////////////////////////////////////////////////////////////////////
1833 impl<'tcx> Debug for Operand<'tcx> {
1834 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1835 use self::Operand::*;
1837 Constant(ref a) => write!(fmt, "{:?}", a),
1838 Copy(ref place) => write!(fmt, "{:?}", place),
1839 Move(ref place) => write!(fmt, "move {:?}", place),
1844 impl<'tcx> Operand<'tcx> {
1845 /// Convenience helper to make a constant that refers to the fn
1846 /// with given `DefId` and substs. Since this is used to synthesize
1847 /// MIR, assumes `user_ty` is None.
1848 pub fn function_handle(
1851 substs: SubstsRef<'tcx>,
1854 let ty = tcx.mk_fn_def(def_id, substs);
1855 Operand::Constant(Box::new(Constant {
1858 literal: ConstantKind::Val(ConstValue::ZeroSized, ty),
1862 pub fn is_move(&self) -> bool {
1863 matches!(self, Operand::Move(..))
1866 /// Convenience helper to make a literal-like constant from a given scalar value.
1867 /// Since this is used to synthesize MIR, assumes `user_ty` is None.
1868 pub fn const_from_scalar(
1873 ) -> Operand<'tcx> {
1875 let param_env_and_ty = ty::ParamEnv::empty().and(ty);
1877 .layout_of(param_env_and_ty)
1878 .unwrap_or_else(|e| panic!("could not compute layout for {:?}: {:?}", ty, e))
1880 let scalar_size = match val {
1881 Scalar::Int(int) => int.size(),
1882 _ => panic!("Invalid scalar type {:?}", val),
1884 scalar_size == type_size
1886 Operand::Constant(Box::new(Constant {
1889 literal: ConstantKind::Val(ConstValue::Scalar(val), ty),
1893 pub fn to_copy(&self) -> Self {
1895 Operand::Copy(_) | Operand::Constant(_) => self.clone(),
1896 Operand::Move(place) => Operand::Copy(place),
1900 /// Returns the `Place` that is the target of this `Operand`, or `None` if this `Operand` is a
1902 pub fn place(&self) -> Option<Place<'tcx>> {
1904 Operand::Copy(place) | Operand::Move(place) => Some(*place),
1905 Operand::Constant(_) => None,
1909 /// Returns the `Constant` that is the target of this `Operand`, or `None` if this `Operand` is a
1911 pub fn constant(&self) -> Option<&Constant<'tcx>> {
1913 Operand::Constant(x) => Some(&**x),
1914 Operand::Copy(_) | Operand::Move(_) => None,
1918 /// Gets the `ty::FnDef` from an operand if it's a constant function item.
1920 /// While this is unlikely in general, it's the normal case of what you'll
1921 /// find as the `func` in a [`TerminatorKind::Call`].
1922 pub fn const_fn_def(&self) -> Option<(DefId, SubstsRef<'tcx>)> {
1923 let const_ty = self.constant()?.literal.ty();
1924 if let ty::FnDef(def_id, substs) = *const_ty.kind() { Some((def_id, substs)) } else { None }
1928 ///////////////////////////////////////////////////////////////////////////
1931 impl<'tcx> Rvalue<'tcx> {
1932 /// Returns true if rvalue can be safely removed when the result is unused.
1934 pub fn is_safe_to_remove(&self) -> bool {
1936 // Pointer to int casts may be side-effects due to exposing the provenance.
1937 // While the model is undecided, we should be conservative. See
1938 // <https://www.ralfj.de/blog/2022/04/11/provenance-exposed.html>
1939 Rvalue::Cast(CastKind::PointerExposeAddress, _, _) => false,
1942 | Rvalue::CopyForDeref(_)
1943 | Rvalue::Repeat(_, _)
1944 | Rvalue::Ref(_, _, _)
1945 | Rvalue::ThreadLocalRef(_)
1946 | Rvalue::AddressOf(_, _)
1950 | CastKind::FloatToInt
1951 | CastKind::FloatToFloat
1952 | CastKind::IntToFloat
1953 | CastKind::FnPtrToPtr
1954 | CastKind::PtrToPtr
1955 | CastKind::Pointer(_)
1956 | CastKind::PointerFromExposedAddress
1957 | CastKind::DynStar,
1961 | Rvalue::BinaryOp(_, _)
1962 | Rvalue::CheckedBinaryOp(_, _)
1963 | Rvalue::NullaryOp(_, _)
1964 | Rvalue::UnaryOp(_, _)
1965 | Rvalue::Discriminant(_)
1966 | Rvalue::Aggregate(_, _)
1967 | Rvalue::ShallowInitBox(_, _) => true,
1973 pub fn allows_two_phase_borrow(&self) -> bool {
1975 BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => false,
1976 BorrowKind::Mut { allow_two_phase_borrow } => allow_two_phase_borrow,
1980 // FIXME: won't be used after diagnostic migration
1981 pub fn describe_mutability(&self) -> &str {
1983 BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => "immutable",
1984 BorrowKind::Mut { .. } => "mutable",
1990 pub fn is_checkable(self) -> bool {
1992 matches!(self, Add | Sub | Mul | Shl | Shr)
1996 impl<'tcx> Debug for Rvalue<'tcx> {
