1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! MIR datatypes and passes. See the [rustc guide] for more info.
13 //! [rustc guide]: https://rust-lang-nursery.github.io/rustc-guide/mir/index.html
15 use graphviz::IntoCow;
16 use hir::def::CtorKind;
17 use hir::def_id::DefId;
18 use hir::{self, HirId, InlineAsm};
20 use mir::interpret::{ConstValue, EvalErrorKind, Scalar};
21 use mir::visit::MirVisitable;
22 use rustc_apfloat::ieee::{Double, Single};
23 use rustc_apfloat::Float;
24 use rustc_data_structures::graph::dominators::{dominators, Dominators};
25 use rustc_data_structures::graph::{self, GraphPredecessors, GraphSuccessors};
26 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
27 use rustc_data_structures::sync::Lrc;
28 use rustc_data_structures::sync::MappedReadGuard;
29 use rustc_serialize as serialize;
30 use smallvec::SmallVec;
32 use std::fmt::{self, Debug, Formatter, Write};
33 use std::ops::{Index, IndexMut};
35 use std::vec::IntoIter;
36 use std::{iter, mem, option, u32};
37 use syntax::ast::{self, Name};
38 use syntax::symbol::InternedString;
39 use syntax_pos::{Span, DUMMY_SP};
40 use ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
41 use ty::subst::{Subst, Substs};
42 use ty::{self, AdtDef, CanonicalTy, ClosureSubsts, GeneratorSubsts, Region, Ty, TyCtxt};
45 pub use mir::interpret::AssertMessage;
55 type LocalDecls<'tcx> = IndexVec<Local, LocalDecl<'tcx>>;
57 pub trait HasLocalDecls<'tcx> {
58 fn local_decls(&self) -> &LocalDecls<'tcx>;
61 impl<'tcx> HasLocalDecls<'tcx> for LocalDecls<'tcx> {
62 fn local_decls(&self) -> &LocalDecls<'tcx> {
67 impl<'tcx> HasLocalDecls<'tcx> for Mir<'tcx> {
68 fn local_decls(&self) -> &LocalDecls<'tcx> {
73 /// Lowered representation of a single function.
74 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
75 pub struct Mir<'tcx> {
76 /// List of basic blocks. References to basic block use a newtyped index type `BasicBlock`
77 /// that indexes into this vector.
78 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
80 /// List of source scopes; these are referenced by statements
81 /// and used for debuginfo. Indexed by a `SourceScope`.
82 pub source_scopes: IndexVec<SourceScope, SourceScopeData>,
84 /// Crate-local information for each source scope, that can't (and
85 /// needn't) be tracked across crates.
86 pub source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
88 /// Rvalues promoted from this function, such as borrows of constants.
89 /// Each of them is the Mir of a constant with the fn's type parameters
90 /// in scope, but a separate set of locals.
91 pub promoted: IndexVec<Promoted, Mir<'tcx>>,
93 /// Yield type of the function, if it is a generator.
94 pub yield_ty: Option<Ty<'tcx>>,
96 /// Generator drop glue
97 pub generator_drop: Option<Box<Mir<'tcx>>>,
99 /// The layout of a generator. Produced by the state transformation.
100 pub generator_layout: Option<GeneratorLayout<'tcx>>,
102 /// Declarations of locals.
104 /// The first local is the return value pointer, followed by `arg_count`
105 /// locals for the function arguments, followed by any user-declared
106 /// variables and temporaries.
107 pub local_decls: LocalDecls<'tcx>,
109 /// Number of arguments this function takes.
111 /// Starting at local 1, `arg_count` locals will be provided by the caller
112 /// and can be assumed to be initialized.
114 /// If this MIR was built for a constant, this will be 0.
115 pub arg_count: usize,
117 /// Names and capture modes of all the closure upvars, assuming
118 /// the first argument is either the closure or a reference to it.
119 pub upvar_decls: Vec<UpvarDecl>,
121 /// Mark an argument local (which must be a tuple) as getting passed as
122 /// its individual components at the LLVM level.
124 /// This is used for the "rust-call" ABI.
125 pub spread_arg: Option<Local>,
127 /// A span representing this MIR, for error reporting
130 /// A cache for various calculations
134 impl<'tcx> Mir<'tcx> {
136 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
137 source_scopes: IndexVec<SourceScope, SourceScopeData>,
138 source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
139 promoted: IndexVec<Promoted, Mir<'tcx>>,
140 yield_ty: Option<Ty<'tcx>>,
141 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
143 upvar_decls: Vec<UpvarDecl>,
146 // We need `arg_count` locals, and one for the return place
148 local_decls.len() >= arg_count + 1,
149 "expected at least {} locals, got {}",
157 source_scope_local_data,
160 generator_drop: None,
161 generator_layout: None,
167 cache: cache::Cache::new(),
172 pub fn basic_blocks(&self) -> &IndexVec<BasicBlock, BasicBlockData<'tcx>> {
177 pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
178 self.cache.invalidate();
179 &mut self.basic_blocks
183 pub fn basic_blocks_and_local_decls_mut(
186 &mut IndexVec<BasicBlock, BasicBlockData<'tcx>>,
187 &mut LocalDecls<'tcx>,
189 self.cache.invalidate();
190 (&mut self.basic_blocks, &mut self.local_decls)
194 pub fn predecessors(&self) -> MappedReadGuard<'_, IndexVec<BasicBlock, Vec<BasicBlock>>> {
195 self.cache.predecessors(self)
199 pub fn predecessors_for(&self, bb: BasicBlock) -> MappedReadGuard<'_, Vec<BasicBlock>> {
200 MappedReadGuard::map(self.predecessors(), |p| &p[bb])
204 pub fn predecessor_locations(&self, loc: Location) -> impl Iterator<Item = Location> + '_ {
205 let if_zero_locations = if loc.statement_index == 0 {
206 let predecessor_blocks = self.predecessors_for(loc.block);
207 let num_predecessor_blocks = predecessor_blocks.len();
209 (0..num_predecessor_blocks)
210 .map(move |i| predecessor_blocks[i])
211 .map(move |bb| self.terminator_loc(bb)),
217 let if_not_zero_locations = if loc.statement_index == 0 {
222 statement_index: loc.statement_index - 1,
229 .chain(if_not_zero_locations)
233 pub fn dominators(&self) -> Dominators<BasicBlock> {
238 pub fn local_kind(&self, local: Local) -> LocalKind {
239 let index = local.as_usize();
242 self.local_decls[local].mutability == Mutability::Mut,
243 "return place should be mutable"
246 LocalKind::ReturnPointer
247 } else if index < self.arg_count + 1 {
249 } else if self.local_decls[local].name.is_some() {
256 /// Returns an iterator over all temporaries.
258 pub fn temps_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
259 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
260 let local = Local::new(index);
261 if self.local_decls[local].is_user_variable.is_some() {
269 /// Returns an iterator over all user-declared locals.
271 pub fn vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
272 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
273 let local = Local::new(index);
274 if self.local_decls[local].is_user_variable.is_some() {
282 /// Returns an iterator over all user-declared mutable arguments and locals.
284 pub fn mut_vars_and_args_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
285 (1..self.local_decls.len()).filter_map(move |index| {
286 let local = Local::new(index);
287 let decl = &self.local_decls[local];
288 if (decl.is_user_variable.is_some() || index < self.arg_count + 1)
289 && decl.mutability == Mutability::Mut
298 /// Returns an iterator over all function arguments.
300 pub fn args_iter(&self) -> impl Iterator<Item = Local> {
301 let arg_count = self.arg_count;
302 (1..arg_count + 1).map(Local::new)
305 /// Returns an iterator over all user-defined variables and compiler-generated temporaries (all
306 /// locals that are neither arguments nor the return place).
308 pub fn vars_and_temps_iter(&self) -> impl Iterator<Item = Local> {
309 let arg_count = self.arg_count;
310 let local_count = self.local_decls.len();
311 (arg_count + 1..local_count).map(Local::new)
314 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
315 /// invalidating statement indices in `Location`s.
316 pub fn make_statement_nop(&mut self, location: Location) {
317 let block = &mut self[location.block];
318 debug_assert!(location.statement_index < block.statements.len());
319 block.statements[location.statement_index].make_nop()
322 /// Returns the source info associated with `location`.
323 pub fn source_info(&self, location: Location) -> &SourceInfo {
324 let block = &self[location.block];
325 let stmts = &block.statements;
326 let idx = location.statement_index;
327 if idx < stmts.len() {
328 &stmts[idx].source_info
330 assert!(idx == stmts.len());
331 &block.terminator().source_info
335 /// Check if `sub` is a sub scope of `sup`
336 pub fn is_sub_scope(&self, mut sub: SourceScope, sup: SourceScope) -> bool {
341 match self.source_scopes[sub].parent_scope {
342 None => return false,
348 /// Return the return type, it always return first element from `local_decls` array
349 pub fn return_ty(&self) -> Ty<'tcx> {
350 self.local_decls[RETURN_PLACE].ty
353 /// Get the location of the terminator for the given block
354 pub fn terminator_loc(&self, bb: BasicBlock) -> Location {
357 statement_index: self[bb].statements.len(),
362 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
365 /// Unsafe because of a PushUnsafeBlock
367 /// Unsafe because of an unsafe fn
369 /// Unsafe because of an `unsafe` block
370 ExplicitUnsafe(ast::NodeId),
373 impl_stable_hash_for!(struct Mir<'tcx> {
376 source_scope_local_data,
389 impl<'tcx> Index<BasicBlock> for Mir<'tcx> {
390 type Output = BasicBlockData<'tcx>;
393 fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
394 &self.basic_blocks()[index]
398 impl<'tcx> IndexMut<BasicBlock> for Mir<'tcx> {
400 fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> {
401 &mut self.basic_blocks_mut()[index]
405 #[derive(Copy, Clone, Debug)]
406 pub enum ClearCrossCrate<T> {
411 impl<T> ClearCrossCrate<T> {
412 pub fn assert_crate_local(self) -> T {
414 ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"),
415 ClearCrossCrate::Set(v) => v,
420 impl<T: serialize::Encodable> serialize::UseSpecializedEncodable for ClearCrossCrate<T> {}
421 impl<T: serialize::Decodable> serialize::UseSpecializedDecodable for ClearCrossCrate<T> {}
423 /// Grouped information about the source code origin of a MIR entity.
