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::{EvalErrorKind, Scalar, Value};
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::small_vec::SmallVec;
28 use rustc_data_structures::sync::Lrc;
29 use rustc_data_structures::sync::ReadGuard;
30 use rustc_serialize as serialize;
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 /// where execution begins
135 pub const START_BLOCK: BasicBlock = BasicBlock(0);
137 impl<'tcx> Mir<'tcx> {
139 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
140 source_scopes: IndexVec<SourceScope, SourceScopeData>,
141 source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
142 promoted: IndexVec<Promoted, Mir<'tcx>>,
143 yield_ty: Option<Ty<'tcx>>,
144 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
146 upvar_decls: Vec<UpvarDecl>,
149 // We need `arg_count` locals, and one for the return place
151 local_decls.len() >= arg_count + 1,
152 "expected at least {} locals, got {}",
160 source_scope_local_data,
163 generator_drop: None,
164 generator_layout: None,
170 cache: cache::Cache::new(),
175 pub fn basic_blocks(&self) -> &IndexVec<BasicBlock, BasicBlockData<'tcx>> {
180 pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
181 self.cache.invalidate();
182 &mut self.basic_blocks
186 pub fn basic_blocks_and_local_decls_mut(
189 &mut IndexVec<BasicBlock, BasicBlockData<'tcx>>,
190 &mut LocalDecls<'tcx>,
192 self.cache.invalidate();
193 (&mut self.basic_blocks, &mut self.local_decls)
197 pub fn predecessors(&self) -> ReadGuard<IndexVec<BasicBlock, Vec<BasicBlock>>> {
198 self.cache.predecessors(self)
202 pub fn predecessors_for(&self, bb: BasicBlock) -> ReadGuard<Vec<BasicBlock>> {
203 ReadGuard::map(self.predecessors(), |p| &p[bb])
207 pub fn dominators(&self) -> Dominators<BasicBlock> {
212 pub fn local_kind(&self, local: Local) -> LocalKind {
213 let index = local.0 as usize;
216 self.local_decls[local].mutability == Mutability::Mut,
217 "return place should be mutable"
220 LocalKind::ReturnPointer
221 } else if index < self.arg_count + 1 {
223 } else if self.local_decls[local].name.is_some() {
227 self.local_decls[local].mutability == Mutability::Mut,
228 "temp should be mutable"
235 /// Returns an iterator over all temporaries.
237 pub fn temps_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
238 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
239 let local = Local::new(index);
240 if self.local_decls[local].is_user_variable.is_some() {
248 /// Returns an iterator over all user-declared locals.
250 pub fn vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
251 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
252 let local = Local::new(index);
253 if self.local_decls[local].is_user_variable.is_some() {
261 /// Returns an iterator over all user-declared mutable arguments and locals.
263 pub fn mut_vars_and_args_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
264 (1..self.local_decls.len()).filter_map(move |index| {
265 let local = Local::new(index);
266 let decl = &self.local_decls[local];
267 if (decl.is_user_variable.is_some() || index < self.arg_count + 1)
268 && decl.mutability == Mutability::Mut
277 /// Returns an iterator over all function arguments.
279 pub fn args_iter(&self) -> impl Iterator<Item = Local> {
280 let arg_count = self.arg_count;
281 (1..arg_count + 1).map(Local::new)
284 /// Returns an iterator over all user-defined variables and compiler-generated temporaries (all
285 /// locals that are neither arguments nor the return place).
287 pub fn vars_and_temps_iter(&self) -> impl Iterator<Item = Local> {
288 let arg_count = self.arg_count;
289 let local_count = self.local_decls.len();
290 (arg_count + 1..local_count).map(Local::new)
293 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
294 /// invalidating statement indices in `Location`s.
295 pub fn make_statement_nop(&mut self, location: Location) {
296 let block = &mut self[location.block];
297 debug_assert!(location.statement_index < block.statements.len());
298 block.statements[location.statement_index].make_nop()
301 /// Returns the source info associated with `location`.
302 pub fn source_info(&self, location: Location) -> &SourceInfo {
303 let block = &self[location.block];
304 let stmts = &block.statements;
305 let idx = location.statement_index;
306 if idx < stmts.len() {
307 &stmts[idx].source_info
309 assert!(idx == stmts.len());
310 &block.terminator().source_info
314 /// Check if `sub` is a sub scope of `sup`
315 pub fn is_sub_scope(&self, mut sub: SourceScope, sup: SourceScope) -> bool {
320 match self.source_scopes[sub].parent_scope {
321 None => return false,
327 /// Return the return type, it always return first element from `local_decls` array
328 pub fn return_ty(&self) -> Ty<'tcx> {
329 self.local_decls[RETURN_PLACE].ty
333 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
336 /// Unsafe because of a PushUnsafeBlock
338 /// Unsafe because of an unsafe fn
340 /// Unsafe because of an `unsafe` block
341 ExplicitUnsafe(ast::NodeId),
344 impl_stable_hash_for!(struct Mir<'tcx> {
347 source_scope_local_data,
360 impl<'tcx> Index<BasicBlock> for Mir<'tcx> {
361 type Output = BasicBlockData<'tcx>;
364 fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
365 &self.basic_blocks()[index]
369 impl<'tcx> IndexMut<BasicBlock> for Mir<'tcx> {
371 fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> {
372 &mut self.basic_blocks_mut()[index]
376 #[derive(Copy, Clone, Debug)]
377 pub enum ClearCrossCrate<T> {
382 impl<T> ClearCrossCrate<T> {
383 pub fn assert_crate_local(self) -> T {
385 ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"),
386 ClearCrossCrate::Set(v) => v,
391 impl<T: serialize::Encodable> serialize::UseSpecializedEncodable for ClearCrossCrate<T> {}
392 impl<T: serialize::Decodable> serialize::UseSpecializedDecodable for ClearCrossCrate<T> {}
394 /// Grouped information about the source code origin of a MIR entity.
395 /// Intended to be inspected by diagnostics and debuginfo.
396 /// Most passes can work with it as a whole, within a single function.
397 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
398 pub struct SourceInfo {
399 /// Source span for the AST pertaining to this MIR entity.
402 /// The source scope, keeping track of which bindings can be
403 /// seen by debuginfo, active lint levels, `unsafe {...}`, etc.
404 pub scope: SourceScope,
407 ///////////////////////////////////////////////////////////////////////////
408 // Mutability and borrow kinds
410 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
411 pub enum Mutability {
416 impl From<Mutability> for hir::Mutability {
417 fn from(m: Mutability) -> Self {
419 Mutability::Mut => hir::MutMutable,
420 Mutability::Not => hir::MutImmutable,
425 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
426 pub enum BorrowKind {
427 /// Data must be immutable and is aliasable.
430 /// Data must be immutable but not aliasable. This kind of borrow
431 /// cannot currently be expressed by the user and is used only in
432 /// implicit closure bindings. It is needed when you the closure
433 /// is borrowing or mutating a mutable referent, e.g.:
435 /// let x: &mut isize = ...;
436 /// let y = || *x += 5;
438 /// If we were to try to translate this closure into a more explicit
439 /// form, we'd encounter an error with the code as written:
441 /// struct Env { x: & &mut isize }
442 /// let x: &mut isize = ...;
443 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
444 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
446 /// This is then illegal because you cannot mutate a `&mut` found
447 /// in an aliasable location. To solve, you'd have to translate with
448 /// an `&mut` borrow:
450 /// struct Env { x: & &mut isize }
451 /// let x: &mut isize = ...;
452 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
453 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
455 /// Now the assignment to `**env.x` is legal, but creating a
456 /// mutable pointer to `x` is not because `x` is not mutable. We
457 /// could fix this by declaring `x` as `let mut x`. This is ok in
458 /// user code, if awkward, but extra weird for closures, since the
459 /// borrow is hidden.