1997 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1998 use self::Rvalue::*;
2001 Use(ref place) => write!(fmt, "{:?}", place),
2002 Repeat(ref a, b) => {
2003 write!(fmt, "[{:?}; ", a)?;
2004 pretty_print_const(b, fmt, false)?;
2007 Len(ref a) => write!(fmt, "Len({:?})", a),
2008 Cast(ref kind, ref place, ref ty) => {
2009 write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind)
2011 BinaryOp(ref op, box (ref a, ref b)) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
2012 CheckedBinaryOp(ref op, box (ref a, ref b)) => {
2013 write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b)
2015 UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
2016 Discriminant(ref place) => write!(fmt, "discriminant({:?})", place),
2017 NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
2018 ThreadLocalRef(did) => ty::tls::with(|tcx| {
2019 let muta = tcx.static_mutability(did).unwrap().prefix_str();
2020 write!(fmt, "&/*tls*/ {}{}", muta, tcx.def_path_str(did))
2022 Ref(region, borrow_kind, ref place) => {
2023 let kind_str = match borrow_kind {
2024 BorrowKind::Shared => "",
2025 BorrowKind::Shallow => "shallow ",
2026 BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ",
2029 // When printing regions, add trailing space if necessary.
2030 let print_region = ty::tls::with(|tcx| {
2031 tcx.sess.verbose() || tcx.sess.opts.unstable_opts.identify_regions
2033 let region = if print_region {
2034 let mut region = region.to_string();
2035 if !region.is_empty() {
2040 // Do not even print 'static
2043 write!(fmt, "&{}{}{:?}", region, kind_str, place)
2046 CopyForDeref(ref place) => write!(fmt, "deref_copy {:#?}", place),
2048 AddressOf(mutability, ref place) => {
2049 let kind_str = match mutability {
2050 Mutability::Mut => "mut",
2051 Mutability::Not => "const",
2054 write!(fmt, "&raw {} {:?}", kind_str, place)
2057 Aggregate(ref kind, ref places) => {
2058 let fmt_tuple = |fmt: &mut Formatter<'_>, name: &str| {
2059 let mut tuple_fmt = fmt.debug_tuple(name);
2060 for place in places {
2061 tuple_fmt.field(place);
2067 AggregateKind::Array(_) => write!(fmt, "{:?}", places),
2069 AggregateKind::Tuple => {
2070 if places.is_empty() {
2077 AggregateKind::Adt(adt_did, variant, substs, _user_ty, _) => {
2078 ty::tls::with(|tcx| {
2079 let variant_def = &tcx.adt_def(adt_did).variant(variant);
2080 let substs = tcx.lift(substs).expect("could not lift for printing");
2081 let name = FmtPrinter::new(tcx, Namespace::ValueNS)
2082 .print_def_path(variant_def.def_id, substs)?
2085 match variant_def.ctor_kind() {
2086 Some(CtorKind::Const) => fmt.write_str(&name),
2087 Some(CtorKind::Fn) => fmt_tuple(fmt, &name),
2089 let mut struct_fmt = fmt.debug_struct(&name);
2090 for (field, place) in iter::zip(&variant_def.fields, places) {
2091 struct_fmt.field(field.name.as_str(), place);
2099 AggregateKind::Closure(def_id, substs) => ty::tls::with(|tcx| {
2100 let name = if tcx.sess.opts.unstable_opts.span_free_formats {
2101 let substs = tcx.lift(substs).unwrap();
2104 tcx.def_path_str_with_substs(def_id.to_def_id(), substs),
2107 let span = tcx.def_span(def_id);
2110 tcx.sess.source_map().span_to_diagnostic_string(span)
2113 let mut struct_fmt = fmt.debug_struct(&name);
2115 // FIXME(project-rfc-2229#48): This should be a list of capture names/places
2116 if let Some(upvars) = tcx.upvars_mentioned(def_id) {
2117 for (&var_id, place) in iter::zip(upvars.keys(), places) {
2118 let var_name = tcx.hir().name(var_id);
2119 struct_fmt.field(var_name.as_str(), place);
2126 AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
2127 let name = format!("[generator@{:?}]", tcx.def_span(def_id));
2128 let mut struct_fmt = fmt.debug_struct(&name);
2130 // FIXME(project-rfc-2229#48): This should be a list of capture names/places
2131 if let Some(upvars) = tcx.upvars_mentioned(def_id) {
2132 for (&var_id, place) in iter::zip(upvars.keys(), places) {
2133 let var_name = tcx.hir().name(var_id);
2134 struct_fmt.field(var_name.as_str(), place);
2143 ShallowInitBox(ref place, ref ty) => {
2144 write!(fmt, "ShallowInitBox({:?}, {:?})", place, ty)
2150 ///////////////////////////////////////////////////////////////////////////
2153 /// Two constants are equal if they are the same constant. Note that
2154 /// this does not necessarily mean that they are `==` in Rust. In
2155 /// particular, one must be wary of `NaN`!