424 /// Intended to be inspected by diagnostics and debuginfo.
425 /// Most passes can work with it as a whole, within a single function.
426 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
427 pub struct SourceInfo {
428 /// Source span for the AST pertaining to this MIR entity.
431 /// The source scope, keeping track of which bindings can be
432 /// seen by debuginfo, active lint levels, `unsafe {...}`, etc.
433 pub scope: SourceScope,
436 ///////////////////////////////////////////////////////////////////////////
437 // Mutability and borrow kinds
439 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
440 pub enum Mutability {
445 impl From<Mutability> for hir::Mutability {
446 fn from(m: Mutability) -> Self {
448 Mutability::Mut => hir::MutMutable,
449 Mutability::Not => hir::MutImmutable,
454 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable)]
455 pub enum BorrowKind {
456 /// Data must be immutable and is aliasable.
459 /// The immediately borrowed place must be immutable, but projections from
460 /// it don't need to be. For example, a shallow borrow of `a.b` doesn't
461 /// conflict with a mutable borrow of `a.b.c`.
463 /// This is used when lowering matches: when matching on a place we want to
464 /// ensure that place have the same value from the start of the match until
465 /// an arm is selected. This prevents this code from compiling:
467 /// let mut x = &Some(0);
470 /// Some(_) if { x = &None; false } => (),
474 /// This can't be a shared borrow because mutably borrowing (*x as Some).0
475 /// should not prevent `if let None = x { ... }`, for example, becase the
476 /// mutating `(*x as Some).0` can't affect the discriminant of `x`.
477 /// We can also report errors with this kind of borrow differently.
480 /// Data must be immutable but not aliasable. This kind of borrow
481 /// cannot currently be expressed by the user and is used only in
482 /// implicit closure bindings. It is needed when the closure is
483 /// borrowing or mutating a mutable referent, e.g.:
485 /// let x: &mut isize = ...;
486 /// let y = || *x += 5;
488 /// If we were to try to translate this closure into a more explicit
489 /// form, we'd encounter an error with the code as written:
491 /// struct Env { x: & &mut isize }
492 /// let x: &mut isize = ...;
493 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
494 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
496 /// This is then illegal because you cannot mutate an `&mut` found
497 /// in an aliasable location. To solve, you'd have to translate with
498 /// an `&mut` borrow:
500 /// struct Env { x: & &mut isize }
501 /// let x: &mut isize = ...;
502 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
503 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
505 /// Now the assignment to `**env.x` is legal, but creating a
506 /// mutable pointer to `x` is not because `x` is not mutable. We
507 /// could fix this by declaring `x` as `let mut x`. This is ok in
508 /// user code, if awkward, but extra weird for closures, since the
509 /// borrow is hidden.
511 /// So we introduce a "unique imm" borrow -- the referent is
512 /// immutable, but not aliasable. This solves the problem. For
513 /// simplicity, we don't give users the way to express this
514 /// borrow, it's just used when translating closures.
517 /// Data is mutable and not aliasable.
519 /// True if this borrow arose from method-call auto-ref
520 /// (i.e. `adjustment::Adjust::Borrow`)
521 allow_two_phase_borrow: bool,
526 pub fn allows_two_phase_borrow(&self) -> bool {
528 BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => false,
530 allow_two_phase_borrow,
531 } => allow_two_phase_borrow,
536 ///////////////////////////////////////////////////////////////////////////
537 // Variables and temps
541 DEBUG_FORMAT = "_{}",
542 const RETURN_PLACE = 0,
546 /// Classifies locals into categories. See `Mir::local_kind`.
547 #[derive(PartialEq, Eq, Debug)]
549 /// User-declared variable binding
551 /// Compiler-introduced temporary
553 /// Function argument
555 /// Location of function's return value
559 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
560 pub struct VarBindingForm<'tcx> {
561 /// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`?
562 pub binding_mode: ty::BindingMode,
563 /// If an explicit type was provided for this variable binding,
564 /// this holds the source Span of that type.
566 /// NOTE: If you want to change this to a `HirId`, be wary that
567 /// doing so breaks incremental compilation (as of this writing),
568 /// while a `Span` does not cause our tests to fail.
569 pub opt_ty_info: Option<Span>,
570 /// Place of the RHS of the =, or the subject of the `match` where this
571 /// variable is initialized. None in the case of `let PATTERN;`.
572 /// Some((None, ..)) in the case of and `let [mut] x = ...` because
573 /// (a) the right-hand side isn't evaluated as a place expression.
574 /// (b) it gives a way to separate this case from the remaining cases
576 pub opt_match_place: Option<(Option<Place<'tcx>>, Span)>,
577 /// Span of the pattern in which this variable was bound.
581 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
582 pub enum BindingForm<'tcx> {
583 /// This is a binding for a non-`self` binding, or a `self` that has an explicit type.
584 Var(VarBindingForm<'tcx>),
585 /// Binding for a `self`/`&self`/`&mut self` binding where the type is implicit.
586 ImplicitSelf(ImplicitSelfKind),
587 /// Reference used in a guard expression to ensure immutability.
591 /// Represents what type of implicit self a function has, if any.
592 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
593 pub enum ImplicitSelfKind {
594 /// Represents a `fn x(self);`.
596 /// Represents a `fn x(mut self);`.
598 /// Represents a `fn x(&self);`.
600 /// Represents a `fn x(&mut self);`.
602 /// Represents when a function does not have a self argument or
603 /// when a function has a `self: X` argument.
607 CloneTypeFoldableAndLiftImpls! { BindingForm<'tcx>, }
609 impl_stable_hash_for!(struct self::VarBindingForm<'tcx> {
616 impl_stable_hash_for!(enum self::ImplicitSelfKind {
624 mod binding_form_impl {
625 use ich::StableHashingContext;
626 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableHasherResult};
628 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
629 fn hash_stable<W: StableHasherResult>(
631 hcx: &mut StableHashingContext<'a>,
632 hasher: &mut StableHasher<W>,
634 use super::BindingForm::*;
635 ::std::mem::discriminant(self).hash_stable(hcx, hasher);
638 Var(binding) => binding.hash_stable(hcx, hasher),
639 ImplicitSelf(kind) => kind.hash_stable(hcx, hasher),
648 /// This can be a binding declared by the user, a temporary inserted by the compiler, a function
649 /// argument, or the return place.
650 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
651 pub struct LocalDecl<'tcx> {
652 /// `let mut x` vs `let x`.
654 /// Temporaries and the return place are always mutable.
655 pub mutability: Mutability,
657 /// Some(binding_mode) if this corresponds to a user-declared local variable.
659 /// This is solely used for local diagnostics when generating
660 /// warnings/errors when compiling the current crate, and
661 /// therefore it need not be visible across crates. pnkfelix
662 /// currently hypothesized we *need* to wrap this in a
663 /// `ClearCrossCrate` as long as it carries as `HirId`.
664 pub is_user_variable: Option<ClearCrossCrate<BindingForm<'tcx>>>,
666 /// True if this is an internal local
668 /// These locals are not based on types in the source code and are only used
669 /// for a few desugarings at the moment.
671 /// The generator transformation will sanity check the locals which are live
672 /// across a suspension point against the type components of the generator
673 /// which type checking knows are live across a suspension point. We need to
674 /// flag drop flags to avoid triggering this check as they are introduced
677 /// Unsafety checking will also ignore dereferences of these locals,
678 /// so they can be used for raw pointers only used in a desugaring.
680 /// This should be sound because the drop flags are fully algebraic, and
681 /// therefore don't affect the OIBIT or outlives properties of the
685 /// Type of this local.
688 /// If the user manually ascribed a type to this variable,
689 /// e.g. via `let x: T`, then we carry that type here. The MIR
690 /// borrow checker needs this information since it can affect
691 /// region inference.
692 pub user_ty: Option<CanonicalTy<'tcx>>,
694 /// Name of the local, used in debuginfo and pretty-printing.
696 /// Note that function arguments can also have this set to `Some(_)`
697 /// to generate better debuginfo.
698 pub name: Option<Name>,
700 /// The *syntactic* (i.e. not visibility) source scope the local is defined
701 /// in. If the local was defined in a let-statement, this
702 /// is *within* the let-statement, rather than outside
705 /// This is needed because the visibility source scope of locals within
706 /// a let-statement is weird.
708 /// The reason is that we want the local to be *within* the let-statement
709 /// for lint purposes, but we want the local to be *after* the let-statement
710 /// for names-in-scope purposes.
712 /// That's it, if we have a let-statement like the one in this
716 /// fn foo(x: &str) {
717 /// #[allow(unused_mut)]
718 /// let mut x: u32 = { // <- one unused mut
719 /// let mut y: u32 = x.parse().unwrap();
726 /// Then, from a lint point of view, the declaration of `x: u32`
727 /// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the
728 /// lint scopes are the same as the AST/HIR nesting.
730 /// However, from a name lookup point of view, the scopes look more like
731 /// as if the let-statements were `match` expressions:
734 /// fn foo(x: &str) {
736 /// match x.parse().unwrap() {
745 /// We care about the name-lookup scopes for debuginfo - if the
746 /// debuginfo instruction pointer is at the call to `x.parse()`, we
747 /// want `x` to refer to `x: &str`, but if it is at the call to
748 /// `drop(x)`, we want it to refer to `x: u32`.
750 /// To allow both uses to work, we need to have more than a single scope
751 /// for a local. We have the `source_info.scope` represent the
752 /// "syntactic" lint scope (with a variable being under its let
753 /// block) while the `visibility_scope` represents the "local variable"
754 /// scope (where the "rest" of a block is under all prior let-statements).
756 /// The end result looks like this:
760 /// │{ argument x: &str }
762 /// │ │{ #[allow(unused_mut)] } // this is actually split into 2 scopes
763 /// │ │ // in practice because I'm lazy.
