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, ScalarMaybeUndef};
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, 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.
587 /// Reference used in a guard expression to ensure immutability.
591 CloneTypeFoldableAndLiftImpls! { BindingForm<'tcx>, }
593 impl_stable_hash_for!(struct self::VarBindingForm<'tcx> {
600 mod binding_form_impl {
601 use ich::StableHashingContext;
602 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableHasherResult};
604 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
605 fn hash_stable<W: StableHasherResult>(
607 hcx: &mut StableHashingContext<'a>,
608 hasher: &mut StableHasher<W>,
610 use super::BindingForm::*;
611 ::std::mem::discriminant(self).hash_stable(hcx, hasher);
614 Var(binding) => binding.hash_stable(hcx, hasher),
624 /// This can be a binding declared by the user, a temporary inserted by the compiler, a function
625 /// argument, or the return place.
626 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
627 pub struct LocalDecl<'tcx> {
628 /// `let mut x` vs `let x`.
630 /// Temporaries and the return place are always mutable.
631 pub mutability: Mutability,
633 /// Some(binding_mode) if this corresponds to a user-declared local variable.
635 /// This is solely used for local diagnostics when generating
636 /// warnings/errors when compiling the current crate, and
637 /// therefore it need not be visible across crates. pnkfelix
638 /// currently hypothesized we *need* to wrap this in a
639 /// `ClearCrossCrate` as long as it carries as `HirId`.
640 pub is_user_variable: Option<ClearCrossCrate<BindingForm<'tcx>>>,
642 /// True if this is an internal local
644 /// These locals are not based on types in the source code and are only used
645 /// for a few desugarings at the moment.
647 /// The generator transformation will sanity check the locals which are live
648 /// across a suspension point against the type components of the generator
649 /// which type checking knows are live across a suspension point. We need to
650 /// flag drop flags to avoid triggering this check as they are introduced
653 /// Unsafety checking will also ignore dereferences of these locals,
654 /// so they can be used for raw pointers only used in a desugaring.
656 /// This should be sound because the drop flags are fully algebraic, and
657 /// therefore don't affect the OIBIT or outlives properties of the
661 /// Type of this local.
664 /// If the user manually ascribed a type to this variable,
665 /// e.g. via `let x: T`, then we carry that type here. The MIR
666 /// borrow checker needs this information since it can affect
667 /// region inference.
668 pub user_ty: Option<CanonicalTy<'tcx>>,
670 /// Name of the local, used in debuginfo and pretty-printing.
672 /// Note that function arguments can also have this set to `Some(_)`
673 /// to generate better debuginfo.
674 pub name: Option<Name>,
676 /// The *syntactic* (i.e. not visibility) source scope the local is defined
677 /// in. If the local was defined in a let-statement, this
678 /// is *within* the let-statement, rather than outside
681 /// This is needed because the visibility source scope of locals within
682 /// a let-statement is weird.
684 /// The reason is that we want the local to be *within* the let-statement
685 /// for lint purposes, but we want the local to be *after* the let-statement
686 /// for names-in-scope purposes.
688 /// That's it, if we have a let-statement like the one in this
692 /// fn foo(x: &str) {
693 /// #[allow(unused_mut)]
694 /// let mut x: u32 = { // <- one unused mut
695 /// let mut y: u32 = x.parse().unwrap();
702 /// Then, from a lint point of view, the declaration of `x: u32`
703 /// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the
704 /// lint scopes are the same as the AST/HIR nesting.
706 /// However, from a name lookup point of view, the scopes look more like
707 /// as if the let-statements were `match` expressions:
710 /// fn foo(x: &str) {
712 /// match x.parse().unwrap() {
721 /// We care about the name-lookup scopes for debuginfo - if the
722 /// debuginfo instruction pointer is at the call to `x.parse()`, we
723 /// want `x` to refer to `x: &str`, but if it is at the call to
724 /// `drop(x)`, we want it to refer to `x: u32`.
726 /// To allow both uses to work, we need to have more than a single scope
727 /// for a local. We have the `source_info.scope` represent the
728 /// "syntactic" lint scope (with a variable being under its let
729 /// block) while the `visibility_scope` represents the "local variable"
730 /// scope (where the "rest" of a block is under all prior let-statements).
732 /// The end result looks like this:
736 /// │{ argument x: &str }
738 /// │ │{ #[allow(unused_mut)] } // this is actually split into 2 scopes
739 /// │ │ // in practice because I'm lazy.
741 /// │ │← x.source_info.scope
742 /// │ │← `x.parse().unwrap()`
744 /// │ │ │← y.source_info.scope
746 /// │ │ │{ let y: u32 }
748 /// │ │ │← y.visibility_scope
751 /// │ │{ let x: u32 }
752 /// │ │← x.visibility_scope
753 /// │ │← `drop(x)` // this accesses `x: u32`
755 pub source_info: SourceInfo,
757 /// Source scope within which the local is visible (for debuginfo)
758 /// (see `source_info` for more details).
759 pub visibility_scope: SourceScope,
762 impl<'tcx> LocalDecl<'tcx> {
763 /// Returns true only if local is a binding that can itself be
764 /// made mutable via the addition of the `mut` keyword, namely
765 /// something like the occurrences of `x` in:
766 /// - `fn foo(x: Type) { ... }`,
768 /// - or `match ... { C(x) => ... }`
769 pub fn can_be_made_mutable(&self) -> bool {
770 match self.is_user_variable {
771 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
772 binding_mode: ty::BindingMode::BindByValue(_),
778 // FIXME: might be able to thread the distinction between
779 // `self`/`mut self`/`&self`/`&mut self` into the
780 // `BindingForm::ImplicitSelf` variant, (and then return
781 // true here for solely the first case).
786 /// Returns true if local is definitely not a `ref ident` or
787 /// `ref mut ident` binding. (Such bindings cannot be made into
788 /// mutable bindings, but the inverse does not necessarily hold).
789 pub fn is_nonref_binding(&self) -> bool {
790 match self.is_user_variable {
791 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
792 binding_mode: ty::BindingMode::BindByValue(_),
798 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf)) => true,
804 /// Create a new `LocalDecl` for a temporary.
806 pub fn new_temp(ty: Ty<'tcx>, span: Span) -> Self {
807 Self::new_local(ty, Mutability::Mut, false, span)
810 /// Create a new immutable `LocalDecl` for a temporary.
812 pub fn new_immutable_temp(ty: Ty<'tcx>, span: Span) -> Self {
813 Self::new_local(ty, Mutability::Not, false, span)
816 /// Create a new `LocalDecl` for a internal temporary.
818 pub fn new_internal(ty: Ty<'tcx>, span: Span) -> Self {
819 Self::new_local(ty, Mutability::Mut, true, span)
825 mutability: Mutability,
834 source_info: SourceInfo {
836 scope: OUTERMOST_SOURCE_SCOPE,
838 visibility_scope: OUTERMOST_SOURCE_SCOPE,
840 is_user_variable: None,
844 /// Builds a `LocalDecl` for the return place.
846 /// This must be inserted into the `local_decls` list as the first local.
848 pub fn new_return_place(return_ty: Ty, span: Span) -> LocalDecl {
850 mutability: Mutability::Mut,
853 source_info: SourceInfo {
855 scope: OUTERMOST_SOURCE_SCOPE,
857 visibility_scope: OUTERMOST_SOURCE_SCOPE,
859 name: None, // FIXME maybe we do want some name here?
860 is_user_variable: None,
865 /// A closure capture, with its name and mode.
866 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
867 pub struct UpvarDecl {
868 pub debug_name: Name,
870 /// `HirId` of the captured variable
871 pub var_hir_id: ClearCrossCrate<HirId>,
873 /// If true, the capture is behind a reference.
876 pub mutability: Mutability,
879 ///////////////////////////////////////////////////////////////////////////
883 pub struct BasicBlock {
884 DEBUG_FORMAT = "bb{}",
885 const START_BLOCK = 0,
890 pub fn start_location(self) -> Location {
898 ///////////////////////////////////////////////////////////////////////////
899 // BasicBlockData and Terminator
901 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
902 pub struct BasicBlockData<'tcx> {
903 /// List of statements in this block.