2157 #[derive(Clone, Copy, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)]
2158 #[derive(TypeFoldable, TypeVisitable)]
2159 pub struct Constant<'tcx> {
2162 /// Optional user-given type: for something like
2163 /// `collect::<Vec<_>>`, this would be present and would
2164 /// indicate that `Vec<_>` was explicitly specified.
2166 /// Needed for NLL to impose user-given type constraints.
2167 pub user_ty: Option<UserTypeAnnotationIndex>,
2169 pub literal: ConstantKind<'tcx>,
2172 #[derive(Clone, Copy, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable, Debug)]
2173 #[derive(Lift, TypeFoldable, TypeVisitable)]
2174 pub enum ConstantKind<'tcx> {
2175 /// This constant came from the type system
2176 Ty(ty::Const<'tcx>),
2178 /// An unevaluated mir constant which is not part of the type system.
2179 Unevaluated(UnevaluatedConst<'tcx>, Ty<'tcx>),
2181 /// This constant cannot go back into the type system, as it represents
2182 /// something the type system cannot handle (e.g. pointers).
2183 Val(interpret::ConstValue<'tcx>, Ty<'tcx>),
2186 impl<'tcx> Constant<'tcx> {
2187 pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option<DefId> {
2188 match self.literal.try_to_scalar() {
2189 Some(Scalar::Ptr(ptr, _size)) => match tcx.global_alloc(ptr.provenance) {
2190 GlobalAlloc::Static(def_id) => {
2191 assert!(!tcx.is_thread_local_static(def_id));
2200 pub fn ty(&self) -> Ty<'tcx> {
2205 impl<'tcx> ConstantKind<'tcx> {
2207 pub fn ty(&self) -> Ty<'tcx> {
2209 ConstantKind::Ty(c) => c.ty(),
2210 ConstantKind::Val(_, ty) | ConstantKind::Unevaluated(_, ty) => *ty,
2215 pub fn try_to_value(self, tcx: TyCtxt<'tcx>) -> Option<interpret::ConstValue<'tcx>> {
2217 ConstantKind::Ty(c) => match c.kind() {
2218 ty::ConstKind::Value(valtree) => Some(tcx.valtree_to_const_val((c.ty(), valtree))),
2221 ConstantKind::Val(val, _) => Some(val),
2222 ConstantKind::Unevaluated(..) => None,
2227 pub fn try_to_scalar(self) -> Option<Scalar> {
2229 ConstantKind::Ty(c) => match c.kind() {
2230 ty::ConstKind::Value(valtree) => match valtree {
2231 ty::ValTree::Leaf(scalar_int) => Some(Scalar::Int(scalar_int)),
2232 ty::ValTree::Branch(_) => None,
2236 ConstantKind::Val(val, _) => val.try_to_scalar(),
2237 ConstantKind::Unevaluated(..) => None,
2242 pub fn try_to_scalar_int(self) -> Option<ScalarInt> {
2243 Some(self.try_to_scalar()?.assert_int())
2247 pub fn try_to_bits(self, size: Size) -> Option<u128> {
2248 self.try_to_scalar_int()?.to_bits(size).ok()
2252 pub fn try_to_bool(self) -> Option<bool> {
2253 self.try_to_scalar_int()?.try_into().ok()
2257 pub fn eval(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self {
2260 if let Some(val) = c.kind().try_eval_for_mir(tcx, param_env) {
2262 Ok(val) => Self::Val(val, c.ty()),
2263 Err(_) => Self::Ty(tcx.const_error(self.ty())),
2269 Self::Val(_, _) => self,
2270 Self::Unevaluated(uneval, ty) => {
2271 // FIXME: We might want to have a `try_eval`-like function on `Unevaluated`
2272 match tcx.const_eval_resolve(param_env, uneval, None) {
2273 Ok(val) => Self::Val(val, ty),
2274 Err(ErrorHandled::TooGeneric) => self,
2275 Err(ErrorHandled::Reported(guar)) => {
2276 Self::Ty(tcx.const_error_with_guaranteed(ty, guar))
2283 /// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type.