765 /// │ │← x.source_info.scope
766 /// │ │← `x.parse().unwrap()`
768 /// │ │ │← y.source_info.scope
770 /// │ │ │{ let y: u32 }
772 /// │ │ │← y.visibility_scope
775 /// │ │{ let x: u32 }
776 /// │ │← x.visibility_scope
777 /// │ │← `drop(x)` // this accesses `x: u32`
779 pub source_info: SourceInfo,
781 /// Source scope within which the local is visible (for debuginfo)
782 /// (see `source_info` for more details).
783 pub visibility_scope: SourceScope,
786 impl<'tcx> LocalDecl<'tcx> {
787 /// Returns true only if local is a binding that can itself be
788 /// made mutable via the addition of the `mut` keyword, namely
789 /// something like the occurrences of `x` in:
790 /// - `fn foo(x: Type) { ... }`,
792 /// - or `match ... { C(x) => ... }`
793 pub fn can_be_made_mutable(&self) -> bool {
794 match self.is_user_variable {
795 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
796 binding_mode: ty::BindingMode::BindByValue(_),
802 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf(ImplicitSelfKind::Imm)))
809 /// Returns true if local is definitely not a `ref ident` or
810 /// `ref mut ident` binding. (Such bindings cannot be made into
811 /// mutable bindings, but the inverse does not necessarily hold).
812 pub fn is_nonref_binding(&self) -> bool {
813 match self.is_user_variable {
814 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
815 binding_mode: ty::BindingMode::BindByValue(_),
821 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf(_))) => true,
827 /// Create a new `LocalDecl` for a temporary.
829 pub fn new_temp(ty: Ty<'tcx>, span: Span) -> Self {
830 Self::new_local(ty, Mutability::Mut, false, span)
833 /// Create a new immutable `LocalDecl` for a temporary.
835 pub fn new_immutable_temp(ty: Ty<'tcx>, span: Span) -> Self {
836 Self::new_local(ty, Mutability::Not, false, span)
839 /// Create a new `LocalDecl` for a internal temporary.
841 pub fn new_internal(ty: Ty<'tcx>, span: Span) -> Self {
842 Self::new_local(ty, Mutability::Mut, true, span)
848 mutability: Mutability,
857 source_info: SourceInfo {
859 scope: OUTERMOST_SOURCE_SCOPE,
861 visibility_scope: OUTERMOST_SOURCE_SCOPE,
863 is_user_variable: None,
867 /// Builds a `LocalDecl` for the return place.
869 /// This must be inserted into the `local_decls` list as the first local.
871 pub fn new_return_place(return_ty: Ty<'_>, span: Span) -> LocalDecl<'_> {
873 mutability: Mutability::Mut,
876 source_info: SourceInfo {
878 scope: OUTERMOST_SOURCE_SCOPE,
880 visibility_scope: OUTERMOST_SOURCE_SCOPE,
882 name: None, // FIXME maybe we do want some name here?
883 is_user_variable: None,
888 /// A closure capture, with its name and mode.
889 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
890 pub struct UpvarDecl {
891 pub debug_name: Name,
893 /// `HirId` of the captured variable
894 pub var_hir_id: ClearCrossCrate<HirId>,
896 /// If true, the capture is behind a reference.
899 pub mutability: Mutability,
902 ///////////////////////////////////////////////////////////////////////////
906 pub struct BasicBlock {
907 DEBUG_FORMAT = "bb{}",
908 const START_BLOCK = 0,
913 pub fn start_location(self) -> Location {
921 ///////////////////////////////////////////////////////////////////////////
922 // BasicBlockData and Terminator
924 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
925 pub struct BasicBlockData<'tcx> {
926 /// List of statements in this block.
927 pub statements: Vec<Statement<'tcx>>,
929 /// Terminator for this block.
931 /// NB. This should generally ONLY be `None` during construction.
932 /// Therefore, you should generally access it via the
933 /// `terminator()` or `terminator_mut()` methods. The only
934 /// exception is that certain passes, such as `simplify_cfg`, swap
935 /// out the terminator temporarily with `None` while they continue
936 /// to recurse over the set of basic blocks.
937 pub terminator: Option<Terminator<'tcx>>,
939 /// If true, this block lies on an unwind path. This is used
940 /// during codegen where distinct kinds of basic blocks may be
941 /// generated (particularly for MSVC cleanup). Unwind blocks must
942 /// only branch to other unwind blocks.
943 pub is_cleanup: bool,
946 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
947 pub struct Terminator<'tcx> {
948 pub source_info: SourceInfo,
949 pub kind: TerminatorKind<'tcx>,
952 #[derive(Clone, RustcEncodable, RustcDecodable)]
953 pub enum TerminatorKind<'tcx> {
954 /// block should have one successor in the graph; we jump there
955 Goto { target: BasicBlock },
957 /// operand evaluates to an integer; jump depending on its value
958 /// to one of the targets, and otherwise fallback to `otherwise`
960 /// discriminant value being tested
961 discr: Operand<'tcx>,
963 /// type of value being tested
966 /// Possible values. The locations to branch to in each case
967 /// are found in the corresponding indices from the `targets` vector.
968 values: Cow<'tcx, [u128]>,
970 /// Possible branch sites. The last element of this vector is used
971 /// for the otherwise branch, so targets.len() == values.len() + 1
973 // This invariant is quite non-obvious and also could be improved.
974 // One way to make this invariant is to have something like this instead:
976 // branches: Vec<(ConstInt, BasicBlock)>,
977 // otherwise: Option<BasicBlock> // exhaustive if None
979 // However we’ve decided to keep this as-is until we figure a case
980 // where some other approach seems to be strictly better than other.
981 targets: Vec<BasicBlock>,
984 /// Indicates that the landing pad is finished and unwinding should
985 /// continue. Emitted by build::scope::diverge_cleanup.
988 /// Indicates that the landing pad is finished and that the process
989 /// should abort. Used to prevent unwinding for foreign items.
992 /// Indicates a normal return. The return place should have
993 /// been filled in by now. This should occur at most once.
996 /// Indicates a terminator that can never be reached.
1001 location: Place<'tcx>,
1003 unwind: Option<BasicBlock>,
1006 /// Drop the Place and assign the new value over it. This ensures
1007 /// that the assignment to `P` occurs *even if* the destructor for
1008 /// place unwinds. Its semantics are best explained by the
1013 /// DropAndReplace(P <- V, goto BB1, unwind BB2)
1021 /// Drop(P, goto BB1, unwind BB2)
1024 /// // P is now uninitialized
1028 /// // P is now uninitialized -- its dtor panicked
1033 location: Place<'tcx>,
1034 value: Operand<'tcx>,
1036 unwind: Option<BasicBlock>,
1039 /// Block ends with a call of a converging function
1041 /// The function that’s being called
1042 func: Operand<'tcx>,
1043 /// Arguments the function is called with.
1044 /// These are owned by the callee, which is free to modify them.
1045 /// This allows the memory occupied by "by-value" arguments to be
1046 /// reused across function calls without duplicating the contents.
1047 args: Vec<Operand<'tcx>>,
1048 /// Destination for the return value. If some, the call is converging.
1049 destination: Option<(Place<'tcx>, BasicBlock)>,
1050 /// Cleanups to be done if the call unwinds.
1051 cleanup: Option<BasicBlock>,
1054 /// Jump to the target if the condition has the expected value,
1055 /// otherwise panic with a message and a cleanup target.
1057 cond: Operand<'tcx>,
1059 msg: AssertMessage<'tcx>,
1061 cleanup: Option<BasicBlock>,
1066 /// The value to return
1067 value: Operand<'tcx>,
1068 /// Where to resume to
1070 /// Cleanup to be done if the generator is dropped at this suspend point
1071 drop: Option<BasicBlock>,
1074 /// Indicates the end of the dropping of a generator
1077 /// A block where control flow only ever takes one real path, but borrowck
1078 /// needs to be more conservative.
1080 /// The target normal control flow will take
1081 real_target: BasicBlock,
1082 /// The list of blocks control flow could conceptually take, but won't
1084 imaginary_targets: Vec<BasicBlock>,
1086 /// A terminator for blocks that only take one path in reality, but where we
1087 /// reserve the right to unwind in borrowck, even if it won't happen in practice.
1088 /// This can arise in infinite loops with no function calls for example.