904 pub statements: Vec<Statement<'tcx>>,
906 /// Terminator for this block.
908 /// NB. This should generally ONLY be `None` during construction.
909 /// Therefore, you should generally access it via the
910 /// `terminator()` or `terminator_mut()` methods. The only
911 /// exception is that certain passes, such as `simplify_cfg`, swap
912 /// out the terminator temporarily with `None` while they continue
913 /// to recurse over the set of basic blocks.
914 pub terminator: Option<Terminator<'tcx>>,
916 /// If true, this block lies on an unwind path. This is used
917 /// during codegen where distinct kinds of basic blocks may be
918 /// generated (particularly for MSVC cleanup). Unwind blocks must
919 /// only branch to other unwind blocks.
920 pub is_cleanup: bool,
923 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
924 pub struct Terminator<'tcx> {
925 pub source_info: SourceInfo,
926 pub kind: TerminatorKind<'tcx>,
929 #[derive(Clone, RustcEncodable, RustcDecodable)]
930 pub enum TerminatorKind<'tcx> {
931 /// block should have one successor in the graph; we jump there
932 Goto { target: BasicBlock },
934 /// operand evaluates to an integer; jump depending on its value
935 /// to one of the targets, and otherwise fallback to `otherwise`
937 /// discriminant value being tested
938 discr: Operand<'tcx>,
940 /// type of value being tested
943 /// Possible values. The locations to branch to in each case
944 /// are found in the corresponding indices from the `targets` vector.
945 values: Cow<'tcx, [u128]>,
947 /// Possible branch sites. The last element of this vector is used
948 /// for the otherwise branch, so targets.len() == values.len() + 1
950 // This invariant is quite non-obvious and also could be improved.
951 // One way to make this invariant is to have something like this instead:
953 // branches: Vec<(ConstInt, BasicBlock)>,
954 // otherwise: Option<BasicBlock> // exhaustive if None
956 // However we’ve decided to keep this as-is until we figure a case
957 // where some other approach seems to be strictly better than other.
958 targets: Vec<BasicBlock>,
961 /// Indicates that the landing pad is finished and unwinding should
962 /// continue. Emitted by build::scope::diverge_cleanup.
965 /// Indicates that the landing pad is finished and that the process
966 /// should abort. Used to prevent unwinding for foreign items.
969 /// Indicates a normal return. The return place should have
970 /// been filled in by now. This should occur at most once.
973 /// Indicates a terminator that can never be reached.
978 location: Place<'tcx>,
980 unwind: Option<BasicBlock>,
983 /// Drop the Place and assign the new value over it. This ensures
984 /// that the assignment to `P` occurs *even if* the destructor for
985 /// place unwinds. Its semantics are best explained by the
990 /// DropAndReplace(P <- V, goto BB1, unwind BB2)
998 /// Drop(P, goto BB1, unwind BB2)
1001 /// // P is now uninitialized
1005 /// // P is now uninitialized -- its dtor panicked
1010 location: Place<'tcx>,
1011 value: Operand<'tcx>,
1013 unwind: Option<BasicBlock>,
1016 /// Block ends with a call of a converging function
1018 /// The function that’s being called
1019 func: Operand<'tcx>,
1020 /// Arguments the function is called with.
1021 /// These are owned by the callee, which is free to modify them.
1022 /// This allows the memory occupied by "by-value" arguments to be
1023 /// reused across function calls without duplicating the contents.
1024 args: Vec<Operand<'tcx>>,
1025 /// Destination for the return value. If some, the call is converging.
1026 destination: Option<(Place<'tcx>, BasicBlock)>,
1027 /// Cleanups to be done if the call unwinds.
1028 cleanup: Option<BasicBlock>,
1031 /// Jump to the target if the condition has the expected value,
1032 /// otherwise panic with a message and a cleanup target.
1034 cond: Operand<'tcx>,
1036 msg: AssertMessage<'tcx>,
1038 cleanup: Option<BasicBlock>,
1043 /// The value to return
1044 value: Operand<'tcx>,
1045 /// Where to resume to
1047 /// Cleanup to be done if the generator is dropped at this suspend point
1048 drop: Option<BasicBlock>,
1051 /// Indicates the end of the dropping of a generator
1054 /// A block where control flow only ever takes one real path, but borrowck
1055 /// needs to be more conservative.
1057 /// The target normal control flow will take
1058 real_target: BasicBlock,
1059 /// The list of blocks control flow could conceptually take, but won't
1061 imaginary_targets: Vec<BasicBlock>,
1063 /// A terminator for blocks that only take one path in reality, but where we
1064 /// reserve the right to unwind in borrowck, even if it won't happen in practice.
1065 /// This can arise in infinite loops with no function calls for example.
1067 /// The target normal control flow will take
1068 real_target: BasicBlock,
1069 /// The imaginary cleanup block link. This particular path will never be taken
1070 /// in practice, but in order to avoid fragility we want to always
1071 /// consider it in borrowck. We don't want to accept programs which
1072 /// pass borrowck only when panic=abort or some assertions are disabled
1073 /// due to release vs. debug mode builds. This needs to be an Option because
1074 /// of the remove_noop_landing_pads and no_landing_pads passes
1075 unwind: Option<BasicBlock>,
1079 pub type Successors<'a> =
1080 iter::Chain<option::IntoIter<&'a BasicBlock>, slice::Iter<'a, BasicBlock>>;
1081 pub type SuccessorsMut<'a> =
1082 iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>;
1084 impl<'tcx> Terminator<'tcx> {
1085 pub fn successors(&self) -> Successors {
1086 self.kind.successors()
1089 pub fn successors_mut(&mut self) -> SuccessorsMut {
1090 self.kind.successors_mut()
1093 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1097 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1098 self.kind.unwind_mut()
1102 impl<'tcx> TerminatorKind<'tcx> {
1103 pub fn if_<'a, 'gcx>(
1104 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1105 cond: Operand<'tcx>,
1108 ) -> TerminatorKind<'tcx> {
1109 static BOOL_SWITCH_FALSE: &'static [u128] = &[0];
1110 TerminatorKind::SwitchInt {
1112 switch_ty: tcx.types.bool,
1113 values: From::from(BOOL_SWITCH_FALSE),
1114 targets: vec![f, t],
1118 pub fn successors(&self) -> Successors {
1119 use self::TerminatorKind::*;
1130 } => None.into_iter().chain(&[]),
1131 Goto { target: ref t }
1134 cleanup: Some(ref t),
1138 destination: Some((_, ref t)),
1165 } => Some(t).into_iter().chain(&[]),
1167 destination: Some((_, ref t)),
1168 cleanup: Some(ref u),
1178 unwind: Some(ref u),
1183 unwind: Some(ref u),
1188 cleanup: Some(ref u),
1193 unwind: Some(ref u),
1194 } => Some(t).into_iter().chain(slice::from_ref(u)),
1195 SwitchInt { ref targets, .. } => None.into_iter().chain(&targets[..]),
1198 ref imaginary_targets,
1199 } => Some(real_target).into_iter().chain(&imaginary_targets[..]),
1203 pub fn successors_mut(&mut self) -> SuccessorsMut {
1204 use self::TerminatorKind::*;
1215 } => None.into_iter().chain(&mut []),
1216 Goto { target: ref mut t }
1219 cleanup: Some(ref mut t),
1223 destination: Some((_, ref mut t)),
1248 real_target: ref mut t,
1250 } => Some(t).into_iter().chain(&mut []),
1252 destination: Some((_, ref mut t)),
1253 cleanup: Some(ref mut u),
1258 drop: Some(ref mut u),
1263 unwind: Some(ref mut u),
1268 unwind: Some(ref mut u),
1273 cleanup: Some(ref mut u),
1277 real_target: ref mut t,
1278 unwind: Some(ref mut u),
1279 } => Some(t).into_iter().chain(slice::from_mut(u)),
1282 } => None.into_iter().chain(&mut targets[..]),
1284 ref mut real_target,
1285 ref mut imaginary_targets,
1286 } => Some(real_target)
1288 .chain(&mut imaginary_targets[..]),
1292 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1294 TerminatorKind::Goto { .. }
1295 | TerminatorKind::Resume
1296 | TerminatorKind::Abort
1297 | TerminatorKind::Return
1298 | TerminatorKind::Unreachable
1299 | TerminatorKind::GeneratorDrop
1300 | TerminatorKind::Yield { .. }
1301 | TerminatorKind::SwitchInt { .. }
1302 | TerminatorKind::FalseEdges { .. } => None,
1303 TerminatorKind::Call {
1304 cleanup: ref unwind,
1307 | TerminatorKind::Assert {
1308 cleanup: ref unwind,
1311 | TerminatorKind::DropAndReplace { ref unwind, .. }
1312 | TerminatorKind::Drop { ref unwind, .. }
1313 | TerminatorKind::FalseUnwind { ref unwind, .. } => Some(unwind),
1317 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1319 TerminatorKind::Goto { .. }
1320 | TerminatorKind::Resume
1321 | TerminatorKind::Abort
1322 | TerminatorKind::Return
1323 | TerminatorKind::Unreachable
1324 | TerminatorKind::GeneratorDrop
1325 | TerminatorKind::Yield { .. }
1326 | TerminatorKind::SwitchInt { .. }
1327 | TerminatorKind::FalseEdges { .. } => None,
1328 TerminatorKind::Call {
1329 cleanup: ref mut unwind,
1332 | TerminatorKind::Assert {
1333 cleanup: ref mut unwind,
1336 | TerminatorKind::DropAndReplace { ref mut unwind, .. }
1337 | TerminatorKind::Drop { ref mut unwind, .. }
1338 | TerminatorKind::FalseUnwind { ref mut unwind, .. } => Some(unwind),
1343 impl<'tcx> BasicBlockData<'tcx> {
1344 pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
1352 /// Accessor for terminator.