461 /// So we introduce a "unique imm" borrow -- the referent is
462 /// immutable, but not aliasable. This solves the problem. For
463 /// simplicity, we don't give users the way to express this
464 /// borrow, it's just used when translating closures.
467 /// Data is mutable and not aliasable.
469 /// True if this borrow arose from method-call auto-ref
470 /// (i.e. `adjustment::Adjust::Borrow`)
471 allow_two_phase_borrow: bool,
476 pub fn allows_two_phase_borrow(&self) -> bool {
478 BorrowKind::Shared | BorrowKind::Unique => false,
480 allow_two_phase_borrow,
481 } => allow_two_phase_borrow,
486 ///////////////////////////////////////////////////////////////////////////
487 // Variables and temps
491 DEBUG_FORMAT = "_{}",
492 const RETURN_PLACE = 0,
495 /// Classifies locals into categories. See `Mir::local_kind`.
496 #[derive(PartialEq, Eq, Debug)]
498 /// User-declared variable binding
500 /// Compiler-introduced temporary
502 /// Function argument
504 /// Location of function's return value
508 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
509 pub struct VarBindingForm<'tcx> {
510 /// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`?
511 pub binding_mode: ty::BindingMode,
512 /// If an explicit type was provided for this variable binding,
513 /// this holds the source Span of that type.
515 /// NOTE: If you want to change this to a `HirId`, be wary that
516 /// doing so breaks incremental compilation (as of this writing),
517 /// while a `Span` does not cause our tests to fail.
518 pub opt_ty_info: Option<Span>,
519 /// Place of the RHS of the =, or the subject of the `match` where this
520 /// variable is initialized. None in the case of `let PATTERN;`.
521 /// Some((None, ..)) in the case of and `let [mut] x = ...` because
522 /// (a) the right-hand side isn't evaluated as a place expression.
523 /// (b) it gives a way to separate this case from the remaining cases
525 pub opt_match_place: Option<(Option<Place<'tcx>>, Span)>,
528 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
529 pub enum BindingForm<'tcx> {
530 /// This is a binding for a non-`self` binding, or a `self` that has an explicit type.
531 Var(VarBindingForm<'tcx>),
532 /// Binding for a `self`/`&self`/`&mut self` binding where the type is implicit.
536 CloneTypeFoldableAndLiftImpls! { BindingForm<'tcx>, }
538 impl_stable_hash_for!(struct self::VarBindingForm<'tcx> {
544 mod binding_form_impl {
545 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableHasherResult};
546 use ich::StableHashingContext;
548 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
549 fn hash_stable<W: StableHasherResult>(&self,
550 hcx: &mut StableHashingContext<'a>,
551 hasher: &mut StableHasher<W>) {
552 use super::BindingForm::*;
553 ::std::mem::discriminant(self).hash_stable(hcx, hasher);
556 Var(binding) => binding.hash_stable(hcx, hasher),
565 /// This can be a binding declared by the user, a temporary inserted by the compiler, a function
566 /// argument, or the return place.
567 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
568 pub struct LocalDecl<'tcx> {
569 /// `let mut x` vs `let x`.
571 /// Temporaries and the return place are always mutable.
572 pub mutability: Mutability,
574 /// Some(binding_mode) if this corresponds to a user-declared local variable.
576 /// This is solely used for local diagnostics when generating
577 /// warnings/errors when compiling the current crate, and
578 /// therefore it need not be visible across crates. pnkfelix
579 /// currently hypothesized we *need* to wrap this in a
580 /// `ClearCrossCrate` as long as it carries as `HirId`.
581 pub is_user_variable: Option<ClearCrossCrate<BindingForm<'tcx>>>,
583 /// True if this is an internal local
585 /// These locals are not based on types in the source code and are only used
586 /// for a few desugarings at the moment.
588 /// The generator transformation will sanity check the locals which are live
589 /// across a suspension point against the type components of the generator
590 /// which type checking knows are live across a suspension point. We need to
591 /// flag drop flags to avoid triggering this check as they are introduced
594 /// Unsafety checking will also ignore dereferences of these locals,
595 /// so they can be used for raw pointers only used in a desugaring.
597 /// This should be sound because the drop flags are fully algebraic, and
598 /// therefore don't affect the OIBIT or outlives properties of the
602 /// Type of this local.
605 /// Name of the local, used in debuginfo and pretty-printing.
607 /// Note that function arguments can also have this set to `Some(_)`
608 /// to generate better debuginfo.
609 pub name: Option<Name>,
611 /// The *syntactic* (i.e. not visibility) source scope the local is defined
612 /// in. If the local was defined in a let-statement, this
613 /// is *within* the let-statement, rather than outside
616 /// This is needed because the visibility source scope of locals within
617 /// a let-statement is weird.
619 /// The reason is that we want the local to be *within* the let-statement
620 /// for lint purposes, but we want the local to be *after* the let-statement
621 /// for names-in-scope purposes.
623 /// That's it, if we have a let-statement like the one in this
627 /// fn foo(x: &str) {
628 /// #[allow(unused_mut)]
629 /// let mut x: u32 = { // <- one unused mut
630 /// let mut y: u32 = x.parse().unwrap();
637 /// Then, from a lint point of view, the declaration of `x: u32`
638 /// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the
639 /// lint scopes are the same as the AST/HIR nesting.
641 /// However, from a name lookup point of view, the scopes look more like
642 /// as if the let-statements were `match` expressions:
645 /// fn foo(x: &str) {
647 /// match x.parse().unwrap() {
656 /// We care about the name-lookup scopes for debuginfo - if the
657 /// debuginfo instruction pointer is at the call to `x.parse()`, we
658 /// want `x` to refer to `x: &str`, but if it is at the call to
659 /// `drop(x)`, we want it to refer to `x: u32`.
661 /// To allow both uses to work, we need to have more than a single scope
662 /// for a local. We have the `source_info.scope` represent the
663 /// "syntactic" lint scope (with a variable being under its let
664 /// block) while the `visibility_scope` represents the "local variable"
665 /// scope (where the "rest" of a block is under all prior let-statements).
667 /// The end result looks like this:
671 /// │{ argument x: &str }
673 /// │ │{ #[allow(unused_mut] } // this is actually split into 2 scopes
674 /// │ │ // in practice because I'm lazy.
676 /// │ │← x.source_info.scope
677 /// │ │← `x.parse().unwrap()`
679 /// │ │ │← y.source_info.scope
681 /// │ │ │{ let y: u32 }
683 /// │ │ │← y.visibility_scope
686 /// │ │{ let x: u32 }
687 /// │ │← x.visibility_scope
688 /// │ │← `drop(x)` // this accesses `x: u32`
690 pub source_info: SourceInfo,
692 /// Source scope within which the local is visible (for debuginfo)
693 /// (see `source_info` for more details).
694 pub visibility_scope: SourceScope,
697 impl<'tcx> LocalDecl<'tcx> {
698 /// Returns true only if local is a binding that can itself be
699 /// made mutable via the addition of the `mut` keyword, namely
700 /// something like the occurrences of `x` in:
701 /// - `fn foo(x: Type) { ... }`,
703 /// - or `match ... { C(x) => ... }`
704 pub fn can_be_made_mutable(&self) -> bool {
705 match self.is_user_variable {
706 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
707 binding_mode: ty::BindingMode::BindByValue(_),
712 // FIXME: might be able to thread the distinction between
713 // `self`/`mut self`/`&self`/`&mut self` into the
714 // `BindingForm::ImplicitSelf` variant, (and then return
715 // true here for solely the first case).
720 /// Returns true if local is definitely not a `ref ident` or
721 /// `ref mut ident` binding. (Such bindings cannot be made into
722 /// mutable bindings, but the inverse does not necessarily hold).