1090 /// The target normal control flow will take
1091 real_target: BasicBlock,
1092 /// The imaginary cleanup block link. This particular path will never be taken
1093 /// in practice, but in order to avoid fragility we want to always
1094 /// consider it in borrowck. We don't want to accept programs which
1095 /// pass borrowck only when panic=abort or some assertions are disabled
1096 /// due to release vs. debug mode builds. This needs to be an Option because
1097 /// of the remove_noop_landing_pads and no_landing_pads passes
1098 unwind: Option<BasicBlock>,
1102 pub type Successors<'a> =
1103 iter::Chain<option::IntoIter<&'a BasicBlock>, slice::Iter<'a, BasicBlock>>;
1104 pub type SuccessorsMut<'a> =
1105 iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>;
1107 impl<'tcx> Terminator<'tcx> {
1108 pub fn successors(&self) -> Successors<'_> {
1109 self.kind.successors()
1112 pub fn successors_mut(&mut self) -> SuccessorsMut<'_> {
1113 self.kind.successors_mut()
1116 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1120 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1121 self.kind.unwind_mut()
1125 impl<'tcx> TerminatorKind<'tcx> {
1126 pub fn if_<'a, 'gcx>(
1127 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1128 cond: Operand<'tcx>,
1131 ) -> TerminatorKind<'tcx> {
1132 static BOOL_SWITCH_FALSE: &'static [u128] = &[0];
1133 TerminatorKind::SwitchInt {
1135 switch_ty: tcx.types.bool,
1136 values: From::from(BOOL_SWITCH_FALSE),
1137 targets: vec![f, t],
1141 pub fn successors(&self) -> Successors<'_> {
1142 use self::TerminatorKind::*;
1153 } => None.into_iter().chain(&[]),
1154 Goto { target: ref t }
1157 cleanup: Some(ref t),
1161 destination: Some((_, ref t)),
1188 } => Some(t).into_iter().chain(&[]),
1190 destination: Some((_, ref t)),
1191 cleanup: Some(ref u),
1201 unwind: Some(ref u),
1206 unwind: Some(ref u),
1211 cleanup: Some(ref u),
1216 unwind: Some(ref u),
1217 } => Some(t).into_iter().chain(slice::from_ref(u)),
1218 SwitchInt { ref targets, .. } => None.into_iter().chain(&targets[..]),
1221 ref imaginary_targets,
1222 } => Some(real_target).into_iter().chain(&imaginary_targets[..]),
1226 pub fn successors_mut(&mut self) -> SuccessorsMut<'_> {
1227 use self::TerminatorKind::*;
1238 } => None.into_iter().chain(&mut []),
1239 Goto { target: ref mut t }
1242 cleanup: Some(ref mut t),
1246 destination: Some((_, ref mut t)),
1271 real_target: ref mut t,
1273 } => Some(t).into_iter().chain(&mut []),
1275 destination: Some((_, ref mut t)),
1276 cleanup: Some(ref mut u),
1281 drop: Some(ref mut u),
1286 unwind: Some(ref mut u),
1291 unwind: Some(ref mut u),
1296 cleanup: Some(ref mut u),
1300 real_target: ref mut t,
1301 unwind: Some(ref mut u),
1302 } => Some(t).into_iter().chain(slice::from_mut(u)),
1305 } => None.into_iter().chain(&mut targets[..]),
1307 ref mut real_target,
1308 ref mut imaginary_targets,
1309 } => Some(real_target)
1311 .chain(&mut imaginary_targets[..]),
1315 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1317 TerminatorKind::Goto { .. }
1318 | TerminatorKind::Resume
1319 | TerminatorKind::Abort
1320 | TerminatorKind::Return
1321 | TerminatorKind::Unreachable
1322 | TerminatorKind::GeneratorDrop
1323 | TerminatorKind::Yield { .. }
1324 | TerminatorKind::SwitchInt { .. }
1325 | TerminatorKind::FalseEdges { .. } => None,
1326 TerminatorKind::Call {
1327 cleanup: ref unwind,
1330 | TerminatorKind::Assert {
1331 cleanup: ref unwind,
1334 | TerminatorKind::DropAndReplace { ref unwind, .. }
1335 | TerminatorKind::Drop { ref unwind, .. }
1336 | TerminatorKind::FalseUnwind { ref unwind, .. } => Some(unwind),
1340 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1342 TerminatorKind::Goto { .. }
1343 | TerminatorKind::Resume
1344 | TerminatorKind::Abort
1345 | TerminatorKind::Return
1346 | TerminatorKind::Unreachable
1347 | TerminatorKind::GeneratorDrop
1348 | TerminatorKind::Yield { .. }
1349 | TerminatorKind::SwitchInt { .. }
1350 | TerminatorKind::FalseEdges { .. } => None,
1351 TerminatorKind::Call {
1352 cleanup: ref mut unwind,
1355 | TerminatorKind::Assert {
1356 cleanup: ref mut unwind,
1359 | TerminatorKind::DropAndReplace { ref mut unwind, .. }
1360 | TerminatorKind::Drop { ref mut unwind, .. }
1361 | TerminatorKind::FalseUnwind { ref mut unwind, .. } => Some(unwind),
1366 impl<'tcx> BasicBlockData<'tcx> {
1367 pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
1375 /// Accessor for terminator.
1377 /// Terminator may not be None after construction of the basic block is complete. This accessor
1378 /// provides a convenience way to reach the terminator.
1379 pub fn terminator(&self) -> &Terminator<'tcx> {
1380 self.terminator.as_ref().expect("invalid terminator state")
1383 pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
1384 self.terminator.as_mut().expect("invalid terminator state")
1387 pub fn retain_statements<F>(&mut self, mut f: F)
1389 F: FnMut(&mut Statement<'_>) -> bool,
1391 for s in &mut self.statements {
1398 pub fn expand_statements<F, I>(&mut self, mut f: F)
1400 F: FnMut(&mut Statement<'tcx>) -> Option<I>,
1401 I: iter::TrustedLen<Item = Statement<'tcx>>,
1403 // Gather all the iterators we'll need to splice in, and their positions.
1404 let mut splices: Vec<(usize, I)> = vec![];
1405 let mut extra_stmts = 0;
1406 for (i, s) in self.statements.iter_mut().enumerate() {
1407 if let Some(mut new_stmts) = f(s) {
1408 if let Some(first) = new_stmts.next() {
1409 // We can already store the first new statement.
1412 // Save the other statements for optimized splicing.
1413 let remaining = new_stmts.size_hint().0;
1415 splices.push((i + 1 + extra_stmts, new_stmts));
1416 extra_stmts += remaining;
1424 // Splice in the new statements, from the end of the block.
1425 // FIXME(eddyb) This could be more efficient with a "gap buffer"
1426 // where a range of elements ("gap") is left uninitialized, with
1427 // splicing adding new elements to the end of that gap and moving
1428 // existing elements from before the gap to the end of the gap.
1429 // For now, this is safe code, emulating a gap but initializing it.
1430 let mut gap = self.statements.len()..self.statements.len() + extra_stmts;
1431 self.statements.resize(
1434 source_info: SourceInfo {
1436 scope: OUTERMOST_SOURCE_SCOPE,
1438 kind: StatementKind::Nop,
1441 for (splice_start, new_stmts) in splices.into_iter().rev() {
1442 let splice_end = splice_start + new_stmts.size_hint().0;
1443 while gap.end > splice_end {
1446 self.statements.swap(gap.start, gap.end);
1448 self.statements.splice(splice_start..splice_end, new_stmts);
1449 gap.end = splice_start;
1453 pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
1454 if index < self.statements.len() {
1455 &self.statements[index]
1462 impl<'tcx> Debug for TerminatorKind<'tcx> {
1463 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1464 self.fmt_head(fmt)?;
1465 let successor_count = self.successors().count();
1466 let labels = self.fmt_successor_labels();
1467 assert_eq!(successor_count, labels.len());
1469 match successor_count {
1472 1 => write!(fmt, " -> {:?}", self.successors().nth(0).unwrap()),
1475 write!(fmt, " -> [")?;
1476 for (i, target) in self.successors().enumerate() {
1480 write!(fmt, "{}: {:?}", labels[i], target)?;
1488 impl<'tcx> TerminatorKind<'tcx> {
1489 /// Write the "head" part of the terminator; that is, its name and the data it uses to pick the
1490 /// successor basic block, if any. The only information not included is the list of possible
1491 /// successors, which may be rendered differently between the text and the graphviz format.
1492 pub fn fmt_head<W: Write>(&self, fmt: &mut W) -> fmt::Result {
1493 use self::TerminatorKind::*;
1495 Goto { .. } => write!(fmt, "goto"),
1497 discr: ref place, ..
1498 } => write!(fmt, "switchInt({:?})", place),
1499 Return => write!(fmt, "return"),
1500 GeneratorDrop => write!(fmt, "generator_drop"),
1501 Resume => write!(fmt, "resume"),
1502 Abort => write!(fmt, "abort"),
1503 Yield { ref value, .. } => write!(fmt, "_1 = suspend({:?})", value),
1504 Unreachable => write!(fmt, "unreachable"),
1505 Drop { ref location, .. } => write!(fmt, "drop({:?})", location),
1510 } => write!(fmt, "replace({:?} <- {:?})", location, value),
1517 if let Some((ref destination, _)) = *destination {
1518 write!(fmt, "{:?} = ", destination)?;
1520 write!(fmt, "{:?}(", func)?;
1521 for (index, arg) in args.iter().enumerate() {
1525 write!(fmt, "{:?}", arg)?;
1535 write!(fmt, "assert(")?;
1539 write!(fmt, "{:?}, \"{:?}\")", cond, msg)
1541 FalseEdges { .. } => write!(fmt, "falseEdges"),
1542 FalseUnwind { .. } => write!(fmt, "falseUnwind"),
1546 /// Return the list of labels for the edges to the successor basic blocks.
1547 pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> {
1548 use self::TerminatorKind::*;
1550 Return | Resume | Abort | Unreachable | GeneratorDrop => vec![],
1551 Goto { .. } => vec!["".into()],
1557 let size = ty::tls::with(|tcx| {
1558 let param_env = ty::ParamEnv::empty();
1559 let switch_ty = tcx.lift_to_global(&switch_ty).unwrap();
1560 tcx.layout_of(param_env.and(switch_ty)).unwrap().size
1565 let mut s = String::new();
1567 val: ConstValue::Scalar(
1570 size: size.bytes() as u8,
1575 fmt_const_val(&mut s, &c).unwrap();
1577 }).chain(iter::once(String::from("otherwise").into()))
1581 destination: Some(_),
1584 } => vec!["return".into_cow(), "unwind".into_cow()],
1586 destination: Some(_),
1589 } => vec!["return".into_cow()],
1594 } => vec!["unwind".into_cow()],
1600 Yield { drop: Some(_), .. } => vec!["resume".into_cow(), "drop".into_cow()],
1601 Yield { drop: None, .. } => vec!["resume".into_cow()],
1602 DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => {
1603 vec!["return".into_cow()]
1610 } => vec!["return".into_cow(), "unwind".into_cow()],
1611 Assert { cleanup: None, .. } => vec!["".into()],
1612 Assert { .. } => vec!["success".into_cow(), "unwind".into_cow()],
1614 ref imaginary_targets,
1617 let mut l = vec!["real".into()];
1618 l.resize(imaginary_targets.len() + 1, "imaginary".into());
1623 } => vec!["real".into(), "cleanup".into()],
1624 FalseUnwind { unwind: None, .. } => vec!["real".into()],
1629 ///////////////////////////////////////////////////////////////////////////
1632 #[derive(Clone, RustcEncodable, RustcDecodable)]
1633 pub struct Statement<'tcx> {
1634 pub source_info: SourceInfo,
1635 pub kind: StatementKind<'tcx>,
1638 impl<'tcx> Statement<'tcx> {
1639 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
1640 /// invalidating statement indices in `Location`s.