1354 /// Terminator may not be None after construction of the basic block is complete. This accessor
1355 /// provides a convenience way to reach the terminator.
1356 pub fn terminator(&self) -> &Terminator<'tcx> {
1357 self.terminator.as_ref().expect("invalid terminator state")
1360 pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
1361 self.terminator.as_mut().expect("invalid terminator state")
1364 pub fn retain_statements<F>(&mut self, mut f: F)
1366 F: FnMut(&mut Statement) -> bool,
1368 for s in &mut self.statements {
1375 pub fn expand_statements<F, I>(&mut self, mut f: F)
1377 F: FnMut(&mut Statement<'tcx>) -> Option<I>,
1378 I: iter::TrustedLen<Item = Statement<'tcx>>,
1380 // Gather all the iterators we'll need to splice in, and their positions.
1381 let mut splices: Vec<(usize, I)> = vec![];
1382 let mut extra_stmts = 0;
1383 for (i, s) in self.statements.iter_mut().enumerate() {
1384 if let Some(mut new_stmts) = f(s) {
1385 if let Some(first) = new_stmts.next() {
1386 // We can already store the first new statement.
1389 // Save the other statements for optimized splicing.
1390 let remaining = new_stmts.size_hint().0;
1392 splices.push((i + 1 + extra_stmts, new_stmts));
1393 extra_stmts += remaining;
1401 // Splice in the new statements, from the end of the block.
1402 // FIXME(eddyb) This could be more efficient with a "gap buffer"
1403 // where a range of elements ("gap") is left uninitialized, with
1404 // splicing adding new elements to the end of that gap and moving
1405 // existing elements from before the gap to the end of the gap.
1406 // For now, this is safe code, emulating a gap but initializing it.
1407 let mut gap = self.statements.len()..self.statements.len() + extra_stmts;
1408 self.statements.resize(
1411 source_info: SourceInfo {
1413 scope: OUTERMOST_SOURCE_SCOPE,
1415 kind: StatementKind::Nop,
1418 for (splice_start, new_stmts) in splices.into_iter().rev() {
1419 let splice_end = splice_start + new_stmts.size_hint().0;
1420 while gap.end > splice_end {
1423 self.statements.swap(gap.start, gap.end);
1425 self.statements.splice(splice_start..splice_end, new_stmts);
1426 gap.end = splice_start;
1430 pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
1431 if index < self.statements.len() {
1432 &self.statements[index]
1439 impl<'tcx> Debug for TerminatorKind<'tcx> {
1440 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1441 self.fmt_head(fmt)?;
1442 let successor_count = self.successors().count();
1443 let labels = self.fmt_successor_labels();
1444 assert_eq!(successor_count, labels.len());
1446 match successor_count {
1449 1 => write!(fmt, " -> {:?}", self.successors().nth(0).unwrap()),
1452 write!(fmt, " -> [")?;
1453 for (i, target) in self.successors().enumerate() {
1457 write!(fmt, "{}: {:?}", labels[i], target)?;
1465 impl<'tcx> TerminatorKind<'tcx> {
1466 /// Write the "head" part of the terminator; that is, its name and the data it uses to pick the
1467 /// successor basic block, if any. The only information not included is the list of possible
1468 /// successors, which may be rendered differently between the text and the graphviz format.
1469 pub fn fmt_head<W: Write>(&self, fmt: &mut W) -> fmt::Result {
1470 use self::TerminatorKind::*;
1472 Goto { .. } => write!(fmt, "goto"),
1474 discr: ref place, ..
1475 } => write!(fmt, "switchInt({:?})", place),
1476 Return => write!(fmt, "return"),
1477 GeneratorDrop => write!(fmt, "generator_drop"),
1478 Resume => write!(fmt, "resume"),
1479 Abort => write!(fmt, "abort"),
1480 Yield { ref value, .. } => write!(fmt, "_1 = suspend({:?})", value),
1481 Unreachable => write!(fmt, "unreachable"),
1482 Drop { ref location, .. } => write!(fmt, "drop({:?})", location),
1487 } => write!(fmt, "replace({:?} <- {:?})", location, value),
1494 if let Some((ref destination, _)) = *destination {
1495 write!(fmt, "{:?} = ", destination)?;
1497 write!(fmt, "{:?}(", func)?;
1498 for (index, arg) in args.iter().enumerate() {
1502 write!(fmt, "{:?}", arg)?;
1512 write!(fmt, "assert(")?;
1516 write!(fmt, "{:?}, \"{:?}\")", cond, msg)
1518 FalseEdges { .. } => write!(fmt, "falseEdges"),
1519 FalseUnwind { .. } => write!(fmt, "falseUnwind"),
1523 /// Return the list of labels for the edges to the successor basic blocks.
1524 pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> {
1525 use self::TerminatorKind::*;
1527 Return | Resume | Abort | Unreachable | GeneratorDrop => vec![],
1528 Goto { .. } => vec!["".into()],
1534 let size = ty::tls::with(|tcx| {
1535 let param_env = ty::ParamEnv::empty();
1536 let switch_ty = tcx.lift_to_global(&switch_ty).unwrap();
1537 tcx.layout_of(param_env.and(switch_ty)).unwrap().size
1542 let mut s = String::new();
1544 val: ConstValue::Scalar(
1547 size: size.bytes() as u8,
1552 fmt_const_val(&mut s, &c).unwrap();
1554 }).chain(iter::once(String::from("otherwise").into()))
1558 destination: Some(_),
1561 } => vec!["return".into_cow(), "unwind".into_cow()],
1563 destination: Some(_),
1566 } => vec!["return".into_cow()],
1571 } => vec!["unwind".into_cow()],
1577 Yield { drop: Some(_), .. } => vec!["resume".into_cow(), "drop".into_cow()],
1578 Yield { drop: None, .. } => vec!["resume".into_cow()],
1579 DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => {
1580 vec!["return".into_cow()]
1587 } => vec!["return".into_cow(), "unwind".into_cow()],
1588 Assert { cleanup: None, .. } => vec!["".into()],
1589 Assert { .. } => vec!["success".into_cow(), "unwind".into_cow()],
1591 ref imaginary_targets,
1594 let mut l = vec!["real".into()];
1595 l.resize(imaginary_targets.len() + 1, "imaginary".into());
1600 } => vec!["real".into(), "cleanup".into()],
1601 FalseUnwind { unwind: None, .. } => vec!["real".into()],
1606 ///////////////////////////////////////////////////////////////////////////
1609 #[derive(Clone, RustcEncodable, RustcDecodable)]
1610 pub struct Statement<'tcx> {
1611 pub source_info: SourceInfo,
1612 pub kind: StatementKind<'tcx>,
1615 impl<'tcx> Statement<'tcx> {
1616 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
1617 /// invalidating statement indices in `Location`s.