2285 pub fn eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 {
2286 self.try_eval_bits(tcx, param_env, ty)
2287 .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self))
2291 pub fn try_eval_bits(
2294 param_env: ty::ParamEnv<'tcx>,
2298 Self::Ty(ct) => ct.try_eval_bits(tcx, param_env, ty),
2299 Self::Val(val, t) => {
2302 tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size;
2303 val.try_to_bits(size)
2305 Self::Unevaluated(uneval, ty) => {
2306 match tcx.const_eval_resolve(param_env, *uneval, None) {
2309 .layout_of(param_env.with_reveal_all_normalized(tcx).and(*ty))
2312 val.try_to_bits(size)
2321 pub fn try_eval_bool(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Option<bool> {
2323 Self::Ty(ct) => ct.try_eval_bool(tcx, param_env),
2324 Self::Val(val, _) => val.try_to_bool(),
2325 Self::Unevaluated(uneval, _) => {
2326 match tcx.const_eval_resolve(param_env, *uneval, None) {
2327 Ok(val) => val.try_to_bool(),
2335 pub fn try_eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Option<u64> {
2337 Self::Ty(ct) => ct.try_eval_usize(tcx, param_env),
2338 Self::Val(val, _) => val.try_to_machine_usize(tcx),
2339 Self::Unevaluated(uneval, _) => {
2340 match tcx.const_eval_resolve(param_env, *uneval, None) {
2341 Ok(val) => val.try_to_machine_usize(tcx),
2349 pub fn from_value(val: ConstValue<'tcx>, ty: Ty<'tcx>) -> Self {
2356 param_env_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
2359 .layout_of(param_env_ty)
2360 .unwrap_or_else(|e| {
2361 bug!("could not compute layout for {:?}: {:?}", param_env_ty.value, e)
2364 let cv = ConstValue::Scalar(Scalar::from_uint(bits, size));
2366 Self::Val(cv, param_env_ty.value)
2370 pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> Self {
2371 let cv = ConstValue::from_bool(v);
2372 Self::Val(cv, tcx.types.bool)
2376 pub fn zero_sized(ty: Ty<'tcx>) -> Self {
2377 let cv = ConstValue::ZeroSized;
2381 pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self {
2382 let ty = tcx.types.usize;
2383 Self::from_bits(tcx, n as u128, ty::ParamEnv::empty().and(ty))
2387 pub fn from_scalar(_tcx: TyCtxt<'tcx>, s: Scalar, ty: Ty<'tcx>) -> Self {
2388 let val = ConstValue::Scalar(s);
2392 /// Literals are converted to `ConstantKindVal`, const generic parameters are eagerly
2393 /// converted to a constant, everything else becomes `Unevaluated`.
2394 pub fn from_anon_const(
2397 param_env: ty::ParamEnv<'tcx>,
2399 Self::from_opt_const_arg_anon_const(tcx, ty::WithOptConstParam::unknown(def_id), param_env)
2402 #[instrument(skip(tcx), level = "debug", ret)]
2403 pub fn from_inline_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
2404 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
2405 let body_id = match tcx.hir().get(hir_id) {
2406 hir::Node::AnonConst(ac) => ac.body,
2408 tcx.def_span(def_id.to_def_id()),
2409 "from_inline_const can only process anonymous constants"
2412 let expr = &tcx.hir().body(body_id).value;
2413 let ty = tcx.typeck(def_id).node_type(hir_id);
2415 let lit_input = match expr.kind {
2416 hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
2417 hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => match expr.kind {
2418 hir::ExprKind::Lit(ref lit) => {
2419 Some(LitToConstInput { lit: &lit.node, ty, neg: true })
2425 if let Some(lit_input) = lit_input {
2426 // If an error occurred, ignore that it's a literal and leave reporting the error up to
2428 match tcx.at(expr.span).lit_to_mir_constant(lit_input) {
2434 let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id());
2436 tcx.erase_regions(InternalSubsts::identity_for_item(tcx, typeck_root_def_id));
2438 ty::InlineConstSubsts::new(tcx, ty::InlineConstSubstsParts { parent_substs, ty })
2441 let uneval = UnevaluatedConst {
2442 def: ty::WithOptConstParam::unknown(def_id).to_global(),
2446 debug_assert!(!uneval.has_free_regions());
2448 Self::Unevaluated(uneval, ty)
2451 #[instrument(skip(tcx), level = "debug", ret)]
2452 fn from_opt_const_arg_anon_const(
2454 def: ty::WithOptConstParam<LocalDefId>,
2455 param_env: ty::ParamEnv<'tcx>,
2457 let body_id = match tcx.hir().get_by_def_id(def.did) {
2458 hir::Node::AnonConst(ac) => ac.body,
2460 tcx.def_span(def.did.to_def_id()),
2461 "from_anon_const can only process anonymous constants"
2465 let expr = &tcx.hir().body(body_id).value;
2468 // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments
2469 // currently have to be wrapped in curly brackets, so it's necessary to special-case.
2470 let expr = match &expr.kind {
2471 hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => {
2472 block.expr.as_ref().unwrap()
2476 debug!("expr.kind: {:?}", expr.kind);
2478 let ty = tcx.type_of(def.def_id_for_type_of());
2481 // FIXME(const_generics): We currently have to special case parameters because `min_const_generics`
2482 // does not provide the parents generics to anonymous constants. We still allow generic const
2483 // parameters by themselves however, e.g. `N`. These constants would cause an ICE if we were to
2484 // ever try to substitute the generic parameters in their bodies.