1641 pub fn make_nop(&mut self) {
1642 self.kind = StatementKind::Nop
1645 /// Changes a statement to a nop and returns the original statement.
1646 pub fn replace_nop(&mut self) -> Self {
1648 source_info: self.source_info,
1649 kind: mem::replace(&mut self.kind, StatementKind::Nop),
1654 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1655 pub enum StatementKind<'tcx> {
1656 /// Write the RHS Rvalue to the LHS Place.
1657 Assign(Place<'tcx>, Box<Rvalue<'tcx>>),
1659 /// This represents all the reading that a pattern match may do
1660 /// (e.g. inspecting constants and discriminant values), and the
1661 /// kind of pattern it comes from. This is in order to adapt potential
1662 /// error messages to these specific patterns.
1663 FakeRead(FakeReadCause, Place<'tcx>),
1665 /// Write the discriminant for a variant to the enum Place.
1668 variant_index: usize,
1671 /// Start a live range for the storage of the local.
1674 /// End the current live range for the storage of the local.
1677 /// Execute a piece of inline Assembly.
1679 asm: Box<InlineAsm>,
1680 outputs: Box<[Place<'tcx>]>,
1681 inputs: Box<[Operand<'tcx>]>,
1684 /// Assert the given places to be valid inhabitants of their type. These statements are
1685 /// currently only interpreted by miri and only generated when "-Z mir-emit-validate" is passed.
1686 /// See <https://internals.rust-lang.org/t/types-as-contracts/5562/73> for more details.
1687 Validate(ValidationOp, Vec<ValidationOperand<'tcx, Place<'tcx>>>),
1689 /// Mark one terminating point of a region scope (i.e. static region).
1690 /// (The starting point(s) arise implicitly from borrows.)
1691 EndRegion(region::Scope),
1693 /// Encodes a user's type ascription. These need to be preserved
1694 /// intact so that NLL can respect them. For example:
1698 /// The effect of this annotation is to relate the type `T_y` of the place `y`
1699 /// to the user-given type `T`. The effect depends on the specified variance:
1701 /// - `Covariant` -- requires that `T_y <: T`
1702 /// - `Contravariant` -- requires that `T_y :> T`
1703 /// - `Invariant` -- requires that `T_y == T`
1704 /// - `Bivariant` -- no effect
1705 AscribeUserType(Place<'tcx>, ty::Variance, CanonicalTy<'tcx>),
1707 /// No-op. Useful for deleting instructions without affecting statement indices.
1711 /// The `FakeReadCause` describes the type of pattern why a `FakeRead` statement exists.
1712 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug)]
1713 pub enum FakeReadCause {
1714 /// Inject a fake read of the borrowed input at the start of each arm's
1715 /// pattern testing code.
1717 /// This should ensure that you cannot change the variant for an enum
1718 /// while you are in the midst of matching on it.
1721 /// `let x: !; match x {}` doesn't generate any read of x so we need to
1722 /// generate a read of x to check that it is initialized and safe.
1725 /// Officially, the semantics of
1727 /// `let pattern = <expr>;`
1729 /// is that `<expr>` is evaluated into a temporary and then this temporary is
1730 /// into the pattern.
1732 /// However, if we see the simple pattern `let var = <expr>`, we optimize this to
1733 /// evaluate `<expr>` directly into the variable `var`. This is mostly unobservable,
1734 /// but in some cases it can affect the borrow checker, as in #53695.
1735 /// Therefore, we insert a "fake read" here to ensure that we get
1736 /// appropriate errors.
1740 /// The `ValidationOp` describes what happens with each of the operands of a
1741 /// `Validate` statement.
1742 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, PartialEq, Eq)]
1743 pub enum ValidationOp {
1744 /// Recursively traverse the place following the type and validate that all type
1745 /// invariants are maintained. Furthermore, acquire exclusive/read-only access to the
1746 /// memory reachable from the place.
1748 /// Recursive traverse the *mutable* part of the type and relinquish all exclusive
1751 /// Recursive traverse the *mutable* part of the type and relinquish all exclusive
1752 /// access *until* the given region ends. Then, access will be recovered.
1753 Suspend(region::Scope),
1756 impl Debug for ValidationOp {
1757 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1758 use self::ValidationOp::*;
1760 Acquire => write!(fmt, "Acquire"),
1761 Release => write!(fmt, "Release"),
1762 // (reuse lifetime rendering policy from ppaux.)
1763 Suspend(ref ce) => write!(fmt, "Suspend({})", ty::ReScope(*ce)),
1768 // This is generic so that it can be reused by miri
1769 #[derive(Clone, Hash, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1770 pub struct ValidationOperand<'tcx, T> {
1773 pub re: Option<region::Scope>,
1774 pub mutbl: hir::Mutability,
1777 impl<'tcx, T: Debug> Debug for ValidationOperand<'tcx, T> {
1778 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1779 write!(fmt, "{:?}: {:?}", self.place, self.ty)?;
1780 if let Some(ce) = self.re {
1781 // (reuse lifetime rendering policy from ppaux.)
1782 write!(fmt, "/{}", ty::ReScope(ce))?;
1784 if let hir::MutImmutable = self.mutbl {
1785 write!(fmt, " (imm)")?;
1791 impl<'tcx> Debug for Statement<'tcx> {
1792 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1793 use self::StatementKind::*;
1795 Assign(ref place, ref rv) => write!(fmt, "{:?} = {:?}", place, rv),
1796 FakeRead(ref cause, ref place) => write!(fmt, "FakeRead({:?}, {:?})", cause, place),
1797 // (reuse lifetime rendering policy from ppaux.)
1798 EndRegion(ref ce) => write!(fmt, "EndRegion({})", ty::ReScope(*ce)),
1799 Validate(ref op, ref places) => write!(fmt, "Validate({:?}, {:?})", op, places),
1800 StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place),
1801 StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place),
1805 } => write!(fmt, "discriminant({:?}) = {:?}", place, variant_index),
1810 } => write!(fmt, "asm!({:?} : {:?} : {:?})", asm, outputs, inputs),
1811 AscribeUserType(ref place, ref variance, ref c_ty) => {
1812 write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty)
1814 Nop => write!(fmt, "nop"),
1819 ///////////////////////////////////////////////////////////////////////////
1822 /// A path to a value; something that can be evaluated without
1823 /// changing or disturbing program state.
1824 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1825 pub enum Place<'tcx> {
1829 /// static or static mut variable
1830 Static(Box<Static<'tcx>>),
1832 /// Constant code promoted to an injected static
1833 Promoted(Box<(Promoted, Ty<'tcx>)>),
1835 /// projection out of a place (access a field, deref a pointer, etc)
1836 Projection(Box<PlaceProjection<'tcx>>),
1839 /// The def-id of a static, along with its normalized type (which is
1840 /// stored to avoid requiring normalization when reading MIR).
1841 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1842 pub struct Static<'tcx> {
1847 impl_stable_hash_for!(struct Static<'tcx> {
1852 /// The `Projection` data structure defines things of the form `B.x`
1853 /// or `*B` or `B[index]`. Note that it is parameterized because it is
1854 /// shared between `Constant` and `Place`. See the aliases
1855 /// `PlaceProjection` etc below.
1856 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1857 pub struct Projection<'tcx, B, V, T> {
1859 pub elem: ProjectionElem<'tcx, V, T>,
1862 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1863 pub enum ProjectionElem<'tcx, V, T> {
1868 /// These indices are generated by slice patterns. Easiest to explain
1872 /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
1873 /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
1874 /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
1875 /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
1878 /// index or -index (in Python terms), depending on from_end
1880 /// thing being indexed must be at least this long
1882 /// counting backwards from end?
1886 /// These indices are generated by slice patterns.
1888 /// slice[from:-to] in Python terms.
1894 /// "Downcast" to a variant of an ADT. Currently, we only introduce
1895 /// this for ADTs with more than one variant. It may be better to
1896 /// just introduce it always, or always for enums.
1897 Downcast(&'tcx AdtDef, usize),
1900 /// Alias for projections as they appear in places, where the base is a place
1901 /// and the index is a local.
1902 pub type PlaceProjection<'tcx> = Projection<'tcx, Place<'tcx>, Local, Ty<'tcx>>;
1904 /// Alias for projections as they appear in places, where the base is a place
1905 /// and the index is a local.
1906 pub type PlaceElem<'tcx> = ProjectionElem<'tcx, Local, Ty<'tcx>>;
1910 DEBUG_FORMAT = "field[{}]"
1914 impl<'tcx> Place<'tcx> {
1915 pub fn field(self, f: Field, ty: Ty<'tcx>) -> Place<'tcx> {
1916 self.elem(ProjectionElem::Field(f, ty))
1919 pub fn deref(self) -> Place<'tcx> {
1920 self.elem(ProjectionElem::Deref)
1923 pub fn downcast(self, adt_def: &'tcx AdtDef, variant_index: usize) -> Place<'tcx> {
1924 self.elem(ProjectionElem::Downcast(adt_def, variant_index))
1927 pub fn index(self, index: Local) -> Place<'tcx> {
1928 self.elem(ProjectionElem::Index(index))
1931 pub fn elem(self, elem: PlaceElem<'tcx>) -> Place<'tcx> {
1932 Place::Projection(Box::new(PlaceProjection { base: self, elem }))
1935 /// Find the innermost `Local` from this `Place`.