1618 pub fn make_nop(&mut self) {
1619 self.kind = StatementKind::Nop
1622 /// Changes a statement to a nop and returns the original statement.
1623 pub fn replace_nop(&mut self) -> Self {
1625 source_info: self.source_info,
1626 kind: mem::replace(&mut self.kind, StatementKind::Nop),
1631 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1632 pub enum StatementKind<'tcx> {
1633 /// Write the RHS Rvalue to the LHS Place.
1634 Assign(Place<'tcx>, Rvalue<'tcx>),
1636 /// This represents all the reading that a pattern match may do
1637 /// (e.g. inspecting constants and discriminant values), and the
1638 /// kind of pattern it comes from. This is in order to adapt potential
1639 /// error messages to these specific patterns.
1640 FakeRead(FakeReadCause, Place<'tcx>),
1642 /// Write the discriminant for a variant to the enum Place.
1645 variant_index: usize,
1648 /// Start a live range for the storage of the local.
1651 /// End the current live range for the storage of the local.
1654 /// Execute a piece of inline Assembly.
1656 asm: Box<InlineAsm>,
1657 outputs: Vec<Place<'tcx>>,
1658 inputs: Vec<Operand<'tcx>>,
1661 /// Assert the given places to be valid inhabitants of their type. These statements are
1662 /// currently only interpreted by miri and only generated when "-Z mir-emit-validate" is passed.
1663 /// See <https://internals.rust-lang.org/t/types-as-contracts/5562/73> for more details.
1664 Validate(ValidationOp, Vec<ValidationOperand<'tcx, Place<'tcx>>>),
1666 /// Mark one terminating point of a region scope (i.e. static region).
1667 /// (The starting point(s) arise implicitly from borrows.)
1668 EndRegion(region::Scope),
1670 /// Encodes a user's type ascription. These need to be preserved
1671 /// intact so that NLL can respect them. For example:
1675 /// The effect of this annotation is to relate the type `T_y` of the place `y`
1676 /// to the user-given type `T`. The effect depends on the specified variance:
1678 /// - `Covariant` -- requires that `T_y <: T`
1679 /// - `Contravariant` -- requires that `T_y :> T`
1680 /// - `Invariant` -- requires that `T_y == T`
1681 /// - `Bivariant` -- no effect
1682 AscribeUserType(Place<'tcx>, ty::Variance, CanonicalTy<'tcx>),
1684 /// No-op. Useful for deleting instructions without affecting statement indices.
1688 /// The `FakeReadCause` describes the type of pattern why a `FakeRead` statement exists.
1689 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug)]
1690 pub enum FakeReadCause {
1691 /// Inject a fake read of the borrowed input at the start of each arm's
1692 /// pattern testing code.
1694 /// This should ensure that you cannot change the variant for an enum
1695 /// while you are in the midst of matching on it.
1698 /// Officially, the semantics of
1700 /// `let pattern = <expr>;`
1702 /// is that `<expr>` is evaluated into a temporary and then this temporary is
1703 /// into the pattern.
1705 /// However, if we see the simple pattern `let var = <expr>`, we optimize this to
1706 /// evaluate `<expr>` directly into the variable `var`. This is mostly unobservable,
1707 /// but in some cases it can affect the borrow checker, as in #53695.
1708 /// Therefore, we insert a "fake read" here to ensure that we get
1709 /// appropriate errors.
1713 /// The `ValidationOp` describes what happens with each of the operands of a
1714 /// `Validate` statement.
1715 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, PartialEq, Eq)]
1716 pub enum ValidationOp {
1717 /// Recursively traverse the place following the type and validate that all type
1718 /// invariants are maintained. Furthermore, acquire exclusive/read-only access to the
1719 /// memory reachable from the place.
1721 /// Recursive traverse the *mutable* part of the type and relinquish all exclusive
1724 /// Recursive traverse the *mutable* part of the type and relinquish all exclusive
1725 /// access *until* the given region ends. Then, access will be recovered.
1726 Suspend(region::Scope),
1729 impl Debug for ValidationOp {
1730 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1731 use self::ValidationOp::*;
1733 Acquire => write!(fmt, "Acquire"),
1734 Release => write!(fmt, "Release"),
1735 // (reuse lifetime rendering policy from ppaux.)
1736 Suspend(ref ce) => write!(fmt, "Suspend({})", ty::ReScope(*ce)),
1741 // This is generic so that it can be reused by miri
1742 #[derive(Clone, Hash, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1743 pub struct ValidationOperand<'tcx, T> {
1746 pub re: Option<region::Scope>,
1747 pub mutbl: hir::Mutability,
1750 impl<'tcx, T: Debug> Debug for ValidationOperand<'tcx, T> {
1751 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1752 write!(fmt, "{:?}: {:?}", self.place, self.ty)?;
1753 if let Some(ce) = self.re {
1754 // (reuse lifetime rendering policy from ppaux.)
1755 write!(fmt, "/{}", ty::ReScope(ce))?;
1757 if let hir::MutImmutable = self.mutbl {
1758 write!(fmt, " (imm)")?;
1764 impl<'tcx> Debug for Statement<'tcx> {
1765 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1766 use self::StatementKind::*;
1768 Assign(ref place, ref rv) => write!(fmt, "{:?} = {:?}", place, rv),
1769 FakeRead(ref cause, ref place) => write!(fmt, "FakeRead({:?}, {:?})", cause, place),
1770 // (reuse lifetime rendering policy from ppaux.)
1771 EndRegion(ref ce) => write!(fmt, "EndRegion({})", ty::ReScope(*ce)),
1772 Validate(ref op, ref places) => write!(fmt, "Validate({:?}, {:?})", op, places),
1773 StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place),
1774 StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place),
1778 } => write!(fmt, "discriminant({:?}) = {:?}", place, variant_index),
1783 } => write!(fmt, "asm!({:?} : {:?} : {:?})", asm, outputs, inputs),
1784 AscribeUserType(ref place, ref variance, ref c_ty) => {
1785 write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty)
1787 Nop => write!(fmt, "nop"),
1792 ///////////////////////////////////////////////////////////////////////////
1795 /// A path to a value; something that can be evaluated without
1796 /// changing or disturbing program state.
1797 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1798 pub enum Place<'tcx> {
1802 /// static or static mut variable
1803 Static(Box<Static<'tcx>>),
1805 /// Constant code promoted to an injected static
1806 Promoted(Box<(Promoted, Ty<'tcx>)>),
1808 /// projection out of a place (access a field, deref a pointer, etc)
1809 Projection(Box<PlaceProjection<'tcx>>),
1812 /// The def-id of a static, along with its normalized type (which is
1813 /// stored to avoid requiring normalization when reading MIR).
1814 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1815 pub struct Static<'tcx> {
1820 impl_stable_hash_for!(struct Static<'tcx> {
1825 /// The `Projection` data structure defines things of the form `B.x`
1826 /// or `*B` or `B[index]`. Note that it is parameterized because it is
1827 /// shared between `Constant` and `Place`. See the aliases
1828 /// `PlaceProjection` etc below.
1829 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1830 pub struct Projection<'tcx, B, V, T> {
1832 pub elem: ProjectionElem<'tcx, V, T>,
1835 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1836 pub enum ProjectionElem<'tcx, V, T> {
1841 /// These indices are generated by slice patterns. Easiest to explain
1845 /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
1846 /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
1847 /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
1848 /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
1851 /// index or -index (in Python terms), depending on from_end
1853 /// thing being indexed must be at least this long
1855 /// counting backwards from end?
1859 /// These indices are generated by slice patterns.
1861 /// slice[from:-to] in Python terms.
1867 /// "Downcast" to a variant of an ADT. Currently, we only introduce
1868 /// this for ADTs with more than one variant. It may be better to
1869 /// just introduce it always, or always for enums.