723 pub fn is_nonref_binding(&self) -> bool {
724 match self.is_user_variable {
725 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
726 binding_mode: ty::BindingMode::BindByValue(_),
731 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf)) => true,
737 /// Create a new `LocalDecl` for a temporary.
739 pub fn new_temp(ty: Ty<'tcx>, span: Span) -> Self {
741 mutability: Mutability::Mut,
744 source_info: SourceInfo {
746 scope: OUTERMOST_SOURCE_SCOPE,
748 visibility_scope: OUTERMOST_SOURCE_SCOPE,
750 is_user_variable: None,
754 /// Create a new `LocalDecl` for a internal temporary.
756 pub fn new_internal(ty: Ty<'tcx>, span: Span) -> Self {
758 mutability: Mutability::Mut,
761 source_info: SourceInfo {
763 scope: OUTERMOST_SOURCE_SCOPE,
765 visibility_scope: OUTERMOST_SOURCE_SCOPE,
767 is_user_variable: None,
771 /// Builds a `LocalDecl` for the return place.
773 /// This must be inserted into the `local_decls` list as the first local.
775 pub fn new_return_place(return_ty: Ty, span: Span) -> LocalDecl {
777 mutability: Mutability::Mut,
779 source_info: SourceInfo {
781 scope: OUTERMOST_SOURCE_SCOPE,
783 visibility_scope: OUTERMOST_SOURCE_SCOPE,
785 name: None, // FIXME maybe we do want some name here?
786 is_user_variable: None,
791 /// A closure capture, with its name and mode.
792 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
793 pub struct UpvarDecl {
794 pub debug_name: Name,
796 /// `HirId` of the captured variable
797 pub var_hir_id: ClearCrossCrate<HirId>,
799 /// If true, the capture is behind a reference.
802 pub mutability: Mutability,
805 ///////////////////////////////////////////////////////////////////////////
808 newtype_index!(BasicBlock { DEBUG_FORMAT = "bb{}" });
811 pub fn start_location(self) -> Location {
819 ///////////////////////////////////////////////////////////////////////////
820 // BasicBlockData and Terminator
822 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
823 pub struct BasicBlockData<'tcx> {
824 /// List of statements in this block.
825 pub statements: Vec<Statement<'tcx>>,
827 /// Terminator for this block.
829 /// NB. This should generally ONLY be `None` during construction.
830 /// Therefore, you should generally access it via the
831 /// `terminator()` or `terminator_mut()` methods. The only
832 /// exception is that certain passes, such as `simplify_cfg`, swap
833 /// out the terminator temporarily with `None` while they continue
834 /// to recurse over the set of basic blocks.
835 pub terminator: Option<Terminator<'tcx>>,
837 /// If true, this block lies on an unwind path. This is used
838 /// during codegen where distinct kinds of basic blocks may be
839 /// generated (particularly for MSVC cleanup). Unwind blocks must
840 /// only branch to other unwind blocks.
841 pub is_cleanup: bool,
844 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
845 pub struct Terminator<'tcx> {
846 pub source_info: SourceInfo,
847 pub kind: TerminatorKind<'tcx>,
850 #[derive(Clone, RustcEncodable, RustcDecodable)]
851 pub enum TerminatorKind<'tcx> {
852 /// block should have one successor in the graph; we jump there
853 Goto { target: BasicBlock },
855 /// operand evaluates to an integer; jump depending on its value
856 /// to one of the targets, and otherwise fallback to `otherwise`
858 /// discriminant value being tested
859 discr: Operand<'tcx>,
861 /// type of value being tested
864 /// Possible values. The locations to branch to in each case
865 /// are found in the corresponding indices from the `targets` vector.
866 values: Cow<'tcx, [u128]>,
868 /// Possible branch sites. The last element of this vector is used
869 /// for the otherwise branch, so targets.len() == values.len() + 1
871 // This invariant is quite non-obvious and also could be improved.
872 // One way to make this invariant is to have something like this instead:
874 // branches: Vec<(ConstInt, BasicBlock)>,
875 // otherwise: Option<BasicBlock> // exhaustive if None
877 // However we’ve decided to keep this as-is until we figure a case
878 // where some other approach seems to be strictly better than other.
879 targets: Vec<BasicBlock>,
882 /// Indicates that the landing pad is finished and unwinding should
883 /// continue. Emitted by build::scope::diverge_cleanup.
886 /// Indicates that the landing pad is finished and that the process
887 /// should abort. Used to prevent unwinding for foreign items.
890 /// Indicates a normal return. The return place should have
891 /// been filled in by now. This should occur at most once.
894 /// Indicates a terminator that can never be reached.
899 location: Place<'tcx>,
901 unwind: Option<BasicBlock>,
904 /// Drop the Place and assign the new value over it. This ensures
905 /// that the assignment to `P` occurs *even if* the destructor for
906 /// place unwinds. Its semantics are best explained by by the
911 /// DropAndReplace(P <- V, goto BB1, unwind BB2)
919 /// Drop(P, goto BB1, unwind BB2)
922 /// // P is now unitialized
926 /// // P is now unitialized -- its dtor panicked
931 location: Place<'tcx>,
932 value: Operand<'tcx>,
934 unwind: Option<BasicBlock>,
937 /// Block ends with a call of a converging function
939 /// The function that’s being called
941 /// Arguments the function is called with.
942 /// These are owned by the callee, which is free to modify them.
943 /// This allows the memory occupied by "by-value" arguments to be
944 /// reused across function calls without duplicating the contents.
945 args: Vec<Operand<'tcx>>,
946 /// Destination for the return value. If some, the call is converging.
947 destination: Option<(Place<'tcx>, BasicBlock)>,
948 /// Cleanups to be done if the call unwinds.
949 cleanup: Option<BasicBlock>,
952 /// Jump to the target if the condition has the expected value,
953 /// otherwise panic with a message and a cleanup target.
957 msg: AssertMessage<'tcx>,
959 cleanup: Option<BasicBlock>,
964 /// The value to return
965 value: Operand<'tcx>,
966 /// Where to resume to
968 /// Cleanup to be done if the generator is dropped at this suspend point
969 drop: Option<BasicBlock>,
972 /// Indicates the end of the dropping of a generator
975 /// A block where control flow only ever takes one real path, but borrowck
976 /// needs to be more conservative.
978 /// The target normal control flow will take
979 real_target: BasicBlock,
980 /// The list of blocks control flow could conceptually take, but won't
982 imaginary_targets: Vec<BasicBlock>,
984 /// A terminator for blocks that only take one path in reality, but where we
985 /// reserve the right to unwind in borrowck, even if it won't happen in practice.
986 /// This can arise in infinite loops with no function calls for example.