2486 // While this doesn't happen as these constants are always used as `ty::ConstKind::Param`, it does
2487 // cause issues if we were to remove that special-case and try to evaluate the constant instead.
2488 use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath};
2490 ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => {
2491 // Find the name and index of the const parameter by indexing the generics of
2492 // the parent item and construct a `ParamConst`.
2493 let item_def_id = tcx.parent(def_id);
2494 let generics = tcx.generics_of(item_def_id);
2495 let index = generics.param_def_id_to_index[&def_id];
2496 let name = tcx.item_name(def_id);
2497 let ty_const = tcx.mk_const(ty::ParamConst::new(index, name), ty);
2500 return Self::Ty(ty_const);
2505 let hir_id = tcx.hir().local_def_id_to_hir_id(def.did);
2506 let parent_substs = if let Some(parent_hir_id) = tcx.hir().find_parent_node(hir_id) {
2507 if let Some(parent_did) = tcx.hir().opt_local_def_id(parent_hir_id) {
2508 InternalSubsts::identity_for_item(tcx, parent_did.to_def_id())
2510 tcx.mk_substs(Vec::<GenericArg<'tcx>>::new().into_iter())
2513 tcx.mk_substs(Vec::<GenericArg<'tcx>>::new().into_iter())
2515 debug!(?parent_substs);
2517 let did = def.did.to_def_id();
2518 let child_substs = InternalSubsts::identity_for_item(tcx, did);
2519 let substs = tcx.mk_substs(parent_substs.into_iter().chain(child_substs.into_iter()));
2522 let hir_id = tcx.hir().local_def_id_to_hir_id(def.did);
2523 let span = tcx.hir().span(hir_id);
2524 let uneval = UnevaluatedConst::new(def.to_global(), substs);
2525 debug!(?span, ?param_env);
2527 match tcx.const_eval_resolve(param_env, uneval, Some(span)) {
2529 debug!("evaluated const value");
2533 debug!("error encountered during evaluation");
2534 // Error was handled in `const_eval_resolve`. Here we just create a
2535 // new unevaluated const and error hard later in codegen
2538 def: def.to_global(),
2539 substs: InternalSubsts::identity_for_item(tcx, def.did.to_def_id()),
2548 pub fn from_const(c: ty::Const<'tcx>, tcx: TyCtxt<'tcx>) -> Self {
2550 ty::ConstKind::Value(valtree) => {
2551 let const_val = tcx.valtree_to_const_val((c.ty(), valtree));
2552 Self::Val(const_val, c.ty())
2554 ty::ConstKind::Unevaluated(uv) => Self::Unevaluated(uv.expand(), c.ty()),
2560 /// An unevaluated (potentially generic) constant used in MIR.
2561 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Lift)]
2562 #[derive(Hash, HashStable, TypeFoldable, TypeVisitable)]
2563 pub struct UnevaluatedConst<'tcx> {
2564 pub def: ty::WithOptConstParam<DefId>,
2565 pub substs: SubstsRef<'tcx>,
2566 pub promoted: Option<Promoted>,
2569 impl<'tcx> UnevaluatedConst<'tcx> {
2570 // FIXME: probably should get rid of this method. It's also wrong to
2571 // shrink and then later expand a promoted.
2573 pub fn shrink(self) -> ty::UnevaluatedConst<'tcx> {
2574 ty::UnevaluatedConst { def: self.def, substs: self.substs }
2578 impl<'tcx> UnevaluatedConst<'tcx> {
2581 def: ty::WithOptConstParam<DefId>,
2582 substs: SubstsRef<'tcx>,
2583 ) -> UnevaluatedConst<'tcx> {
2584 UnevaluatedConst { def, substs, promoted: Default::default() }
2588 /// A collection of projections into user types.
2590 /// They are projections because a binding can occur a part of a
2591 /// parent pattern that has been ascribed a type.
2593 /// Its a collection because there can be multiple type ascriptions on
2594 /// the path from the root of the pattern down to the binding itself.
2598 /// ```ignore (illustrative)
2599 /// struct S<'a>((i32, &'a str), String);
2600 /// let S((_, w): (i32, &'static str), _): S = ...;
2601 /// // ------ ^^^^^^^^^^^^^^^^^^^ (1)
2602 /// // --------------------------------- ^ (2)
2605 /// The highlights labelled `(1)` show the subpattern `(_, w)` being
2606 /// ascribed the type `(i32, &'static str)`.
2608 /// The highlights labelled `(2)` show the whole pattern being
2609 /// ascribed the type `S`.