1870 Downcast(&'tcx AdtDef, usize),
1873 /// Alias for projections as they appear in places, where the base is a place
1874 /// and the index is a local.
1875 pub type PlaceProjection<'tcx> = Projection<'tcx, Place<'tcx>, Local, Ty<'tcx>>;
1877 /// Alias for projections as they appear in places, where the base is a place
1878 /// and the index is a local.
1879 pub type PlaceElem<'tcx> = ProjectionElem<'tcx, Local, Ty<'tcx>>;
1883 DEBUG_FORMAT = "field[{}]"
1887 impl<'tcx> Place<'tcx> {
1888 pub fn field(self, f: Field, ty: Ty<'tcx>) -> Place<'tcx> {
1889 self.elem(ProjectionElem::Field(f, ty))
1892 pub fn deref(self) -> Place<'tcx> {
1893 self.elem(ProjectionElem::Deref)
1896 pub fn downcast(self, adt_def: &'tcx AdtDef, variant_index: usize) -> Place<'tcx> {
1897 self.elem(ProjectionElem::Downcast(adt_def, variant_index))
1900 pub fn index(self, index: Local) -> Place<'tcx> {
1901 self.elem(ProjectionElem::Index(index))
1904 pub fn elem(self, elem: PlaceElem<'tcx>) -> Place<'tcx> {
1905 Place::Projection(Box::new(PlaceProjection { base: self, elem }))
1908 /// Find the innermost `Local` from this `Place`.
1909 pub fn local(&self) -> Option<Local> {
1911 Place::Local(local) |
1912 Place::Projection(box Projection {
1913 base: Place::Local(local),
1914 elem: ProjectionElem::Deref,
1921 impl<'tcx> Debug for Place<'tcx> {
1922 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1926 Local(id) => write!(fmt, "{:?}", id),
1927 Static(box self::Static { def_id, ty }) => write!(
1930 ty::tls::with(|tcx| tcx.item_path_str(def_id)),
1933 Promoted(ref promoted) => write!(fmt, "({:?}: {:?})", promoted.0, promoted.1),
1934 Projection(ref data) => match data.elem {
1935 ProjectionElem::Downcast(ref adt_def, index) => {
1936 write!(fmt, "({:?} as {})", data.base, adt_def.variants[index].name)
1938 ProjectionElem::Deref => write!(fmt, "(*{:?})", data.base),
1939 ProjectionElem::Field(field, ty) => {
1940 write!(fmt, "({:?}.{:?}: {:?})", data.base, field.index(), ty)
1942 ProjectionElem::Index(ref index) => write!(fmt, "{:?}[{:?}]", data.base, index),
1943 ProjectionElem::ConstantIndex {
1947 } => write!(fmt, "{:?}[{:?} of {:?}]", data.base, offset, min_length),
1948 ProjectionElem::ConstantIndex {
1952 } => write!(fmt, "{:?}[-{:?} of {:?}]", data.base, offset, min_length),
1953 ProjectionElem::Subslice { from, to } if to == 0 => {
1954 write!(fmt, "{:?}[{:?}:]", data.base, from)
1956 ProjectionElem::Subslice { from, to } if from == 0 => {
1957 write!(fmt, "{:?}[:-{:?}]", data.base, to)
1959 ProjectionElem::Subslice { from, to } => {
1960 write!(fmt, "{:?}[{:?}:-{:?}]", data.base, from, to)
1967 ///////////////////////////////////////////////////////////////////////////
1971 pub struct SourceScope {
1972 DEBUG_FORMAT = "scope[{}]",
1973 const OUTERMOST_SOURCE_SCOPE = 0,
1977 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1978 pub struct SourceScopeData {
1980 pub parent_scope: Option<SourceScope>,
1983 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1984 pub struct SourceScopeLocalData {
1985 /// A NodeId with lint levels equivalent to this scope's lint levels.
1986 pub lint_root: ast::NodeId,
1987 /// The unsafe block that contains this node.
1991 ///////////////////////////////////////////////////////////////////////////
1994 /// These are values that can appear inside an rvalue (or an index
1995 /// place). They are intentionally limited to prevent rvalues from
1996 /// being nested in one another.
1997 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
1998 pub enum Operand<'tcx> {
1999 /// Copy: The value must be available for use afterwards.
2001 /// This implies that the type of the place must be `Copy`; this is true
2002 /// by construction during build, but also checked by the MIR type checker.
2005 /// Move: The value (including old borrows of it) will not be used again.
2007 /// Safe for values of all types (modulo future developments towards `?Move`).
2008 /// Correct usage patterns are enforced by the borrow checker for safe code.
2009 /// `Copy` may be converted to `Move` to enable "last-use" optimizations.
2012 /// Synthesizes a constant value.
2013 Constant(Box<Constant<'tcx>>),
2016 impl<'tcx> Debug for Operand<'tcx> {
2017 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2018 use self::Operand::*;
2020 Constant(ref a) => write!(fmt, "{:?}", a),
2021 Copy(ref place) => write!(fmt, "{:?}", place),
2022 Move(ref place) => write!(fmt, "move {:?}", place),
2027 impl<'tcx> Operand<'tcx> {
2028 /// Convenience helper to make a constant that refers to the fn
2029 /// with given def-id and substs. Since this is used to synthesize
2030 /// MIR, assumes `user_ty` is None.
2031 pub fn function_handle<'a>(
2032 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2034 substs: &'tcx Substs<'tcx>,
2037 let ty = tcx.type_of(def_id).subst(tcx, substs);
2038 Operand::Constant(box Constant {
2042 literal: ty::Const::zero_sized(tcx, ty),
2046 pub fn to_copy(&self) -> Self {
2048 Operand::Copy(_) | Operand::Constant(_) => self.clone(),
2049 Operand::Move(ref place) => Operand::Copy(place.clone()),
2054 ///////////////////////////////////////////////////////////////////////////
2057 #[derive(Clone, RustcEncodable, RustcDecodable)]
2058 pub enum Rvalue<'tcx> {
2059 /// x (either a move or copy, depending on type of x)
2063 Repeat(Operand<'tcx>, u64),
2066 Ref(Region<'tcx>, BorrowKind, Place<'tcx>),
2068 /// length of a [X] or [X;n] value
2071 Cast(CastKind, Operand<'tcx>, Ty<'tcx>),
2073 BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
2074 CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
2076 NullaryOp(NullOp, Ty<'tcx>),
2077 UnaryOp(UnOp, Operand<'tcx>),
2079 /// Read the discriminant of an ADT.
2081 /// Undefined (i.e. no effort is made to make it defined, but there’s no reason why it cannot
2082 /// be defined to return, say, a 0) if ADT is not an enum.
2083 Discriminant(Place<'tcx>),
2085 /// Create an aggregate value, like a tuple or struct. This is
2086 /// only needed because we want to distinguish `dest = Foo { x:
2087 /// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case
2088 /// that `Foo` has a destructor. These rvalues can be optimized
2089 /// away after type-checking and before lowering.
2090 Aggregate(Box<AggregateKind<'tcx>>, Vec<Operand<'tcx>>),
2093 #[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2097 /// Convert unique, zero-sized type for a fn to fn()
2100 /// Convert non capturing closure to fn()
2103 /// Convert safe fn() to unsafe fn()
2106 /// "Unsize" -- convert a thin-or-fat pointer to a fat pointer.
2107 /// codegen must figure out the details once full monomorphization
2108 /// is known. For example, this could be used to cast from a
2109 /// `&[i32;N]` to a `&[i32]`, or a `Box<T>` to a `Box<Trait>`
2110 /// (presuming `T: Trait`).