1936 pub fn local(&self) -> Option<Local> {
1938 Place::Local(local) |
1939 Place::Projection(box Projection {
1940 base: Place::Local(local),
1941 elem: ProjectionElem::Deref,
1948 impl<'tcx> Debug for Place<'tcx> {
1949 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1953 Local(id) => write!(fmt, "{:?}", id),
1954 Static(box self::Static { def_id, ty }) => write!(
1957 ty::tls::with(|tcx| tcx.item_path_str(def_id)),
1960 Promoted(ref promoted) => write!(fmt, "({:?}: {:?})", promoted.0, promoted.1),
1961 Projection(ref data) => match data.elem {
1962 ProjectionElem::Downcast(ref adt_def, index) => {
1963 write!(fmt, "({:?} as {})", data.base, adt_def.variants[index].name)
1965 ProjectionElem::Deref => write!(fmt, "(*{:?})", data.base),
1966 ProjectionElem::Field(field, ty) => {
1967 write!(fmt, "({:?}.{:?}: {:?})", data.base, field.index(), ty)
1969 ProjectionElem::Index(ref index) => write!(fmt, "{:?}[{:?}]", data.base, index),
1970 ProjectionElem::ConstantIndex {
1974 } => write!(fmt, "{:?}[{:?} of {:?}]", data.base, offset, min_length),
1975 ProjectionElem::ConstantIndex {
1979 } => write!(fmt, "{:?}[-{:?} of {:?}]", data.base, offset, min_length),
1980 ProjectionElem::Subslice { from, to } if to == 0 => {
1981 write!(fmt, "{:?}[{:?}:]", data.base, from)
1983 ProjectionElem::Subslice { from, to } if from == 0 => {
1984 write!(fmt, "{:?}[:-{:?}]", data.base, to)
1986 ProjectionElem::Subslice { from, to } => {
1987 write!(fmt, "{:?}[{:?}:-{:?}]", data.base, from, to)
1994 ///////////////////////////////////////////////////////////////////////////
1998 pub struct SourceScope {
1999 DEBUG_FORMAT = "scope[{}]",
2000 const OUTERMOST_SOURCE_SCOPE = 0,
2004 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2005 pub struct SourceScopeData {
2007 pub parent_scope: Option<SourceScope>,
2010 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2011 pub struct SourceScopeLocalData {
2012 /// A NodeId with lint levels equivalent to this scope's lint levels.
2013 pub lint_root: ast::NodeId,
2014 /// The unsafe block that contains this node.
2018 ///////////////////////////////////////////////////////////////////////////
2021 /// These are values that can appear inside an rvalue (or an index
2022 /// place). They are intentionally limited to prevent rvalues from
2023 /// being nested in one another.
2024 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
2025 pub enum Operand<'tcx> {
2026 /// Copy: The value must be available for use afterwards.
2028 /// This implies that the type of the place must be `Copy`; this is true
2029 /// by construction during build, but also checked by the MIR type checker.
2032 /// Move: The value (including old borrows of it) will not be used again.
2034 /// Safe for values of all types (modulo future developments towards `?Move`).
2035 /// Correct usage patterns are enforced by the borrow checker for safe code.
2036 /// `Copy` may be converted to `Move` to enable "last-use" optimizations.
2039 /// Synthesizes a constant value.
2040 Constant(Box<Constant<'tcx>>),
2043 impl<'tcx> Debug for Operand<'tcx> {
2044 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2045 use self::Operand::*;
2047 Constant(ref a) => write!(fmt, "{:?}", a),
2048 Copy(ref place) => write!(fmt, "{:?}", place),
2049 Move(ref place) => write!(fmt, "move {:?}", place),
2054 impl<'tcx> Operand<'tcx> {
2055 /// Convenience helper to make a constant that refers to the fn
2056 /// with given def-id and substs. Since this is used to synthesize
2057 /// MIR, assumes `user_ty` is None.
2058 pub fn function_handle<'a>(
2059 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2061 substs: &'tcx Substs<'tcx>,
2064 let ty = tcx.type_of(def_id).subst(tcx, substs);
2065 Operand::Constant(box Constant {
2069 literal: ty::Const::zero_sized(tcx, ty),
2073 pub fn to_copy(&self) -> Self {
2075 Operand::Copy(_) | Operand::Constant(_) => self.clone(),
2076 Operand::Move(ref place) => Operand::Copy(place.clone()),
2081 ///////////////////////////////////////////////////////////////////////////
2084 #[derive(Clone, RustcEncodable, RustcDecodable)]
2085 pub enum Rvalue<'tcx> {
2086 /// x (either a move or copy, depending on type of x)
2090 Repeat(Operand<'tcx>, u64),
2093 Ref(Region<'tcx>, BorrowKind, Place<'tcx>),
2095 /// length of a [X] or [X;n] value
2098 Cast(CastKind, Operand<'tcx>, Ty<'tcx>),
2100 BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
2101 CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
2103 NullaryOp(NullOp, Ty<'tcx>),
2104 UnaryOp(UnOp, Operand<'tcx>),
2106 /// Read the discriminant of an ADT.
2108 /// Undefined (i.e. no effort is made to make it defined, but there’s no reason why it cannot
2109 /// be defined to return, say, a 0) if ADT is not an enum.
2110 Discriminant(Place<'tcx>),
2112 /// Create an aggregate value, like a tuple or struct. This is
2113 /// only needed because we want to distinguish `dest = Foo { x:
2114 /// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case
2115 /// that `Foo` has a destructor. These rvalues can be optimized
2116 /// away after type-checking and before lowering.
2117 Aggregate(Box<AggregateKind<'tcx>>, Vec<Operand<'tcx>>),
2120 #[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2124 /// Convert unique, zero-sized type for a fn to fn()
2127 /// Convert non capturing closure to fn()
2130 /// Convert safe fn() to unsafe fn()
2133 /// "Unsize" -- convert a thin-or-fat pointer to a fat pointer.
2134 /// codegen must figure out the details once full monomorphization
2135 /// is known. For example, this could be used to cast from a
2136 /// `&[i32;N]` to a `&[i32]`, or a `Box<T>` to a `Box<Trait>`
2137 /// (presuming `T: Trait`).
2141 #[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2142 pub enum AggregateKind<'tcx> {
2143 /// The type is of the element
2147 /// The second field is the variant index. It's equal to 0 for struct
2148 /// and union expressions. The fourth field is
2149 /// active field number and is present only for union expressions
2150 /// -- e.g. for a union expression `SomeUnion { c: .. }`, the
2151 /// active field index would identity the field `c`
2156 Option<CanonicalTy<'tcx>>,
2160 Closure(DefId, ClosureSubsts<'tcx>),
2161 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
2164 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2166 /// The `+` operator (addition)
2168 /// The `-` operator (subtraction)
2170 /// The `*` operator (multiplication)
2172 /// The `/` operator (division)
2174 /// The `%` operator (modulus)
2176 /// The `^` operator (bitwise xor)
2178 /// The `&` operator (bitwise and)
2180 /// The `|` operator (bitwise or)
2182 /// The `<<` operator (shift left)
2184 /// The `>>` operator (shift right)
2186 /// The `==` operator (equality)
2188 /// The `<` operator (less than)
2190 /// The `<=` operator (less than or equal to)
2192 /// The `!=` operator (not equal to)
2194 /// The `>=` operator (greater than or equal to)
2196 /// The `>` operator (greater than)
2198 /// The `ptr.offset` operator
2203 pub fn is_checkable(self) -> bool {
2206 Add | Sub | Mul | Shl | Shr => true,
2212 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2214 /// Return the size of a value of that type
2216 /// Create a new uninitialized box for a value of that type
2220 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2222 /// The `!` operator for logical inversion
2224 /// The `-` operator for negation
2228 impl<'tcx> Debug for Rvalue<'tcx> {
2229 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2230 use self::Rvalue::*;
2233 Use(ref place) => write!(fmt, "{:?}", place),
2234 Repeat(ref a, ref b) => write!(fmt, "[{:?}; {:?}]", a, b),
2235 Len(ref a) => write!(fmt, "Len({:?})", a),
2236 Cast(ref kind, ref place, ref ty) => {
2237 write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind)
2239 BinaryOp(ref op, ref a, ref b) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
2240 CheckedBinaryOp(ref op, ref a, ref b) => {
2241 write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b)
2243 UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
2244 Discriminant(ref place) => write!(fmt, "discriminant({:?})", place),
2245 NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
2246 Ref(region, borrow_kind, ref place) => {
2247 let kind_str = match borrow_kind {
2248 BorrowKind::Shared => "",
2249 BorrowKind::Shallow => "shallow ",
2250 BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ",
2253 // When printing regions, add trailing space if necessary.
2254 let region = if ppaux::verbose() || ppaux::identify_regions() {
2255 let mut region = region.to_string();
2256 if region.len() > 0 {
2261 // Do not even print 'static
2264 write!(fmt, "&{}{}{:?}", region, kind_str, place)
2267 Aggregate(ref kind, ref places) => {
2268 fn fmt_tuple(fmt: &mut Formatter<'_>, places: &[Operand<'_>]) -> fmt::Result {
2269 let mut tuple_fmt = fmt.debug_tuple("");
2270 for place in places {
2271 tuple_fmt.field(place);
2277 AggregateKind::Array(_) => write!(fmt, "{:?}", places),
2279 AggregateKind::Tuple => match places.len() {
2280 0 => write!(fmt, "()"),
2281 1 => write!(fmt, "({:?},)", places[0]),
2282 _ => fmt_tuple(fmt, places),
2285 AggregateKind::Adt(adt_def, variant, substs, _user_ty, _) => {
2286 let variant_def = &adt_def.variants[variant];
2288 ppaux::parameterized(fmt, substs, variant_def.did, &[])?;
2290 match variant_def.ctor_kind {
2291 CtorKind::Const => Ok(()),
2292 CtorKind::Fn => fmt_tuple(fmt, places),
2293 CtorKind::Fictive => {
2294 let mut struct_fmt = fmt.debug_struct("");
2295 for (field, place) in variant_def.fields.iter().zip(places) {
2296 struct_fmt.field(&field.ident.as_str(), place);
2303 AggregateKind::Closure(def_id, _) => ty::tls::with(|tcx| {
2304 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2305 let name = if tcx.sess.opts.debugging_opts.span_free_formats {
2306 format!("[closure@{:?}]", node_id)
2308 format!("[closure@{:?}]", tcx.hir.span(node_id))
2310 let mut struct_fmt = fmt.debug_struct(&name);
2312 tcx.with_freevars(node_id, |freevars| {
2313 for (freevar, place) in freevars.iter().zip(places) {
2314 let var_name = tcx.hir.name(freevar.var_id());
2315 struct_fmt.field(&var_name.as_str(), place);
2321 write!(fmt, "[closure]")
2325 AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
2326 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2327 let name = format!("[generator@{:?}]", tcx.hir.span(node_id));
2328 let mut struct_fmt = fmt.debug_struct(&name);
2330 tcx.with_freevars(node_id, |freevars| {
2331 for (freevar, place) in freevars.iter().zip(places) {
2332 let var_name = tcx.hir.name(freevar.var_id());
2333 struct_fmt.field(&var_name.as_str(), place);
2335 struct_fmt.field("$state", &places[freevars.len()]);
2336 for i in (freevars.len() + 1)..places.len() {
2338 .field(&format!("${}", i - freevars.len() - 1), &places[i]);
2344 write!(fmt, "[generator]")
2353 ///////////////////////////////////////////////////////////////////////////
2356 /// Two constants are equal if they are the same constant. Note that
2357 /// this does not necessarily mean that they are "==" in Rust -- in
2358 /// particular one must be wary of `NaN`!