2611 /// In this example, when we descend to `w`, we will have built up the
2612 /// following two projected types:
2614 /// * base: `S`, projection: `(base.0).1`
2615 /// * base: `(i32, &'static str)`, projection: `base.1`
2617 /// The first will lead to the constraint `w: &'1 str` (for some
2618 /// inferred region `'1`). The second will lead to the constraint `w:
2620 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
2621 pub struct UserTypeProjections {
2622 pub contents: Vec<(UserTypeProjection, Span)>,
2625 impl<'tcx> UserTypeProjections {
2626 pub fn none() -> Self {
2627 UserTypeProjections { contents: vec![] }
2630 pub fn is_empty(&self) -> bool {
2631 self.contents.is_empty()
2634 pub fn projections_and_spans(
2636 ) -> impl Iterator<Item = &(UserTypeProjection, Span)> + ExactSizeIterator {
2637 self.contents.iter()
2640 pub fn projections(&self) -> impl Iterator<Item = &UserTypeProjection> + ExactSizeIterator {
2641 self.contents.iter().map(|&(ref user_type, _span)| user_type)
2644 pub fn push_projection(mut self, user_ty: &UserTypeProjection, span: Span) -> Self {
2645 self.contents.push((user_ty.clone(), span));
2651 mut f: impl FnMut(UserTypeProjection) -> UserTypeProjection,
2653 self.contents = self.contents.into_iter().map(|(proj, span)| (f(proj), span)).collect();
2657 pub fn index(self) -> Self {
2658 self.map_projections(|pat_ty_proj| pat_ty_proj.index())
2661 pub fn subslice(self, from: u64, to: u64) -> Self {
2662 self.map_projections(|pat_ty_proj| pat_ty_proj.subslice(from, to))
2665 pub fn deref(self) -> Self {
2666 self.map_projections(|pat_ty_proj| pat_ty_proj.deref())
2669 pub fn leaf(self, field: Field) -> Self {
2670 self.map_projections(|pat_ty_proj| pat_ty_proj.leaf(field))
2673 pub fn variant(self, adt_def: AdtDef<'tcx>, variant_index: VariantIdx, field: Field) -> Self {
2674 self.map_projections(|pat_ty_proj| pat_ty_proj.variant(adt_def, variant_index, field))
2678 /// Encodes the effect of a user-supplied type annotation on the
2679 /// subcomponents of a pattern. The effect is determined by applying the
2680 /// given list of projections to some underlying base type. Often,
2681 /// the projection element list `projs` is empty, in which case this
2682 /// directly encodes a type in `base`. But in the case of complex patterns with
2683 /// subpatterns and bindings, we want to apply only a *part* of the type to a variable,
2684 /// in which case the `projs` vector is used.
2688 /// * `let x: T = ...` -- here, the `projs` vector is empty.
2690 /// * `let (x, _): T = ...` -- here, the `projs` vector would contain
2691 /// `field[0]` (aka `.0`), indicating that the type of `s` is
2692 /// determined by finding the type of the `.0` field from `T`.
2693 #[derive(Clone, Debug, TyEncodable, TyDecodable, Hash, HashStable, PartialEq)]
2694 pub struct UserTypeProjection {
2695 pub base: UserTypeAnnotationIndex,
2696 pub projs: Vec<ProjectionKind>,
2699 impl Copy for ProjectionKind {}
2701 impl UserTypeProjection {
2702 pub(crate) fn index(mut self) -> Self {
2703 self.projs.push(ProjectionElem::Index(()));
2707 pub(crate) fn subslice(mut self, from: u64, to: u64) -> Self {
2708 self.projs.push(ProjectionElem::Subslice { from, to, from_end: true });
2712 pub(crate) fn deref(mut self) -> Self {
2713 self.projs.push(ProjectionElem::Deref);
2717 pub(crate) fn leaf(mut self, field: Field) -> Self {
2718 self.projs.push(ProjectionElem::Field(field, ()));
2722 pub(crate) fn variant(
2724 adt_def: AdtDef<'_>,
2725 variant_index: VariantIdx,
2728 self.projs.push(ProjectionElem::Downcast(
2729 Some(adt_def.variant(variant_index).name),
2732 self.projs.push(ProjectionElem::Field(field, ()));
2737 impl<'tcx> TypeFoldable<'tcx> for UserTypeProjection {
2738 fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
2739 Ok(UserTypeProjection {
2740 base: self.base.try_fold_with(folder)?,
2741 projs: self.projs.try_fold_with(folder)?,
2746 impl<'tcx> TypeVisitable<'tcx> for UserTypeProjection {
2747 fn visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> ControlFlow<Vs::BreakTy> {
2748 self.base.visit_with(visitor)
2749 // Note: there's nothing in `self.proj` to visit.
2753 rustc_index::newtype_index! {
2754 pub struct Promoted {
2756 DEBUG_FORMAT = "promoted[{}]"
2760 impl<'tcx> Debug for Constant<'tcx> {
2761 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2762 write!(fmt, "{}", self)
2766 impl<'tcx> Display for Constant<'tcx> {
2767 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2768 match self.ty().kind() {
2770 _ => write!(fmt, "const ")?,
2772 Display::fmt(&self.literal, fmt)
2776 impl<'tcx> Display for ConstantKind<'tcx> {
2777 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2779 ConstantKind::Ty(c) => pretty_print_const(c, fmt, true),
2780 ConstantKind::Val(val, ty) => pretty_print_const_value(val, ty, fmt, true),
2781 // FIXME(valtrees): Correctly print mir constants.