2114 #[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2115 pub enum AggregateKind<'tcx> {
2116 /// The type is of the element
2120 /// The second field is the variant index. It's equal to 0 for struct
2121 /// and union expressions. The fourth field is
2122 /// active field number and is present only for union expressions
2123 /// -- e.g. for a union expression `SomeUnion { c: .. }`, the
2124 /// active field index would identity the field `c`
2129 Option<CanonicalTy<'tcx>>,
2133 Closure(DefId, ClosureSubsts<'tcx>),
2134 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
2137 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2139 /// The `+` operator (addition)
2141 /// The `-` operator (subtraction)
2143 /// The `*` operator (multiplication)
2145 /// The `/` operator (division)
2147 /// The `%` operator (modulus)
2149 /// The `^` operator (bitwise xor)
2151 /// The `&` operator (bitwise and)
2153 /// The `|` operator (bitwise or)
2155 /// The `<<` operator (shift left)
2157 /// The `>>` operator (shift right)
2159 /// The `==` operator (equality)
2161 /// The `<` operator (less than)
2163 /// The `<=` operator (less than or equal to)
2165 /// The `!=` operator (not equal to)
2167 /// The `>=` operator (greater than or equal to)
2169 /// The `>` operator (greater than)
2171 /// The `ptr.offset` operator
2176 pub fn is_checkable(self) -> bool {
2179 Add | Sub | Mul | Shl | Shr => true,
2185 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2187 /// Return the size of a value of that type
2189 /// Create a new uninitialized box for a value of that type
2193 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2195 /// The `!` operator for logical inversion
2197 /// The `-` operator for negation
2201 impl<'tcx> Debug for Rvalue<'tcx> {
2202 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2203 use self::Rvalue::*;
2206 Use(ref place) => write!(fmt, "{:?}", place),
2207 Repeat(ref a, ref b) => write!(fmt, "[{:?}; {:?}]", a, b),
2208 Len(ref a) => write!(fmt, "Len({:?})", a),
2209 Cast(ref kind, ref place, ref ty) => {
2210 write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind)
2212 BinaryOp(ref op, ref a, ref b) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
2213 CheckedBinaryOp(ref op, ref a, ref b) => {
2214 write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b)
2216 UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
2217 Discriminant(ref place) => write!(fmt, "discriminant({:?})", place),
2218 NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
2219 Ref(region, borrow_kind, ref place) => {
2220 let kind_str = match borrow_kind {
2221 BorrowKind::Shared => "",
2222 BorrowKind::Shallow => "shallow ",
2223 BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ",
2226 // When printing regions, add trailing space if necessary.
2227 let region = if ppaux::verbose() || ppaux::identify_regions() {
2228 let mut region = region.to_string();
2229 if region.len() > 0 {
2234 // Do not even print 'static
2237 write!(fmt, "&{}{}{:?}", region, kind_str, place)
2240 Aggregate(ref kind, ref places) => {
2241 fn fmt_tuple(fmt: &mut Formatter, places: &[Operand]) -> fmt::Result {
2242 let mut tuple_fmt = fmt.debug_tuple("");
2243 for place in places {
2244 tuple_fmt.field(place);
2250 AggregateKind::Array(_) => write!(fmt, "{:?}", places),
2252 AggregateKind::Tuple => match places.len() {
2253 0 => write!(fmt, "()"),
2254 1 => write!(fmt, "({:?},)", places[0]),
2255 _ => fmt_tuple(fmt, places),
2258 AggregateKind::Adt(adt_def, variant, substs, _user_ty, _) => {
2259 let variant_def = &adt_def.variants[variant];
2261 ppaux::parameterized(fmt, substs, variant_def.did, &[])?;
2263 match variant_def.ctor_kind {
2264 CtorKind::Const => Ok(()),
2265 CtorKind::Fn => fmt_tuple(fmt, places),
2266 CtorKind::Fictive => {
2267 let mut struct_fmt = fmt.debug_struct("");
2268 for (field, place) in variant_def.fields.iter().zip(places) {
2269 struct_fmt.field(&field.ident.as_str(), place);
2276 AggregateKind::Closure(def_id, _) => ty::tls::with(|tcx| {
2277 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2278 let name = if tcx.sess.opts.debugging_opts.span_free_formats {
2279 format!("[closure@{:?}]", node_id)
2281 format!("[closure@{:?}]", tcx.hir.span(node_id))
2283 let mut struct_fmt = fmt.debug_struct(&name);
2285 tcx.with_freevars(node_id, |freevars| {
2286 for (freevar, place) in freevars.iter().zip(places) {
2287 let var_name = tcx.hir.name(freevar.var_id());
2288 struct_fmt.field(&var_name.as_str(), place);
2294 write!(fmt, "[closure]")
2298 AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
2299 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2300 let name = format!("[generator@{:?}]", tcx.hir.span(node_id));
2301 let mut struct_fmt = fmt.debug_struct(&name);
2303 tcx.with_freevars(node_id, |freevars| {
2304 for (freevar, place) in freevars.iter().zip(places) {
2305 let var_name = tcx.hir.name(freevar.var_id());
2306 struct_fmt.field(&var_name.as_str(), place);
2308 struct_fmt.field("$state", &places[freevars.len()]);
2309 for i in (freevars.len() + 1)..places.len() {
2311 .field(&format!("${}", i - freevars.len() - 1), &places[i]);
2317 write!(fmt, "[generator]")
2326 ///////////////////////////////////////////////////////////////////////////
2329 /// Two constants are equal if they are the same constant. Note that
2330 /// this does not necessarily mean that they are "==" in Rust -- in
2331 /// particular one must be wary of `NaN`!
2333 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2334 pub struct Constant<'tcx> {
2338 /// Optional user-given type: for something like
2339 /// `collect::<Vec<_>>`, this would be present and would
2340 /// indicate that `Vec<_>` was explicitly specified.
2342 /// Needed for NLL to impose user-given type constraints.
2343 pub user_ty: Option<CanonicalTy<'tcx>>,
2345 pub literal: &'tcx ty::Const<'tcx>,
2349 pub struct Promoted {
2350 DEBUG_FORMAT = "promoted[{}]"
2354 impl<'tcx> Debug for Constant<'tcx> {
2355 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2356 write!(fmt, "const ")?;
2357 fmt_const_val(fmt, self.literal)
2361 /// Write a `ConstValue` in a way closer to the original source code than the `Debug` output.
2362 pub fn fmt_const_val(f: &mut impl Write, const_val: &ty::Const) -> fmt::Result {
2364 let value = const_val.val;
2365 let ty = const_val.ty;
2366 // print some primitives
2367 if let ConstValue::Scalar(Scalar::Bits { bits, .. }) = value {
2369 Bool if bits == 0 => return write!(f, "false"),
2370 Bool if bits == 1 => return write!(f, "true"),
2371 Float(ast::FloatTy::F32) => return write!(f, "{}f32", Single::from_bits(bits)),
2372 Float(ast::FloatTy::F64) => return write!(f, "{}f64", Double::from_bits(bits)),
2373 Uint(ui) => return write!(f, "{:?}{}", bits, ui),
2375 let bit_width = ty::tls::with(|tcx| {
2376 let ty = tcx.lift_to_global(&ty).unwrap();
2377 tcx.layout_of(ty::ParamEnv::empty().and(ty))
2382 let shift = 128 - bit_width;
2383 return write!(f, "{:?}{}", ((bits as i128) << shift) >> shift, i);
2385 Char => return write!(f, "{:?}", ::std::char::from_u32(bits as u32).unwrap()),
2389 // print function definitons
2390 if let FnDef(did, _) = ty.sty {
2391 return write!(f, "{}", item_path_str(did));
2393 // print string literals
2394 if let ConstValue::ScalarPair(ptr, len) = value {
2395 if let Scalar::Ptr(ptr) = ptr {
2396 if let ScalarMaybeUndef::Scalar(Scalar::Bits { bits: len, .. }) = len {
2397 if let Ref(_, &ty::TyS { sty: Str, .. }, _) = ty.sty {
2398 return ty::tls::with(|tcx| {
2399 let alloc = tcx.alloc_map.lock().get(ptr.alloc_id);
2400 if let Some(interpret::AllocType::Memory(alloc)) = alloc {
2401 assert_eq!(len as usize as u128, len);
2403 &alloc.bytes[(ptr.offset.bytes() as usize)..][..(len as usize)];
2404 let s = ::std::str::from_utf8(slice).expect("non utf8 str from miri");
2405 write!(f, "{:?}", s)
2407 write!(f, "pointer to erroneous constant {:?}, {:?}", ptr, len)
2414 // just raw dump everything else
2415 write!(f, "{:?}:{}", value, ty)
2418 fn item_path_str(def_id: DefId) -> String {
2419 ty::tls::with(|tcx| tcx.item_path_str(def_id))
2422 impl<'tcx> graph::DirectedGraph for Mir<'tcx> {
2423 type Node = BasicBlock;
2426 impl<'tcx> graph::WithNumNodes for Mir<'tcx> {
2427 fn num_nodes(&self) -> usize {
2428 self.basic_blocks.len()
2432 impl<'tcx> graph::WithStartNode for Mir<'tcx> {
2433 fn start_node(&self) -> Self::Node {
2438 impl<'tcx> graph::WithPredecessors for Mir<'tcx> {
2439 fn predecessors<'graph>(
2442 ) -> <Self as GraphPredecessors<'graph>>::Iter {
2443 self.predecessors_for(node).clone().into_iter()
2447 impl<'tcx> graph::WithSuccessors for Mir<'tcx> {
2448 fn successors<'graph>(
2451 ) -> <Self as GraphSuccessors<'graph>>::Iter {
2452 self.basic_blocks[node].terminator().successors().cloned()
2456 impl<'a, 'b> graph::GraphPredecessors<'b> for Mir<'a> {
2457 type Item = BasicBlock;
2458 type Iter = IntoIter<BasicBlock>;
2461 impl<'a, 'b> graph::GraphSuccessors<'b> for Mir<'a> {
2462 type Item = BasicBlock;
2463 type Iter = iter::Cloned<Successors<'b>>;
2466 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
2467 pub struct Location {
2468 /// the location is within this block
2469 pub block: BasicBlock,
2471 /// the location is the start of the statement; or, if `statement_index`
2472 /// == num-statements, then the start of the terminator.