2360 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2361 pub struct Constant<'tcx> {
2365 /// Optional user-given type: for something like
2366 /// `collect::<Vec<_>>`, this would be present and would
2367 /// indicate that `Vec<_>` was explicitly specified.
2369 /// Needed for NLL to impose user-given type constraints.
2370 pub user_ty: Option<CanonicalTy<'tcx>>,
2372 pub literal: &'tcx ty::Const<'tcx>,
2376 pub struct Promoted {
2377 DEBUG_FORMAT = "promoted[{}]"
2381 impl<'tcx> Debug for Constant<'tcx> {
2382 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2383 write!(fmt, "const ")?;
2384 fmt_const_val(fmt, self.literal)
2388 /// Write a `ConstValue` in a way closer to the original source code than the `Debug` output.
2389 pub fn fmt_const_val(f: &mut impl Write, const_val: &ty::Const<'_>) -> fmt::Result {
2391 let value = const_val.val;
2392 let ty = const_val.ty;
2393 // print some primitives
2394 if let ConstValue::Scalar(Scalar::Bits { bits, .. }) = value {
2396 Bool if bits == 0 => return write!(f, "false"),
2397 Bool if bits == 1 => return write!(f, "true"),
2398 Float(ast::FloatTy::F32) => return write!(f, "{}f32", Single::from_bits(bits)),
2399 Float(ast::FloatTy::F64) => return write!(f, "{}f64", Double::from_bits(bits)),
2400 Uint(ui) => return write!(f, "{:?}{}", bits, ui),
2402 let bit_width = ty::tls::with(|tcx| {
2403 let ty = tcx.lift_to_global(&ty).unwrap();
2404 tcx.layout_of(ty::ParamEnv::empty().and(ty))
2409 let shift = 128 - bit_width;
2410 return write!(f, "{:?}{}", ((bits as i128) << shift) >> shift, i);
2412 Char => return write!(f, "{:?}", ::std::char::from_u32(bits as u32).unwrap()),
2416 // print function definitons
2417 if let FnDef(did, _) = ty.sty {
2418 return write!(f, "{}", item_path_str(did));
2420 // print string literals
2421 if let ConstValue::ScalarPair(ptr, len) = value {
2422 if let Scalar::Ptr(ptr) = ptr {
2423 if let Scalar::Bits { bits: len, .. } = len {
2424 if let Ref(_, &ty::TyS { sty: Str, .. }, _) = ty.sty {
2425 return ty::tls::with(|tcx| {
2426 let alloc = tcx.alloc_map.lock().get(ptr.alloc_id);
2427 if let Some(interpret::AllocType::Memory(alloc)) = alloc {
2428 assert_eq!(len as usize as u128, len);
2430 &alloc.bytes[(ptr.offset.bytes() as usize)..][..(len as usize)];
2431 let s = ::std::str::from_utf8(slice).expect("non utf8 str from miri");
2432 write!(f, "{:?}", s)
2434 write!(f, "pointer to erroneous constant {:?}, {:?}", ptr, len)
2441 // just raw dump everything else
2442 write!(f, "{:?}:{}", value, ty)
2445 fn item_path_str(def_id: DefId) -> String {
2446 ty::tls::with(|tcx| tcx.item_path_str(def_id))
2449 impl<'tcx> graph::DirectedGraph for Mir<'tcx> {
2450 type Node = BasicBlock;
2453 impl<'tcx> graph::WithNumNodes for Mir<'tcx> {
2454 fn num_nodes(&self) -> usize {
2455 self.basic_blocks.len()
2459 impl<'tcx> graph::WithStartNode for Mir<'tcx> {
2460 fn start_node(&self) -> Self::Node {
2465 impl<'tcx> graph::WithPredecessors for Mir<'tcx> {
2466 fn predecessors<'graph>(
2469 ) -> <Self as GraphPredecessors<'graph>>::Iter {
2470 self.predecessors_for(node).clone().into_iter()
2474 impl<'tcx> graph::WithSuccessors for Mir<'tcx> {
2475 fn successors<'graph>(
2478 ) -> <Self as GraphSuccessors<'graph>>::Iter {
2479 self.basic_blocks[node].terminator().successors().cloned()
2483 impl<'a, 'b> graph::GraphPredecessors<'b> for Mir<'a> {
2484 type Item = BasicBlock;
2485 type Iter = IntoIter<BasicBlock>;
2488 impl<'a, 'b> graph::GraphSuccessors<'b> for Mir<'a> {
2489 type Item = BasicBlock;
2490 type Iter = iter::Cloned<Successors<'b>>;
2493 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
2494 pub struct Location {
2495 /// the location is within this block
2496 pub block: BasicBlock,
2498 /// the location is the start of the statement; or, if `statement_index`
2499 /// == num-statements, then the start of the terminator.
2500 pub statement_index: usize,
2503 impl fmt::Debug for Location {
2504 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2505 write!(fmt, "{:?}[{}]", self.block, self.statement_index)
2510 pub const START: Location = Location {
2515 /// Returns the location immediately after this one within the enclosing block.
2517 /// Note that if this location represents a terminator, then the
2518 /// resulting location would be out of bounds and invalid.
2519 pub fn successor_within_block(&self) -> Location {
2522 statement_index: self.statement_index + 1,
2526 pub fn dominates(&self, other: Location, dominators: &Dominators<BasicBlock>) -> bool {
2527 if self.block == other.block {
2528 self.statement_index <= other.statement_index
2530 dominators.is_dominated_by(other.block, self.block)
2535 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2536 pub enum UnsafetyViolationKind {
2538 /// unsafety is not allowed at all in min const fn
2540 ExternStatic(ast::NodeId),
2541 BorrowPacked(ast::NodeId),
2544 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2545 pub struct UnsafetyViolation {
2546 pub source_info: SourceInfo,
2547 pub description: InternedString,
2548 pub details: InternedString,
2549 pub kind: UnsafetyViolationKind,
2552 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2553 pub struct UnsafetyCheckResult {
2554 /// Violations that are propagated *upwards* from this function
2555 pub violations: Lrc<[UnsafetyViolation]>,
2556 /// unsafe blocks in this function, along with whether they are used. This is
2557 /// used for the "unused_unsafe" lint.
2558 pub unsafe_blocks: Lrc<[(ast::NodeId, bool)]>,
2561 /// The layout of generator state
2562 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2563 pub struct GeneratorLayout<'tcx> {
2564 pub fields: Vec<LocalDecl<'tcx>>,
2567 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2568 pub struct BorrowCheckResult<'gcx> {
2569 pub closure_requirements: Option<ClosureRegionRequirements<'gcx>>,
2570 pub used_mut_upvars: SmallVec<[Field; 8]>,
2573 /// After we borrow check a closure, we are left with various
2574 /// requirements that we have inferred between the free regions that
2575 /// appear in the closure's signature or on its field types. These
2576 /// requirements are then verified and proved by the closure's
2577 /// creating function. This struct encodes those requirements.
2579 /// The requirements are listed as being between various
2580 /// `RegionVid`. The 0th region refers to `'static`; subsequent region
2581 /// vids refer to the free regions that appear in the closure (or
2582 /// generator's) type, in order of appearance. (This numbering is
2583 /// actually defined by the `UniversalRegions` struct in the NLL
2584 /// region checker. See for example
2585 /// `UniversalRegions::closure_mapping`.) Note that we treat the free
2586 /// regions in the closure's type "as if" they were erased, so their
2587 /// precise identity is not important, only their position.
2589 /// Example: If type check produces a closure with the closure substs:
2592 /// ClosureSubsts = [
2593 /// i8, // the "closure kind"
2594 /// for<'x> fn(&'a &'x u32) -> &'x u32, // the "closure signature"
2595 /// &'a String, // some upvar
2599 /// here, there is one unique free region (`'a`) but it appears
2600 /// twice. We would "renumber" each occurrence to a unique vid, as follows:
2603 /// ClosureSubsts = [
2604 /// i8, // the "closure kind"
2605 /// for<'x> fn(&'1 &'x u32) -> &'x u32, // the "closure signature"
2606 /// &'2 String, // some upvar
2610 /// Now the code might impose a requirement like `'1: '2`. When an
2611 /// instance of the closure is created, the corresponding free regions
2612 /// can be extracted from its type and constrained to have the given
2613 /// outlives relationship.
2615 /// In some cases, we have to record outlives requirements between
2616 /// types and regions as well. In that case, if those types include
2617 /// any regions, those regions are recorded as `ReClosureBound`
2618 /// instances assigned one of these same indices. Those regions will
2619 /// be substituted away by the creator. We use `ReClosureBound` in
2620 /// that case because the regions must be allocated in the global
2621 /// TyCtxt, and hence we cannot use `ReVar` (which is what we use
2622 /// internally within the rest of the NLL code).
2623 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2624 pub struct ClosureRegionRequirements<'gcx> {
2625 /// The number of external regions defined on the closure. In our
2626 /// example above, it would be 3 -- one for `'static`, then `'1`
2627 /// and `'2`. This is just used for a sanity check later on, to
2628 /// make sure that the number of regions we see at the callsite
2630 pub num_external_vids: usize,
2632 /// Requirements between the various free regions defined in
2634 pub outlives_requirements: Vec<ClosureOutlivesRequirement<'gcx>>,
2637 /// Indicates an outlives constraint between a type or between two
2638 /// free-regions declared on the closure.