2782 ConstantKind::Unevaluated(..) => {
2783 fmt.write_str("_")?;
2790 fn pretty_print_const<'tcx>(
2792 fmt: &mut Formatter<'_>,
2795 use crate::ty::print::PrettyPrinter;
2796 ty::tls::with(|tcx| {
2797 let literal = tcx.lift(c).unwrap();
2798 let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
2799 cx.print_alloc_ids = true;
2800 let cx = cx.pretty_print_const(literal, print_types)?;
2801 fmt.write_str(&cx.into_buffer())?;
2806 fn pretty_print_byte_str(fmt: &mut Formatter<'_>, byte_str: &[u8]) -> fmt::Result {
2807 write!(fmt, "b\"{}\"", byte_str.escape_ascii())
2810 fn comma_sep<'tcx>(fmt: &mut Formatter<'_>, elems: Vec<ConstantKind<'tcx>>) -> fmt::Result {
2811 let mut first = true;
2814 fmt.write_str(", ")?;
2816 fmt.write_str(&format!("{}", elem))?;
2822 // FIXME: Move that into `mir/pretty.rs`.
2823 fn pretty_print_const_value<'tcx>(
2824 ct: ConstValue<'tcx>,
2826 fmt: &mut Formatter<'_>,
2829 use crate::ty::print::PrettyPrinter;
2831 ty::tls::with(|tcx| {
2832 let ct = tcx.lift(ct).unwrap();
2833 let ty = tcx.lift(ty).unwrap();
2835 if tcx.sess.verbose() {
2836 fmt.write_str(&format!("ConstValue({:?}: {})", ct, ty))?;
2840 let u8_type = tcx.types.u8;
2841 match (ct, ty.kind()) {
2842 // Byte/string slices, printed as (byte) string literals.
2843 (ConstValue::Slice { data, start, end }, ty::Ref(_, inner, _)) => {
2844 match inner.kind() {
2847 // The `inspect` here is okay since we checked the bounds, and `u8` carries
2848 // no provenance (we have an active slice reference here). We don't use
2849 // this result to affect interpreter execution.
2852 .inspect_with_uninit_and_ptr_outside_interpreter(start..end);
2853 pretty_print_byte_str(fmt, byte_str)?;
2858 // The `inspect` here is okay since we checked the bounds, and `str` carries
2859 // no provenance (we have an active `str` reference here). We don't use this
2860 // result to affect interpreter execution.
2863 .inspect_with_uninit_and_ptr_outside_interpreter(start..end);
2864 fmt.write_str(&format!("{:?}", String::from_utf8_lossy(slice)))?;
2870 (ConstValue::ByRef { alloc, offset }, ty::Array(t, n)) if *t == u8_type => {
2871 let n = n.kind().try_to_bits(tcx.data_layout.pointer_size).unwrap();
2872 // cast is ok because we already checked for pointer size (32 or 64 bit) above
2873 let range = AllocRange { start: offset, size: Size::from_bytes(n) };
2874 let byte_str = alloc.inner().get_bytes_strip_provenance(&tcx, range).unwrap();
2875 fmt.write_str("*")?;
2876 pretty_print_byte_str(fmt, byte_str)?;
2879 // Aggregates, printed as array/tuple/struct/variant construction syntax.
2881 // NB: the `has_non_region_param` check ensures that we can use
2882 // the `destructure_const` query with an empty `ty::ParamEnv` without
2883 // introducing ICEs (e.g. via `layout_of`) from missing bounds.
2884 // E.g. `transmute([0usize; 2]): (u8, *mut T)` needs to know `T: Sized`
2885 // to be able to destructure the tuple into `(0u8, *mut T)
2887 // FIXME(eddyb) for `--emit=mir`/`-Z dump-mir`, we should provide the
2888 // correct `ty::ParamEnv` to allow printing *all* constant values.