988 /// The target normal control flow will take
989 real_target: BasicBlock,
990 /// The imaginary cleanup block link. This particular path will never be taken
991 /// in practice, but in order to avoid fragility we want to always
992 /// consider it in borrowck. We don't want to accept programs which
993 /// pass borrowck only when panic=abort or some assertions are disabled
994 /// due to release vs. debug mode builds. This needs to be an Option because
995 /// of the remove_noop_landing_pads and no_landing_pads passes
996 unwind: Option<BasicBlock>,
1000 pub type Successors<'a> =
1001 iter::Chain<option::IntoIter<&'a BasicBlock>, slice::Iter<'a, BasicBlock>>;
1002 pub type SuccessorsMut<'a> =
1003 iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>;
1005 impl<'tcx> Terminator<'tcx> {
1006 pub fn successors(&self) -> Successors {
1007 self.kind.successors()
1010 pub fn successors_mut(&mut self) -> SuccessorsMut {
1011 self.kind.successors_mut()
1014 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1018 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1019 self.kind.unwind_mut()
1023 impl<'tcx> TerminatorKind<'tcx> {
1024 pub fn if_<'a, 'gcx>(
1025 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1026 cond: Operand<'tcx>,
1029 ) -> TerminatorKind<'tcx> {
1030 static BOOL_SWITCH_FALSE: &'static [u128] = &[0];
1031 TerminatorKind::SwitchInt {
1033 switch_ty: tcx.types.bool,
1034 values: From::from(BOOL_SWITCH_FALSE),
1035 targets: vec![f, t],
1039 pub fn successors(&self) -> Successors {
1040 use self::TerminatorKind::*;
1051 } => None.into_iter().chain(&[]),
1052 Goto { target: ref t }
1055 cleanup: Some(ref t),
1059 destination: Some((_, ref t)),
1086 } => Some(t).into_iter().chain(&[]),
1088 destination: Some((_, ref t)),
1089 cleanup: Some(ref u),
1099 unwind: Some(ref u),
1104 unwind: Some(ref u),
1109 cleanup: Some(ref u),
1114 unwind: Some(ref u),
1115 } => Some(t).into_iter().chain(slice::from_ref(u)),
1116 SwitchInt { ref targets, .. } => None.into_iter().chain(&targets[..]),
1119 ref imaginary_targets,
1120 } => Some(real_target).into_iter().chain(&imaginary_targets[..]),
1124 pub fn successors_mut(&mut self) -> SuccessorsMut {
1125 use self::TerminatorKind::*;
1136 } => None.into_iter().chain(&mut []),
1137 Goto { target: ref mut t }
1140 cleanup: Some(ref mut t),
1144 destination: Some((_, ref mut t)),
1169 real_target: ref mut t,
1171 } => Some(t).into_iter().chain(&mut []),
1173 destination: Some((_, ref mut t)),
1174 cleanup: Some(ref mut u),
1179 drop: Some(ref mut u),
1184 unwind: Some(ref mut u),
1189 unwind: Some(ref mut u),
1194 cleanup: Some(ref mut u),
1198 real_target: ref mut t,
1199 unwind: Some(ref mut u),
1200 } => Some(t).into_iter().chain(slice::from_mut(u)),
1203 } => None.into_iter().chain(&mut targets[..]),
1205 ref mut real_target,
1206 ref mut imaginary_targets,
1207 } => Some(real_target)
1209 .chain(&mut imaginary_targets[..]),
1213 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1215 TerminatorKind::Goto { .. }
1216 | TerminatorKind::Resume
1217 | TerminatorKind::Abort
1218 | TerminatorKind::Return
1219 | TerminatorKind::Unreachable
1220 | TerminatorKind::GeneratorDrop
1221 | TerminatorKind::Yield { .. }
1222 | TerminatorKind::SwitchInt { .. }
1223 | TerminatorKind::FalseEdges { .. } => None,
1224 TerminatorKind::Call {
1225 cleanup: ref unwind,
1228 | TerminatorKind::Assert {
1229 cleanup: ref unwind,
1232 | TerminatorKind::DropAndReplace { ref unwind, .. }
1233 | TerminatorKind::Drop { ref unwind, .. }
1234 | TerminatorKind::FalseUnwind { ref unwind, .. } => Some(unwind),
1238 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1240 TerminatorKind::Goto { .. }
1241 | TerminatorKind::Resume
1242 | TerminatorKind::Abort
1243 | TerminatorKind::Return
1244 | TerminatorKind::Unreachable
1245 | TerminatorKind::GeneratorDrop
1246 | TerminatorKind::Yield { .. }
1247 | TerminatorKind::SwitchInt { .. }
1248 | TerminatorKind::FalseEdges { .. } => None,
1249 TerminatorKind::Call {
1250 cleanup: ref mut unwind,
1253 | TerminatorKind::Assert {
1254 cleanup: ref mut unwind,
1257 | TerminatorKind::DropAndReplace { ref mut unwind, .. }
1258 | TerminatorKind::Drop { ref mut unwind, .. }
1259 | TerminatorKind::FalseUnwind { ref mut unwind, .. } => Some(unwind),
1264 impl<'tcx> BasicBlockData<'tcx> {
1265 pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
1273 /// Accessor for terminator.
1275 /// Terminator may not be None after construction of the basic block is complete. This accessor
1276 /// provides a convenience way to reach the terminator.
1277 pub fn terminator(&self) -> &Terminator<'tcx> {
1278 self.terminator.as_ref().expect("invalid terminator state")
1281 pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
1282 self.terminator.as_mut().expect("invalid terminator state")
1285 pub fn retain_statements<F>(&mut self, mut f: F)
1287 F: FnMut(&mut Statement) -> bool,
1289 for s in &mut self.statements {
1296 pub fn expand_statements<F, I>(&mut self, mut f: F)
1298 F: FnMut(&mut Statement<'tcx>) -> Option<I>,
1299 I: iter::TrustedLen<Item = Statement<'tcx>>,
1301 // Gather all the iterators we'll need to splice in, and their positions.
1302 let mut splices: Vec<(usize, I)> = vec![];
1303 let mut extra_stmts = 0;
1304 for (i, s) in self.statements.iter_mut().enumerate() {
1305 if let Some(mut new_stmts) = f(s) {
1306 if let Some(first) = new_stmts.next() {
1307 // We can already store the first new statement.
1310 // Save the other statements for optimized splicing.
1311 let remaining = new_stmts.size_hint().0;
1313 splices.push((i + 1 + extra_stmts, new_stmts));
1314 extra_stmts += remaining;
1322 // Splice in the new statements, from the end of the block.
1323 // FIXME(eddyb) This could be more efficient with a "gap buffer"
1324 // where a range of elements ("gap") is left uninitialized, with
1325 // splicing adding new elements to the end of that gap and moving
1326 // existing elements from before the gap to the end of the gap.
1327 // For now, this is safe code, emulating a gap but initializing it.
1328 let mut gap = self.statements.len()..self.statements.len() + extra_stmts;
1329 self.statements.resize(
1332 source_info: SourceInfo {
1334 scope: OUTERMOST_SOURCE_SCOPE,
1336 kind: StatementKind::Nop,
1339 for (splice_start, new_stmts) in splices.into_iter().rev() {
1340 let splice_end = splice_start + new_stmts.size_hint().0;
1341 while gap.end > splice_end {
1344 self.statements.swap(gap.start, gap.end);
1346 self.statements.splice(splice_start..splice_end, new_stmts);
1347 gap.end = splice_start;
1351 pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
1352 if index < self.statements.len() {
1353 &self.statements[index]
1360 impl<'tcx> Debug for TerminatorKind<'tcx> {
1361 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1362 self.fmt_head(fmt)?;
1363 let successor_count = self.successors().count();
1364 let labels = self.fmt_successor_labels();
1365 assert_eq!(successor_count, labels.len());
1367 match successor_count {
1370 1 => write!(fmt, " -> {:?}", self.successors().nth(0).unwrap()),
1373 write!(fmt, " -> [")?;
1374 for (i, target) in self.successors().enumerate() {
1378 write!(fmt, "{}: {:?}", labels[i], target)?;
1386 impl<'tcx> TerminatorKind<'tcx> {
1387 /// Write the "head" part of the terminator; that is, its name and the data it uses to pick the
1388 /// successor basic block, if any. The only information not included is the list of possible
1389 /// successors, which may be rendered differently between the text and the graphviz format.
1390 pub fn fmt_head<W: Write>(&self, fmt: &mut W) -> fmt::Result {
1391 use self::TerminatorKind::*;
1393 Goto { .. } => write!(fmt, "goto"),
1395 discr: ref place, ..