2639 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2640 pub struct ClosureOutlivesRequirement<'tcx> {
2641 // This region or type ...
2642 pub subject: ClosureOutlivesSubject<'tcx>,
2644 // .. must outlive this one.
2645 pub outlived_free_region: ty::RegionVid,
2647 // If not, report an error here.
2648 pub blame_span: Span,
2651 /// The subject of a ClosureOutlivesRequirement -- that is, the thing
2652 /// that must outlive some region.
2653 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2654 pub enum ClosureOutlivesSubject<'tcx> {
2655 /// Subject is a type, typically a type parameter, but could also
2656 /// be a projection. Indicates a requirement like `T: 'a` being
2657 /// passed to the caller, where the type here is `T`.
2659 /// The type here is guaranteed not to contain any free regions at
2663 /// Subject is a free region from the closure. Indicates a requirement
2664 /// like `'a: 'b` being passed to the caller; the region here is `'a`.
2665 Region(ty::RegionVid),
2669 * TypeFoldable implementations for MIR types
2672 CloneTypeFoldableAndLiftImpls! {
2680 SourceScopeLocalData,
2683 BraceStructTypeFoldableImpl! {
2684 impl<'tcx> TypeFoldable<'tcx> for Mir<'tcx> {
2687 source_scope_local_data,
2701 BraceStructTypeFoldableImpl! {
2702 impl<'tcx> TypeFoldable<'tcx> for GeneratorLayout<'tcx> {
2707 BraceStructTypeFoldableImpl! {
2708 impl<'tcx> TypeFoldable<'tcx> for LocalDecl<'tcx> {
2720 BraceStructTypeFoldableImpl! {
2721 impl<'tcx> TypeFoldable<'tcx> for BasicBlockData<'tcx> {
2728 BraceStructTypeFoldableImpl! {
2729 impl<'tcx> TypeFoldable<'tcx> for ValidationOperand<'tcx, Place<'tcx>> {
2730 place, ty, re, mutbl
2734 BraceStructTypeFoldableImpl! {
2735 impl<'tcx> TypeFoldable<'tcx> for Statement<'tcx> {
2740 EnumTypeFoldableImpl! {
2741 impl<'tcx> TypeFoldable<'tcx> for StatementKind<'tcx> {
2742 (StatementKind::Assign)(a, b),
2743 (StatementKind::FakeRead)(cause, place),
2744 (StatementKind::SetDiscriminant) { place, variant_index },
2745 (StatementKind::StorageLive)(a),
2746 (StatementKind::StorageDead)(a),
2747 (StatementKind::InlineAsm) { asm, outputs, inputs },
2748 (StatementKind::Validate)(a, b),
2749 (StatementKind::EndRegion)(a),
2750 (StatementKind::AscribeUserType)(a, v, b),
2751 (StatementKind::Nop),
2755 EnumTypeFoldableImpl! {
2756 impl<'tcx, T> TypeFoldable<'tcx> for ClearCrossCrate<T> {
2757 (ClearCrossCrate::Clear),
2758 (ClearCrossCrate::Set)(a),
2759 } where T: TypeFoldable<'tcx>
2762 impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
2763 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2764 use mir::TerminatorKind::*;
2766 let kind = match self.kind {
2767 Goto { target } => Goto { target: target },
2774 discr: discr.fold_with(folder),
2775 switch_ty: switch_ty.fold_with(folder),
2776 values: values.clone(),
2777 targets: targets.clone(),
2784 location: location.fold_with(folder),
2793 } => DropAndReplace {
2794 location: location.fold_with(folder),
2795 value: value.fold_with(folder),
2804 value: value.fold_with(folder),
2814 let dest = destination
2816 .map(|&(ref loc, dest)| (loc.fold_with(folder), dest));
2819 func: func.fold_with(folder),
2820 args: args.fold_with(folder),
2832 let msg = if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
2833 EvalErrorKind::BoundsCheck {
2834 len: len.fold_with(folder),
2835 index: index.fold_with(folder),
2841 cond: cond.fold_with(folder),
2848 GeneratorDrop => GeneratorDrop,
2852 Unreachable => Unreachable,
2855 ref imaginary_targets,
2858 imaginary_targets: imaginary_targets.clone(),
2869 source_info: self.source_info,
2874 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2875 use mir::TerminatorKind::*;
2882 } => discr.visit_with(visitor) || switch_ty.visit_with(visitor),
2883 Drop { ref location, .. } => location.visit_with(visitor),
2888 } => location.visit_with(visitor) || value.visit_with(visitor),
2889 Yield { ref value, .. } => value.visit_with(visitor),
2896 let dest = if let Some((ref loc, _)) = *destination {
2897 loc.visit_with(visitor)
2901 dest || func.visit_with(visitor) || args.visit_with(visitor)
2904 ref cond, ref msg, ..
2906 if cond.visit_with(visitor) {
2907 if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
2908 len.visit_with(visitor) || index.visit_with(visitor)
2923 | FalseUnwind { .. } => false,
2928 impl<'tcx> TypeFoldable<'tcx> for Place<'tcx> {
2929 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2931 &Place::Projection(ref p) => Place::Projection(p.fold_with(folder)),
2936 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2937 if let &Place::Projection(ref p) = self {
2938 p.visit_with(visitor)
2945 impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
2946 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2949 Use(ref op) => Use(op.fold_with(folder)),
2950 Repeat(ref op, len) => Repeat(op.fold_with(folder), len),
2951 Ref(region, bk, ref place) => {
2952 Ref(region.fold_with(folder), bk, place.fold_with(folder))
2954 Len(ref place) => Len(place.fold_with(folder)),
2955 Cast(kind, ref op, ty) => Cast(kind, op.fold_with(folder), ty.fold_with(folder)),
2956 BinaryOp(op, ref rhs, ref lhs) => {
2957 BinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
2959 CheckedBinaryOp(op, ref rhs, ref lhs) => {
2960 CheckedBinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
2962 UnaryOp(op, ref val) => UnaryOp(op, val.fold_with(folder)),
2963 Discriminant(ref place) => Discriminant(place.fold_with(folder)),
2964 NullaryOp(op, ty) => NullaryOp(op, ty.fold_with(folder)),
2965 Aggregate(ref kind, ref fields) => {
2966 let kind = box match **kind {
2967 AggregateKind::Array(ty) => AggregateKind::Array(ty.fold_with(folder)),
2968 AggregateKind::Tuple => AggregateKind::Tuple,
2969 AggregateKind::Adt(def, v, substs, user_ty, n) => AggregateKind::Adt(
2972 substs.fold_with(folder),
2973 user_ty.fold_with(folder),
2976 AggregateKind::Closure(id, substs) => {
2977 AggregateKind::Closure(id, substs.fold_with(folder))
2979 AggregateKind::Generator(id, substs, movablity) => {
2980 AggregateKind::Generator(id, substs.fold_with(folder), movablity)
2983 Aggregate(kind, fields.fold_with(folder))
2988 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2991 Use(ref op) => op.visit_with(visitor),
2992 Repeat(ref op, _) => op.visit_with(visitor),
2993 Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor),
2994 Len(ref place) => place.visit_with(visitor),
2995 Cast(_, ref op, ty) => op.visit_with(visitor) || ty.visit_with(visitor),
2996 BinaryOp(_, ref rhs, ref lhs) | CheckedBinaryOp(_, ref rhs, ref lhs) => {
2997 rhs.visit_with(visitor) || lhs.visit_with(visitor)
2999 UnaryOp(_, ref val) => val.visit_with(visitor),
3000 Discriminant(ref place) => place.visit_with(visitor),
3001 NullaryOp(_, ty) => ty.visit_with(visitor),
3002 Aggregate(ref kind, ref fields) => {
3004 AggregateKind::Array(ty) => ty.visit_with(visitor),
3005 AggregateKind::Tuple => false,
3006 AggregateKind::Adt(_, _, substs, user_ty, _) => {
3007 substs.visit_with(visitor) || user_ty.visit_with(visitor)
3009 AggregateKind::Closure(_, substs) => substs.visit_with(visitor),
3010 AggregateKind::Generator(_, substs, _) => substs.visit_with(visitor),
3011 }) || fields.visit_with(visitor)
3017 impl<'tcx> TypeFoldable<'tcx> for Operand<'tcx> {
3018 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3020 Operand::Copy(ref place) => Operand::Copy(place.fold_with(folder)),
3021 Operand::Move(ref place) => Operand::Move(place.fold_with(folder)),
3022 Operand::Constant(ref c) => Operand::Constant(c.fold_with(folder)),
3026 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
3028 Operand::Copy(ref place) | Operand::Move(ref place) => place.visit_with(visitor),
3029 Operand::Constant(ref c) => c.visit_with(visitor),
3034 impl<'tcx, B, V, T> TypeFoldable<'tcx> for Projection<'tcx, B, V, T>
3036 B: TypeFoldable<'tcx>,
3037 V: TypeFoldable<'tcx>,
3038 T: TypeFoldable<'tcx>,
3040 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3041 use mir::ProjectionElem::*;
3043 let base = self.base.fold_with(folder);
3044 let elem = match self.elem {
3046 Field(f, ref ty) => Field(f, ty.fold_with(folder)),
3047 Index(ref v) => Index(v.fold_with(folder)),
3048 ref elem => elem.clone(),
3051 Projection { base, elem }
3054 fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool {
3055 use mir::ProjectionElem::*;
3057 self.base.visit_with(visitor) || match self.elem {
3058 Field(_, ref ty) => ty.visit_with(visitor),
3059 Index(ref v) => v.visit_with(visitor),
3065 impl<'tcx> TypeFoldable<'tcx> for Field {
3066 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _: &mut F) -> Self {
3069 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
3074 impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> {
3075 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3077 span: self.span.clone(),
3078 ty: self.ty.fold_with(folder),
3079 user_ty: self.user_ty.fold_with(folder),
3080 literal: self.literal.fold_with(folder),
3083 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
3084 self.ty.visit_with(visitor) || self.literal.visit_with(visitor)