2473 pub statement_index: usize,
2476 impl fmt::Debug for Location {
2477 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
2478 write!(fmt, "{:?}[{}]", self.block, self.statement_index)
2483 pub const START: Location = Location {
2488 /// Returns the location immediately after this one within the enclosing block.
2490 /// Note that if this location represents a terminator, then the
2491 /// resulting location would be out of bounds and invalid.
2492 pub fn successor_within_block(&self) -> Location {
2495 statement_index: self.statement_index + 1,
2499 pub fn dominates(&self, other: Location, dominators: &Dominators<BasicBlock>) -> bool {
2500 if self.block == other.block {
2501 self.statement_index <= other.statement_index
2503 dominators.is_dominated_by(other.block, self.block)
2508 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2509 pub enum UnsafetyViolationKind {
2511 /// unsafety is not allowed at all in min const fn
2513 ExternStatic(ast::NodeId),
2514 BorrowPacked(ast::NodeId),
2517 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2518 pub struct UnsafetyViolation {
2519 pub source_info: SourceInfo,
2520 pub description: InternedString,
2521 pub details: InternedString,
2522 pub kind: UnsafetyViolationKind,
2525 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2526 pub struct UnsafetyCheckResult {
2527 /// Violations that are propagated *upwards* from this function
2528 pub violations: Lrc<[UnsafetyViolation]>,
2529 /// unsafe blocks in this function, along with whether they are used. This is
2530 /// used for the "unused_unsafe" lint.
2531 pub unsafe_blocks: Lrc<[(ast::NodeId, bool)]>,
2534 /// The layout of generator state
2535 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2536 pub struct GeneratorLayout<'tcx> {
2537 pub fields: Vec<LocalDecl<'tcx>>,
2540 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2541 pub struct BorrowCheckResult<'gcx> {
2542 pub closure_requirements: Option<ClosureRegionRequirements<'gcx>>,
2543 pub used_mut_upvars: SmallVec<[Field; 8]>,
2546 /// After we borrow check a closure, we are left with various
2547 /// requirements that we have inferred between the free regions that
2548 /// appear in the closure's signature or on its field types. These
2549 /// requirements are then verified and proved by the closure's
2550 /// creating function. This struct encodes those requirements.
2552 /// The requirements are listed as being between various
2553 /// `RegionVid`. The 0th region refers to `'static`; subsequent region
2554 /// vids refer to the free regions that appear in the closure (or
2555 /// generator's) type, in order of appearance. (This numbering is
2556 /// actually defined by the `UniversalRegions` struct in the NLL
2557 /// region checker. See for example
2558 /// `UniversalRegions::closure_mapping`.) Note that we treat the free
2559 /// regions in the closure's type "as if" they were erased, so their
2560 /// precise identity is not important, only their position.
2562 /// Example: If type check produces a closure with the closure substs:
2565 /// ClosureSubsts = [
2566 /// i8, // the "closure kind"
2567 /// for<'x> fn(&'a &'x u32) -> &'x u32, // the "closure signature"
2568 /// &'a String, // some upvar
2572 /// here, there is one unique free region (`'a`) but it appears
2573 /// twice. We would "renumber" each occurrence to a unique vid, as follows:
2576 /// ClosureSubsts = [
2577 /// i8, // the "closure kind"
2578 /// for<'x> fn(&'1 &'x u32) -> &'x u32, // the "closure signature"
2579 /// &'2 String, // some upvar
2583 /// Now the code might impose a requirement like `'1: '2`. When an
2584 /// instance of the closure is created, the corresponding free regions
2585 /// can be extracted from its type and constrained to have the given
2586 /// outlives relationship.
2588 /// In some cases, we have to record outlives requirements between
2589 /// types and regions as well. In that case, if those types include
2590 /// any regions, those regions are recorded as `ReClosureBound`
2591 /// instances assigned one of these same indices. Those regions will
2592 /// be substituted away by the creator. We use `ReClosureBound` in
2593 /// that case because the regions must be allocated in the global
2594 /// TyCtxt, and hence we cannot use `ReVar` (which is what we use
2595 /// internally within the rest of the NLL code).
2596 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2597 pub struct ClosureRegionRequirements<'gcx> {
2598 /// The number of external regions defined on the closure. In our
2599 /// example above, it would be 3 -- one for `'static`, then `'1`
2600 /// and `'2`. This is just used for a sanity check later on, to
2601 /// make sure that the number of regions we see at the callsite
2603 pub num_external_vids: usize,
2605 /// Requirements between the various free regions defined in
2607 pub outlives_requirements: Vec<ClosureOutlivesRequirement<'gcx>>,
2610 /// Indicates an outlives constraint between a type or between two
2611 /// free-regions declared on the closure.
2612 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2613 pub struct ClosureOutlivesRequirement<'tcx> {
2614 // This region or type ...
2615 pub subject: ClosureOutlivesSubject<'tcx>,
2617 // .. must outlive this one.
2618 pub outlived_free_region: ty::RegionVid,
2620 // If not, report an error here.
2621 pub blame_span: Span,
2624 /// The subject of a ClosureOutlivesRequirement -- that is, the thing
2625 /// that must outlive some region.
2626 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2627 pub enum ClosureOutlivesSubject<'tcx> {
2628 /// Subject is a type, typically a type parameter, but could also
2629 /// be a projection. Indicates a requirement like `T: 'a` being
2630 /// passed to the caller, where the type here is `T`.
2632 /// The type here is guaranteed not to contain any free regions at
2636 /// Subject is a free region from the closure. Indicates a requirement
2637 /// like `'a: 'b` being passed to the caller; the region here is `'a`.