1396 } => write!(fmt, "switchInt({:?})", place),
1397 Return => write!(fmt, "return"),
1398 GeneratorDrop => write!(fmt, "generator_drop"),
1399 Resume => write!(fmt, "resume"),
1400 Abort => write!(fmt, "abort"),
1401 Yield { ref value, .. } => write!(fmt, "_1 = suspend({:?})", value),
1402 Unreachable => write!(fmt, "unreachable"),
1403 Drop { ref location, .. } => write!(fmt, "drop({:?})", location),
1408 } => write!(fmt, "replace({:?} <- {:?})", location, value),
1415 if let Some((ref destination, _)) = *destination {
1416 write!(fmt, "{:?} = ", destination)?;
1418 write!(fmt, "{:?}(", func)?;
1419 for (index, arg) in args.iter().enumerate() {
1423 write!(fmt, "{:?}", arg)?;
1433 write!(fmt, "assert(")?;
1437 write!(fmt, "{:?}, \"{:?}\")", cond, msg)
1439 FalseEdges { .. } => write!(fmt, "falseEdges"),
1440 FalseUnwind { .. } => write!(fmt, "falseUnwind"),
1444 /// Return the list of labels for the edges to the successor basic blocks.
1445 pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> {
1446 use self::TerminatorKind::*;
1448 Return | Resume | Abort | Unreachable | GeneratorDrop => vec![],
1449 Goto { .. } => vec!["".into()],
1455 let size = ty::tls::with(|tcx| {
1456 let param_env = ty::ParamEnv::empty();
1457 let switch_ty = tcx.lift_to_global(&switch_ty).unwrap();
1458 tcx.layout_of(param_env.and(switch_ty)).unwrap().size
1463 let mut s = String::new();
1465 Value::Scalar(Scalar::Bits {
1467 defined: size.bits() as u8,
1474 .chain(iter::once(String::from("otherwise").into()))
1478 destination: Some(_),
1481 } => vec!["return".into_cow(), "unwind".into_cow()],
1483 destination: Some(_),
1486 } => vec!["return".into_cow()],
1491 } => vec!["unwind".into_cow()],
1497 Yield { drop: Some(_), .. } => vec!["resume".into_cow(), "drop".into_cow()],
1498 Yield { drop: None, .. } => vec!["resume".into_cow()],
1499 DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => {
1500 vec!["return".into_cow()]
1507 } => vec!["return".into_cow(), "unwind".into_cow()],
1508 Assert { cleanup: None, .. } => vec!["".into()],
1509 Assert { .. } => vec!["success".into_cow(), "unwind".into_cow()],
1511 ref imaginary_targets,
1514 let mut l = vec!["real".into()];
1515 l.resize(imaginary_targets.len() + 1, "imaginary".into());
1520 } => vec!["real".into(), "cleanup".into()],
1521 FalseUnwind { unwind: None, .. } => vec!["real".into()],
1526 ///////////////////////////////////////////////////////////////////////////
1529 #[derive(Clone, RustcEncodable, RustcDecodable)]
1530 pub struct Statement<'tcx> {
1531 pub source_info: SourceInfo,
1532 pub kind: StatementKind<'tcx>,
1535 impl<'tcx> Statement<'tcx> {
1536 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
1537 /// invalidating statement indices in `Location`s.
1538 pub fn make_nop(&mut self) {
1539 self.kind = StatementKind::Nop
1542 /// Changes a statement to a nop and returns the original statement.
1543 pub fn replace_nop(&mut self) -> Self {
1545 source_info: self.source_info,
1546 kind: mem::replace(&mut self.kind, StatementKind::Nop),
1551 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1552 pub enum StatementKind<'tcx> {
1553 /// Write the RHS Rvalue to the LHS Place.
1554 Assign(Place<'tcx>, Rvalue<'tcx>),
1556 /// This represents all the reading that a pattern match may do
1557 /// (e.g. inspecting constants and discriminant values).
1558 ReadForMatch(Place<'tcx>),
1560 /// Write the discriminant for a variant to the enum Place.
1563 variant_index: usize,
1566 /// Start a live range for the storage of the local.
1569 /// End the current live range for the storage of the local.
1572 /// Execute a piece of inline Assembly.
1574 asm: Box<InlineAsm>,
1575 outputs: Vec<Place<'tcx>>,
1576 inputs: Vec<Operand<'tcx>>,
1579 /// Assert the given places to be valid inhabitants of their type. These statements are
1580 /// currently only interpreted by miri and only generated when "-Z mir-emit-validate" is passed.
1581 /// See <https://internals.rust-lang.org/t/types-as-contracts/5562/73> for more details.
1582 Validate(ValidationOp, Vec<ValidationOperand<'tcx, Place<'tcx>>>),
1584 /// Mark one terminating point of a region scope (i.e. static region).
1585 /// (The starting point(s) arise implicitly from borrows.)
1586 EndRegion(region::Scope),
1588 /// Encodes a user's type assertion. These need to be preserved intact so that NLL can respect
1589 /// them. For example:
1591 /// let (a, b): (T, U) = y;
1593 /// Here we would insert a `UserAssertTy<(T, U)>(y)` instruction to check that the type of `y`
1594 /// is the right thing.
1596 /// `CanonicalTy` is used to capture "inference variables" from the user's types. For example:
1598 /// let x: Vec<_> = ...;
1599 /// let y: &u32 = ...;
1601 /// would result in `Vec<?0>` and `&'?0 u32` respectively (where `?0` is a canonicalized
1603 UserAssertTy(CanonicalTy<'tcx>, Local),
1605 /// No-op. Useful for deleting instructions without affecting statement indices.
1609 /// The `ValidationOp` describes what happens with each of the operands of a
1610 /// `Validate` statement.
1611 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, PartialEq, Eq)]
1612 pub enum ValidationOp {
1613 /// Recursively traverse the place following the type and validate that all type
1614 /// invariants are maintained. Furthermore, acquire exclusive/read-only access to the
1615 /// memory reachable from the place.
1617 /// Recursive traverse the *mutable* part of the type and relinquish all exclusive
1620 /// Recursive traverse the *mutable* part of the type and relinquish all exclusive
1621 /// access *until* the given region ends. Then, access will be recovered.
1622 Suspend(region::Scope),
1625 impl Debug for ValidationOp {
1626 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1627 use self::ValidationOp::*;
1629 Acquire => write!(fmt, "Acquire"),
1630 Release => write!(fmt, "Release"),
1631 // (reuse lifetime rendering policy from ppaux.)
1632 Suspend(ref ce) => write!(fmt, "Suspend({})", ty::ReScope(*ce)),
1637 // This is generic so that it can be reused by miri
1638 #[derive(Clone, RustcEncodable, RustcDecodable)]
1639 pub struct ValidationOperand<'tcx, T> {
1642 pub re: Option<region::Scope>,
1643 pub mutbl: hir::Mutability,
1646 impl<'tcx, T: Debug> Debug for ValidationOperand<'tcx, T> {
1647 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1648 write!(fmt, "{:?}: {:?}", self.place, self.ty)?;
1649 if let Some(ce) = self.re {
1650 // (reuse lifetime rendering policy from ppaux.)
1651 write!(fmt, "/{}", ty::ReScope(ce))?;
1653 if let hir::MutImmutable = self.mutbl {
1654 write!(fmt, " (imm)")?;
1660 impl<'tcx> Debug for Statement<'tcx> {
1661 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1662 use self::StatementKind::*;
1664 Assign(ref place, ref rv) => write!(fmt, "{:?} = {:?}", place, rv),
1665 ReadForMatch(ref place) => write!(fmt, "ReadForMatch({:?})", place),
1666 // (reuse lifetime rendering policy from ppaux.)
1667 EndRegion(ref ce) => write!(fmt, "EndRegion({})", ty::ReScope(*ce)),
1668 Validate(ref op, ref places) => write!(fmt, "Validate({:?}, {:?})", op, places),
1669 StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place),
1670 StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place),
1674 } => write!(fmt, "discriminant({:?}) = {:?}", place, variant_index),
1679 } => write!(fmt, "asm!({:?} : {:?} : {:?})", asm, outputs, inputs),
1680 UserAssertTy(ref c_ty, ref local) => {
1681 write!(fmt, "UserAssertTy({:?}, {:?})", c_ty, local)
1683 Nop => write!(fmt, "nop"),
1688 ///////////////////////////////////////////////////////////////////////////
1691 /// A path to a value; something that can be evaluated without
1692 /// changing or disturbing program state.