2889 (_, ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) if !ty.has_non_region_param() => {
2890 let ct = tcx.lift(ct).unwrap();
2891 let ty = tcx.lift(ty).unwrap();
2892 if let Some(contents) = tcx.try_destructure_mir_constant(
2893 ty::ParamEnv::reveal_all().and(ConstantKind::Val(ct, ty)),
2895 let fields = contents.fields.iter().copied().collect::<Vec<_>>();
2898 fmt.write_str("[")?;
2899 comma_sep(fmt, fields)?;
2900 fmt.write_str("]")?;
2903 fmt.write_str("(")?;
2904 comma_sep(fmt, fields)?;
2905 if contents.fields.len() == 1 {
2906 fmt.write_str(",")?;
2908 fmt.write_str(")")?;
2910 ty::Adt(def, _) if def.variants().is_empty() => {
2911 fmt.write_str(&format!("{{unreachable(): {}}}", ty))?;
2913 ty::Adt(def, substs) => {
2914 let variant_idx = contents
2916 .expect("destructed mir constant of adt without variant idx");
2917 let variant_def = &def.variant(variant_idx);
2918 let substs = tcx.lift(substs).unwrap();
2919 let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
2920 cx.print_alloc_ids = true;
2921 let cx = cx.print_value_path(variant_def.def_id, substs)?;
2922 fmt.write_str(&cx.into_buffer())?;
2924 match variant_def.ctor_kind() {
2925 Some(CtorKind::Const) => {}
2926 Some(CtorKind::Fn) => {
2927 fmt.write_str("(")?;
2928 comma_sep(fmt, fields)?;
2929 fmt.write_str(")")?;
2932 fmt.write_str(" {{ ")?;
2933 let mut first = true;
2934 for (field_def, field) in iter::zip(&variant_def.fields, fields)
2937 fmt.write_str(", ")?;
2939 fmt.write_str(&format!("{}: {}", field_def.name, field))?;
2942 fmt.write_str(" }}")?;
2946 _ => unreachable!(),
2950 // Fall back to debug pretty printing for invalid constants.
2951 fmt.write_str(&format!("{:?}", ct))?;
2953 fmt.write_str(&format!(": {}", ty))?;
2958 (ConstValue::Scalar(scalar), _) => {
2959 let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
2960 cx.print_alloc_ids = true;
2961 let ty = tcx.lift(ty).unwrap();
2962 cx = cx.pretty_print_const_scalar(scalar, ty, print_ty)?;
2963 fmt.write_str(&cx.into_buffer())?;
2966 (ConstValue::ZeroSized, ty::FnDef(d, s)) => {
2967 let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
2968 cx.print_alloc_ids = true;
2969 let cx = cx.print_value_path(*d, s)?;
2970 fmt.write_str(&cx.into_buffer())?;
2973 // FIXME(oli-obk): also pretty print arrays and other aggregate constants by reading
2974 // their fields instead of just dumping the memory.
2978 fmt.write_str(&format!("{:?}", ct))?;
2980 fmt.write_str(&format!(": {}", ty))?;
2986 /// `Location` represents the position of the start of the statement; or, if
2987 /// `statement_index` equals the number of statements, then the start of the
2989 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd, HashStable)]
2990 pub struct Location {
2991 /// The block that the location is within.
2992 pub block: BasicBlock,
2994 pub statement_index: usize,
2997 impl fmt::Debug for Location {
2998 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2999 write!(fmt, "{:?}[{}]", self.block, self.statement_index)
3004 pub const START: Location = Location { block: START_BLOCK, statement_index: 0 };
3006 /// Returns the location immediately after this one within the enclosing block.
3008 /// Note that if this location represents a terminator, then the
3009 /// resulting location would be out of bounds and invalid.
3010 pub fn successor_within_block(&self) -> Location {
3011 Location { block: self.block, statement_index: self.statement_index + 1 }
3014 /// Returns `true` if `other` is earlier in the control flow graph than `self`.
3015 pub fn is_predecessor_of<'tcx>(&self, other: Location, body: &Body<'tcx>) -> bool {
3016 // If we are in the same block as the other location and are an earlier statement
3017 // then we are a predecessor of `other`.
3018 if self.block == other.block && self.statement_index < other.statement_index {
3022 let predecessors = body.basic_blocks.predecessors();
3024 // If we're in another block, then we want to check that block is a predecessor of `other`.
3025 let mut queue: Vec<BasicBlock> = predecessors[other.block].to_vec();
3026 let mut visited = FxHashSet::default();
3028 while let Some(block) = queue.pop() {
3029 // If we haven't visited this block before, then make sure we visit its predecessors.
3030 if visited.insert(block) {
3031 queue.extend(predecessors[block].iter().cloned());
3036 // If we found the block that `self` is in, then we are a predecessor of `other` (since
3037 // we found that block by looking at the predecessors of `other`).
3038 if self.block == block {
3046 pub fn dominates(&self, other: Location, dominators: &Dominators<BasicBlock>) -> bool {
3047 if self.block == other.block {
3048 self.statement_index <= other.statement_index
3050 dominators.is_dominated_by(other.block, self.block)
3055 // Some nodes are used a lot. Make sure they don't unintentionally get bigger.
3056 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
3059 use rustc_data_structures::static_assert_size;
3060 // tidy-alphabetical-start
3061 static_assert_size!(BasicBlockData<'_>, 144);
3062 static_assert_size!(LocalDecl<'_>, 56);
3063 static_assert_size!(Statement<'_>, 32);
3064 static_assert_size!(StatementKind<'_>, 16);
3065 static_assert_size!(Terminator<'_>, 112);
3066 static_assert_size!(TerminatorKind<'_>, 96);
3067 // tidy-alphabetical-end