2638 Region(ty::RegionVid),
2642 * TypeFoldable implementations for MIR types
2645 CloneTypeFoldableAndLiftImpls! {
2653 SourceScopeLocalData,
2656 BraceStructTypeFoldableImpl! {
2657 impl<'tcx> TypeFoldable<'tcx> for Mir<'tcx> {
2660 source_scope_local_data,
2674 BraceStructTypeFoldableImpl! {
2675 impl<'tcx> TypeFoldable<'tcx> for GeneratorLayout<'tcx> {
2680 BraceStructTypeFoldableImpl! {
2681 impl<'tcx> TypeFoldable<'tcx> for LocalDecl<'tcx> {
2693 BraceStructTypeFoldableImpl! {
2694 impl<'tcx> TypeFoldable<'tcx> for BasicBlockData<'tcx> {
2701 BraceStructTypeFoldableImpl! {
2702 impl<'tcx> TypeFoldable<'tcx> for ValidationOperand<'tcx, Place<'tcx>> {
2703 place, ty, re, mutbl
2707 BraceStructTypeFoldableImpl! {
2708 impl<'tcx> TypeFoldable<'tcx> for Statement<'tcx> {
2713 EnumTypeFoldableImpl! {
2714 impl<'tcx> TypeFoldable<'tcx> for StatementKind<'tcx> {
2715 (StatementKind::Assign)(a, b),
2716 (StatementKind::FakeRead)(cause, place),
2717 (StatementKind::SetDiscriminant) { place, variant_index },
2718 (StatementKind::StorageLive)(a),
2719 (StatementKind::StorageDead)(a),
2720 (StatementKind::InlineAsm) { asm, outputs, inputs },
2721 (StatementKind::Validate)(a, b),
2722 (StatementKind::EndRegion)(a),
2723 (StatementKind::AscribeUserType)(a, v, b),
2724 (StatementKind::Nop),
2728 EnumTypeFoldableImpl! {
2729 impl<'tcx, T> TypeFoldable<'tcx> for ClearCrossCrate<T> {
2730 (ClearCrossCrate::Clear),
2731 (ClearCrossCrate::Set)(a),
2732 } where T: TypeFoldable<'tcx>
2735 impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
2736 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2737 use mir::TerminatorKind::*;
2739 let kind = match self.kind {
2740 Goto { target } => Goto { target: target },
2747 discr: discr.fold_with(folder),
2748 switch_ty: switch_ty.fold_with(folder),
2749 values: values.clone(),
2750 targets: targets.clone(),
2757 location: location.fold_with(folder),
2766 } => DropAndReplace {
2767 location: location.fold_with(folder),
2768 value: value.fold_with(folder),
2777 value: value.fold_with(folder),
2787 let dest = destination
2789 .map(|&(ref loc, dest)| (loc.fold_with(folder), dest));
2792 func: func.fold_with(folder),
2793 args: args.fold_with(folder),
2805 let msg = if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
2806 EvalErrorKind::BoundsCheck {
2807 len: len.fold_with(folder),
2808 index: index.fold_with(folder),
2814 cond: cond.fold_with(folder),
2821 GeneratorDrop => GeneratorDrop,
2825 Unreachable => Unreachable,
2828 ref imaginary_targets,
2831 imaginary_targets: imaginary_targets.clone(),
2842 source_info: self.source_info,
2847 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2848 use mir::TerminatorKind::*;
2855 } => discr.visit_with(visitor) || switch_ty.visit_with(visitor),
2856 Drop { ref location, .. } => location.visit_with(visitor),
2861 } => location.visit_with(visitor) || value.visit_with(visitor),
2862 Yield { ref value, .. } => value.visit_with(visitor),
2869 let dest = if let Some((ref loc, _)) = *destination {
2870 loc.visit_with(visitor)
2874 dest || func.visit_with(visitor) || args.visit_with(visitor)
2877 ref cond, ref msg, ..
2879 if cond.visit_with(visitor) {
2880 if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
2881 len.visit_with(visitor) || index.visit_with(visitor)
2896 | FalseUnwind { .. } => false,
2901 impl<'tcx> TypeFoldable<'tcx> for Place<'tcx> {
2902 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2904 &Place::Projection(ref p) => Place::Projection(p.fold_with(folder)),
2909 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2910 if let &Place::Projection(ref p) = self {
2911 p.visit_with(visitor)
2918 impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
2919 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2922 Use(ref op) => Use(op.fold_with(folder)),
2923 Repeat(ref op, len) => Repeat(op.fold_with(folder), len),
2924 Ref(region, bk, ref place) => {
2925 Ref(region.fold_with(folder), bk, place.fold_with(folder))
2927 Len(ref place) => Len(place.fold_with(folder)),
2928 Cast(kind, ref op, ty) => Cast(kind, op.fold_with(folder), ty.fold_with(folder)),
2929 BinaryOp(op, ref rhs, ref lhs) => {
2930 BinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
2932 CheckedBinaryOp(op, ref rhs, ref lhs) => {
2933 CheckedBinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
2935 UnaryOp(op, ref val) => UnaryOp(op, val.fold_with(folder)),
2936 Discriminant(ref place) => Discriminant(place.fold_with(folder)),
2937 NullaryOp(op, ty) => NullaryOp(op, ty.fold_with(folder)),
2938 Aggregate(ref kind, ref fields) => {
2939 let kind = box match **kind {
2940 AggregateKind::Array(ty) => AggregateKind::Array(ty.fold_with(folder)),
2941 AggregateKind::Tuple => AggregateKind::Tuple,
2942 AggregateKind::Adt(def, v, substs, user_ty, n) => AggregateKind::Adt(
2945 substs.fold_with(folder),
2946 user_ty.fold_with(folder),
2949 AggregateKind::Closure(id, substs) => {
2950 AggregateKind::Closure(id, substs.fold_with(folder))
2952 AggregateKind::Generator(id, substs, movablity) => {
2953 AggregateKind::Generator(id, substs.fold_with(folder), movablity)
2956 Aggregate(kind, fields.fold_with(folder))
2961 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2964 Use(ref op) => op.visit_with(visitor),
2965 Repeat(ref op, _) => op.visit_with(visitor),
2966 Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor),
2967 Len(ref place) => place.visit_with(visitor),
2968 Cast(_, ref op, ty) => op.visit_with(visitor) || ty.visit_with(visitor),
2969 BinaryOp(_, ref rhs, ref lhs) | CheckedBinaryOp(_, ref rhs, ref lhs) => {
2970 rhs.visit_with(visitor) || lhs.visit_with(visitor)
2972 UnaryOp(_, ref val) => val.visit_with(visitor),
2973 Discriminant(ref place) => place.visit_with(visitor),
2974 NullaryOp(_, ty) => ty.visit_with(visitor),
2975 Aggregate(ref kind, ref fields) => {
2977 AggregateKind::Array(ty) => ty.visit_with(visitor),
2978 AggregateKind::Tuple => false,
2979 AggregateKind::Adt(_, _, substs, user_ty, _) => {
2980 substs.visit_with(visitor) || user_ty.visit_with(visitor)
2982 AggregateKind::Closure(_, substs) => substs.visit_with(visitor),
2983 AggregateKind::Generator(_, substs, _) => substs.visit_with(visitor),
2984 }) || fields.visit_with(visitor)
2990 impl<'tcx> TypeFoldable<'tcx> for Operand<'tcx> {
2991 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2993 Operand::Copy(ref place) => Operand::Copy(place.fold_with(folder)),
2994 Operand::Move(ref place) => Operand::Move(place.fold_with(folder)),
2995 Operand::Constant(ref c) => Operand::Constant(c.fold_with(folder)),
2999 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
3001 Operand::Copy(ref place) | Operand::Move(ref place) => place.visit_with(visitor),
3002 Operand::Constant(ref c) => c.visit_with(visitor),
3007 impl<'tcx, B, V, T> TypeFoldable<'tcx> for Projection<'tcx, B, V, T>
3009 B: TypeFoldable<'tcx>,
3010 V: TypeFoldable<'tcx>,
3011 T: TypeFoldable<'tcx>,
3013 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3014 use mir::ProjectionElem::*;
3016 let base = self.base.fold_with(folder);
3017 let elem = match self.elem {
3019 Field(f, ref ty) => Field(f, ty.fold_with(folder)),
3020 Index(ref v) => Index(v.fold_with(folder)),
3021 ref elem => elem.clone(),
3024 Projection { base, elem }
3027 fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool {
3028 use mir::ProjectionElem::*;
3030 self.base.visit_with(visitor) || match self.elem {
3031 Field(_, ref ty) => ty.visit_with(visitor),
3032 Index(ref v) => v.visit_with(visitor),
3038 impl<'tcx> TypeFoldable<'tcx> for Field {
3039 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _: &mut F) -> Self {
3042 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
3047 impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> {
3048 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3050 span: self.span.clone(),
3051 ty: self.ty.fold_with(folder),
3052 user_ty: self.user_ty.fold_with(folder),
3053 literal: self.literal.fold_with(folder),
3056 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
3057 self.ty.visit_with(visitor) || self.literal.visit_with(visitor)