1693 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1694 pub enum Place<'tcx> {
1698 /// static or static mut variable
1699 Static(Box<Static<'tcx>>),
1701 /// projection out of a place (access a field, deref a pointer, etc)
1702 Projection(Box<PlaceProjection<'tcx>>),
1705 /// The def-id of a static, along with its normalized type (which is
1706 /// stored to avoid requiring normalization when reading MIR).
1707 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1708 pub struct Static<'tcx> {
1713 impl_stable_hash_for!(struct Static<'tcx> {
1718 /// The `Projection` data structure defines things of the form `B.x`
1719 /// or `*B` or `B[index]`. Note that it is parameterized because it is
1720 /// shared between `Constant` and `Place`. See the aliases
1721 /// `PlaceProjection` etc below.
1722 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1723 pub struct Projection<'tcx, B, V, T> {
1725 pub elem: ProjectionElem<'tcx, V, T>,
1728 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1729 pub enum ProjectionElem<'tcx, V, T> {
1734 /// These indices are generated by slice patterns. Easiest to explain
1738 /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
1739 /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
1740 /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
1741 /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
1744 /// index or -index (in Python terms), depending on from_end
1746 /// thing being indexed must be at least this long
1748 /// counting backwards from end?
1752 /// These indices are generated by slice patterns.
1754 /// slice[from:-to] in Python terms.
1760 /// "Downcast" to a variant of an ADT. Currently, we only introduce
1761 /// this for ADTs with more than one variant. It may be better to
1762 /// just introduce it always, or always for enums.
1763 Downcast(&'tcx AdtDef, usize),
1766 /// Alias for projections as they appear in places, where the base is a place
1767 /// and the index is a local.
1768 pub type PlaceProjection<'tcx> = Projection<'tcx, Place<'tcx>, Local, Ty<'tcx>>;
1770 /// Alias for projections as they appear in places, where the base is a place
1771 /// and the index is a local.
1772 pub type PlaceElem<'tcx> = ProjectionElem<'tcx, Local, Ty<'tcx>>;
1774 newtype_index!(Field { DEBUG_FORMAT = "field[{}]" });
1776 impl<'tcx> Place<'tcx> {
1777 pub fn field(self, f: Field, ty: Ty<'tcx>) -> Place<'tcx> {
1778 self.elem(ProjectionElem::Field(f, ty))
1781 pub fn deref(self) -> Place<'tcx> {
1782 self.elem(ProjectionElem::Deref)
1785 pub fn downcast(self, adt_def: &'tcx AdtDef, variant_index: usize) -> Place<'tcx> {
1786 self.elem(ProjectionElem::Downcast(adt_def, variant_index))
1789 pub fn index(self, index: Local) -> Place<'tcx> {
1790 self.elem(ProjectionElem::Index(index))
1793 pub fn elem(self, elem: PlaceElem<'tcx>) -> Place<'tcx> {
1794 Place::Projection(Box::new(PlaceProjection { base: self, elem }))
1798 impl<'tcx> Debug for Place<'tcx> {
1799 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1803 Local(id) => write!(fmt, "{:?}", id),
1804 Static(box self::Static { def_id, ty }) => write!(
1807 ty::tls::with(|tcx| tcx.item_path_str(def_id)),
1810 Projection(ref data) => match data.elem {
1811 ProjectionElem::Downcast(ref adt_def, index) => {
1812 write!(fmt, "({:?} as {})", data.base, adt_def.variants[index].name)
1814 ProjectionElem::Deref => write!(fmt, "(*{:?})", data.base),
1815 ProjectionElem::Field(field, ty) => {
1816 write!(fmt, "({:?}.{:?}: {:?})", data.base, field.index(), ty)
1818 ProjectionElem::Index(ref index) => write!(fmt, "{:?}[{:?}]", data.base, index),
1819 ProjectionElem::ConstantIndex {
1823 } => write!(fmt, "{:?}[{:?} of {:?}]", data.base, offset, min_length),
1824 ProjectionElem::ConstantIndex {
1828 } => write!(fmt, "{:?}[-{:?} of {:?}]", data.base, offset, min_length),
1829 ProjectionElem::Subslice { from, to } if to == 0 => {
1830 write!(fmt, "{:?}[{:?}:]", data.base, from)
1832 ProjectionElem::Subslice { from, to } if from == 0 => {
1833 write!(fmt, "{:?}[:-{:?}]", data.base, to)
1835 ProjectionElem::Subslice { from, to } => {
1836 write!(fmt, "{:?}[{:?}:-{:?}]", data.base, from, to)
1843 ///////////////////////////////////////////////////////////////////////////
1846 newtype_index!(SourceScope
1848 DEBUG_FORMAT = "scope[{}]",
1849 const OUTERMOST_SOURCE_SCOPE = 0,
1852 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1853 pub struct SourceScopeData {
1855 pub parent_scope: Option<SourceScope>,
1858 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1859 pub struct SourceScopeLocalData {
1860 /// A NodeId with lint levels equivalent to this scope's lint levels.
1861 pub lint_root: ast::NodeId,
1862 /// The unsafe block that contains this node.
1866 ///////////////////////////////////////////////////////////////////////////
1869 /// These are values that can appear inside an rvalue (or an index
1870 /// place). They are intentionally limited to prevent rvalues from
1871 /// being nested in one another.
1872 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
1873 pub enum Operand<'tcx> {
1874 /// Copy: The value must be available for use afterwards.
1876 /// This implies that the type of the place must be `Copy`; this is true
1877 /// by construction during build, but also checked by the MIR type checker.
1879 /// Move: The value (including old borrows of it) will not be used again.
1881 /// Safe for values of all types (modulo future developments towards `?Move`).
1882 /// Correct usage patterns are enforced by the borrow checker for safe code.
1883 /// `Copy` may be converted to `Move` to enable "last-use" optimizations.
1885 Constant(Box<Constant<'tcx>>),
1888 impl<'tcx> Debug for Operand<'tcx> {
1889 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1890 use self::Operand::*;
1892 Constant(ref a) => write!(fmt, "{:?}", a),
1893 Copy(ref place) => write!(fmt, "{:?}", place),
1894 Move(ref place) => write!(fmt, "move {:?}", place),
1899 impl<'tcx> Operand<'tcx> {
1900 pub fn function_handle<'a>(
1901 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1903 substs: &'tcx Substs<'tcx>,
1906 let ty = tcx.type_of(def_id).subst(tcx, substs);
1907 Operand::Constant(box Constant {
1910 literal: Literal::Value {
1911 value: ty::Const::zero_sized(tcx, ty),
1916 pub fn to_copy(&self) -> Self {
1918 Operand::Copy(_) | Operand::Constant(_) => self.clone(),
1919 Operand::Move(ref place) => Operand::Copy(place.clone()),
1924 ///////////////////////////////////////////////////////////////////////////
1927 #[derive(Clone, RustcEncodable, RustcDecodable)]
1928 pub enum Rvalue<'tcx> {
1929 /// x (either a move or copy, depending on type of x)
1933 Repeat(Operand<'tcx>, u64),
1936 Ref(Region<'tcx>, BorrowKind, Place<'tcx>),
1938 /// length of a [X] or [X;n] value
1941 Cast(CastKind, Operand<'tcx>, Ty<'tcx>),
1943 BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
1944 CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
1946 NullaryOp(NullOp, Ty<'tcx>),
1947 UnaryOp(UnOp, Operand<'tcx>),
1949 /// Read the discriminant of an ADT.
1951 /// Undefined (i.e. no effort is made to make it defined, but there’s no reason why it cannot
1952 /// be defined to return, say, a 0) if ADT is not an enum.
1953 Discriminant(Place<'tcx>),
1955 /// Create an aggregate value, like a tuple or struct. This is
1956 /// only needed because we want to distinguish `dest = Foo { x:
1957 /// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case
1958 /// that `Foo` has a destructor. These rvalues can be optimized
1959 /// away after type-checking and before lowering.
1960 Aggregate(Box<AggregateKind<'tcx>>, Vec<Operand<'tcx>>),
1963 #[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1967 /// Convert unique, zero-sized type for a fn to fn()
1970 /// Convert non capturing closure to fn()
1973 /// Convert safe fn() to unsafe fn()
1976 /// "Unsize" -- convert a thin-or-fat pointer to a fat pointer.
1977 /// codegen must figure out the details once full monomorphization
1978 /// is known. For example, this could be used to cast from a
1979 /// `&[i32;N]` to a `&[i32]`, or a `Box<T>` to a `Box<Trait>`
1980 /// (presuming `T: Trait`).
1984 #[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1985 pub enum AggregateKind<'tcx> {
1986 /// The type is of the element
1990 /// The second field is the variant index. It's equal to 0 for struct
1991 /// and union expressions. The fourth field is
1992 /// active field number and is present only for union expressions
1993 /// -- e.g. for a union expression `SomeUnion { c: .. }`, the
1994 /// active field index would identity the field `c`
1995 Adt(&'tcx AdtDef, usize, &'tcx Substs<'tcx>, Option<usize>),
1997 Closure(DefId, ClosureSubsts<'tcx>),
1998 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
2001 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2003 /// The `+` operator (addition)
2005 /// The `-` operator (subtraction)
2007 /// The `*` operator (multiplication)
2009 /// The `/` operator (division)
2011 /// The `%` operator (modulus)
2013 /// The `^` operator (bitwise xor)
2015 /// The `&` operator (bitwise and)
2017 /// The `|` operator (bitwise or)
2019 /// The `<<` operator (shift left)
2021 /// The `>>` operator (shift right)
2023 /// The `==` operator (equality)
2025 /// The `<` operator (less than)
2027 /// The `<=` operator (less than or equal to)
2029 /// The `!=` operator (not equal to)
2031 /// The `>=` operator (greater than or equal to)
2033 /// The `>` operator (greater than)
2035 /// The `ptr.offset` operator
2040 pub fn is_checkable(self) -> bool {
2043 Add | Sub | Mul | Shl | Shr => true,
2049 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2051 /// Return the size of a value of that type
2053 /// Create a new uninitialized box for a value of that type
2057 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2059 /// The `!` operator for logical inversion
2061 /// The `-` operator for negation
2065 impl<'tcx> Debug for Rvalue<'tcx> {
2066 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2067 use self::Rvalue::*;
2070 Use(ref place) => write!(fmt, "{:?}", place),
2071 Repeat(ref a, ref b) => write!(fmt, "[{:?}; {:?}]", a, b),
2072 Len(ref a) => write!(fmt, "Len({:?})", a),
2073 Cast(ref kind, ref place, ref ty) => {
2074 write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind)
2076 BinaryOp(ref op, ref a, ref b) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
2077 CheckedBinaryOp(ref op, ref a, ref b) => {
2078 write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b)
2080 UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
2081 Discriminant(ref place) => write!(fmt, "discriminant({:?})", place),
2082 NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
2083 Ref(region, borrow_kind, ref place) => {
2084 let kind_str = match borrow_kind {
2085 BorrowKind::Shared => "",
2086 BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ",
2089 // When printing regions, add trailing space if necessary.
2090 let region = if ppaux::verbose() || ppaux::identify_regions() {
2091 let mut region = format!("{}", region);
2092 if region.len() > 0 {
2097 // Do not even print 'static
2100 write!(fmt, "&{}{}{:?}", region, kind_str, place)
2103 Aggregate(ref kind, ref places) => {
2104 fn fmt_tuple(fmt: &mut Formatter, places: &[Operand]) -> fmt::Result {
2105 let mut tuple_fmt = fmt.debug_tuple("");
2106 for place in places {
2107 tuple_fmt.field(place);
2113 AggregateKind::Array(_) => write!(fmt, "{:?}", places),
2115 AggregateKind::Tuple => match places.len() {
2116 0 => write!(fmt, "()"),
2117 1 => write!(fmt, "({:?},)", places[0]),
2118 _ => fmt_tuple(fmt, places),
2121 AggregateKind::Adt(adt_def, variant, substs, _) => {
2122 let variant_def = &adt_def.variants[variant];
2124 ppaux::parameterized(fmt, substs, variant_def.did, &[])?;
2126 match variant_def.ctor_kind {
2127 CtorKind::Const => Ok(()),
2128 CtorKind::Fn => fmt_tuple(fmt, places),
2129 CtorKind::Fictive => {
2130 let mut struct_fmt = fmt.debug_struct("");
2131 for (field, place) in variant_def.fields.iter().zip(places) {
2132 struct_fmt.field(&field.ident.as_str(), place);
2139 AggregateKind::Closure(def_id, _) => ty::tls::with(|tcx| {
2140 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2141 let name = if tcx.sess.opts.debugging_opts.span_free_formats {
2142 format!("[closure@{:?}]", node_id)
2144 format!("[closure@{:?}]", tcx.hir.span(node_id))
2146 let mut struct_fmt = fmt.debug_struct(&name);
2148 tcx.with_freevars(node_id, |freevars| {
2149 for (freevar, place) in freevars.iter().zip(places) {
2150 let var_name = tcx.hir.name(freevar.var_id());
2151 struct_fmt.field(&var_name.as_str(), place);
2157 write!(fmt, "[closure]")
2161 AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
2162 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2163 let name = format!("[generator@{:?}]", tcx.hir.span(node_id));
2164 let mut struct_fmt = fmt.debug_struct(&name);
2166 tcx.with_freevars(node_id, |freevars| {
2167 for (freevar, place) in freevars.iter().zip(places) {
2168 let var_name = tcx.hir.name(freevar.var_id());
2169 struct_fmt.field(&var_name.as_str(), place);
2171 struct_fmt.field("$state", &places[freevars.len()]);
2172 for i in (freevars.len() + 1)..places.len() {
2174 .field(&format!("${}", i - freevars.len() - 1), &places[i]);
2180 write!(fmt, "[generator]")
2189 ///////////////////////////////////////////////////////////////////////////
2192 /// Two constants are equal if they are the same constant. Note that
2193 /// this does not necessarily mean that they are "==" in Rust -- in
2194 /// particular one must be wary of `NaN`!
2196 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2197 pub struct Constant<'tcx> {
2200 pub literal: Literal<'tcx>,
2203 newtype_index!(Promoted { DEBUG_FORMAT = "promoted[{}]" });
2205 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2206 pub enum Literal<'tcx> {
2208 value: &'tcx ty::Const<'tcx>,
2211 // Index into the `promoted` vector of `Mir`.
2216 impl<'tcx> Debug for Constant<'tcx> {
2217 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2218 write!(fmt, "{:?}", self.literal)
2222 impl<'tcx> Debug for Literal<'tcx> {
2223 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2224 use self::Literal::*;
2226 Value { value } => {
2227 write!(fmt, "const ")?;
2228 fmt_const_val(fmt, value)
2230 Promoted { index } => write!(fmt, "{:?}", index),
2235 /// Write a `ConstValue` in a way closer to the original source code than the `Debug` output.
2236 pub fn fmt_const_val<W: Write>(fmt: &mut W, const_val: &ty::Const) -> fmt::Result {
2237 if let Some(value) = const_val.to_byval_value() {
2238 print_miri_value(value, const_val.ty, fmt)
2240 write!(fmt, "{:?}:{}", const_val.val, const_val.ty)
2244 pub fn print_miri_value<W: Write>(value: Value, ty: Ty, f: &mut W) -> fmt::Result {
2245 use ty::TypeVariants::*;
2246 match (value, &ty.sty) {
2247 (Value::Scalar(Scalar::Bits { bits: 0, .. }), &TyBool) => write!(f, "false"),
2248 (Value::Scalar(Scalar::Bits { bits: 1, .. }), &TyBool) => write!(f, "true"),
2249 (Value::Scalar(Scalar::Bits { bits, .. }), &TyFloat(ast::FloatTy::F32)) => {
2250 write!(f, "{}f32", Single::from_bits(bits))
2252 (Value::Scalar(Scalar::Bits { bits, .. }), &TyFloat(ast::FloatTy::F64)) => {
2253 write!(f, "{}f64", Double::from_bits(bits))
2255 (Value::Scalar(Scalar::Bits { bits, .. }), &TyUint(ui)) => write!(f, "{:?}{}", bits, ui),
2256 (Value::Scalar(Scalar::Bits { bits, .. }), &TyInt(i)) => {
2257 let bit_width = ty::tls::with(|tcx| {
2258 let ty = tcx.lift_to_global(&ty).unwrap();
2259 tcx.layout_of(ty::ParamEnv::empty().and(ty))
2264 let shift = 128 - bit_width;
2265 write!(f, "{:?}{}", ((bits as i128) << shift) >> shift, i)
2267 (Value::Scalar(Scalar::Bits { bits, .. }), &TyChar) => {
2268 write!(f, "{:?}", ::std::char::from_u32(bits as u32).unwrap())
2270 (_, &TyFnDef(did, _)) => write!(f, "{}", item_path_str(did)),
2272 Value::ScalarPair(Scalar::Ptr(ptr), Scalar::Bits { bits: len, .. }),
2273 &TyRef(_, &ty::TyS { sty: TyStr, .. }, _),
2274 ) => ty::tls::with(|tcx| match tcx.alloc_map.lock().get(ptr.alloc_id) {
2275 Some(interpret::AllocType::Memory(alloc)) => {
2276 assert_eq!(len as usize as u128, len);
2277 let slice = &alloc.bytes[(ptr.offset.bytes() as usize)..][..(len as usize)];
2278 let s = ::std::str::from_utf8(slice).expect("non utf8 str from miri");
2279 write!(f, "{:?}", s)
2281 _ => write!(f, "pointer to erroneous constant {:?}, {:?}", ptr, len),
2283 _ => write!(f, "{:?}:{}", value, ty),
2287 fn item_path_str(def_id: DefId) -> String {
2288 ty::tls::with(|tcx| tcx.item_path_str(def_id))
2291 impl<'tcx> graph::DirectedGraph for Mir<'tcx> {
2292 type Node = BasicBlock;
2295 impl<'tcx> graph::WithNumNodes for Mir<'tcx> {
2296 fn num_nodes(&self) -> usize {
2297 self.basic_blocks.len()
2301 impl<'tcx> graph::WithStartNode for Mir<'tcx> {
2302 fn start_node(&self) -> Self::Node {
2307 impl<'tcx> graph::WithPredecessors for Mir<'tcx> {
2308 fn predecessors<'graph>(
2311 ) -> <Self as GraphPredecessors<'graph>>::Iter {
2312 self.predecessors_for(node).clone().into_iter()
2316 impl<'tcx> graph::WithSuccessors for Mir<'tcx> {
2317 fn successors<'graph>(
2320 ) -> <Self as GraphSuccessors<'graph>>::Iter {
2321 self.basic_blocks[node].terminator().successors().cloned()
2325 impl<'a, 'b> graph::GraphPredecessors<'b> for Mir<'a> {
2326 type Item = BasicBlock;
2327 type Iter = IntoIter<BasicBlock>;
2330 impl<'a, 'b> graph::GraphSuccessors<'b> for Mir<'a> {
2331 type Item = BasicBlock;
2332 type Iter = iter::Cloned<Successors<'b>>;
2335 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
2336 pub struct Location {
2337 /// the location is within this block
2338 pub block: BasicBlock,
2340 /// the location is the start of the statement; or, if `statement_index`
2341 /// == num-statements, then the start of the terminator.
2342 pub statement_index: usize,
2345 impl fmt::Debug for Location {
2346 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
2347 write!(fmt, "{:?}[{}]", self.block, self.statement_index)
2352 pub const START: Location = Location {
2357 /// Returns the location immediately after this one within the enclosing block.
2359 /// Note that if this location represents a terminator, then the
2360 /// resulting location would be out of bounds and invalid.
2361 pub fn successor_within_block(&self) -> Location {
2364 statement_index: self.statement_index + 1,
2368 pub fn dominates(&self, other: Location, dominators: &Dominators<BasicBlock>) -> bool {
2369 if self.block == other.block {
2370 self.statement_index <= other.statement_index
2372 dominators.is_dominated_by(other.block, self.block)
2377 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2378 pub enum UnsafetyViolationKind {
2380 ExternStatic(ast::NodeId),
2381 BorrowPacked(ast::NodeId),
2384 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2385 pub struct UnsafetyViolation {
2386 pub source_info: SourceInfo,
2387 pub description: InternedString,
2388 pub kind: UnsafetyViolationKind,
2391 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2392 pub struct UnsafetyCheckResult {
2393 /// Violations that are propagated *upwards* from this function
2394 pub violations: Lrc<[UnsafetyViolation]>,
2395 /// unsafe blocks in this function, along with whether they are used. This is
2396 /// used for the "unused_unsafe" lint.
2397 pub unsafe_blocks: Lrc<[(ast::NodeId, bool)]>,
2400 /// The layout of generator state
2401 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2402 pub struct GeneratorLayout<'tcx> {
2403 pub fields: Vec<LocalDecl<'tcx>>,
2406 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2407 pub struct BorrowCheckResult<'gcx> {
2408 pub closure_requirements: Option<ClosureRegionRequirements<'gcx>>,
2409 pub used_mut_upvars: SmallVec<[Field; 8]>,
2412 /// After we borrow check a closure, we are left with various
2413 /// requirements that we have inferred between the free regions that
2414 /// appear in the closure's signature or on its field types. These
2415 /// requirements are then verified and proved by the closure's
2416 /// creating function. This struct encodes those requirements.
2418 /// The requirements are listed as being between various
2419 /// `RegionVid`. The 0th region refers to `'static`; subsequent region
2420 /// vids refer to the free regions that appear in the closure (or
2421 /// generator's) type, in order of appearance. (This numbering is
2422 /// actually defined by the `UniversalRegions` struct in the NLL
2423 /// region checker. See for example
2424 /// `UniversalRegions::closure_mapping`.) Note that we treat the free
2425 /// regions in the closure's type "as if" they were erased, so their
2426 /// precise identity is not important, only their position.
2428 /// Example: If type check produces a closure with the closure substs:
2431 /// ClosureSubsts = [
2432 /// i8, // the "closure kind"
2433 /// for<'x> fn(&'a &'x u32) -> &'x u32, // the "closure signature"
2434 /// &'a String, // some upvar
2438 /// here, there is one unique free region (`'a`) but it appears
2439 /// twice. We would "renumber" each occurrence to a unique vid, as follows:
2442 /// ClosureSubsts = [
2443 /// i8, // the "closure kind"
2444 /// for<'x> fn(&'1 &'x u32) -> &'x u32, // the "closure signature"
2445 /// &'2 String, // some upvar
2449 /// Now the code might impose a requirement like `'1: '2`. When an
2450 /// instance of the closure is created, the corresponding free regions
2451 /// can be extracted from its type and constrained to have the given
2452 /// outlives relationship.
2454 /// In some cases, we have to record outlives requirements between
2455 /// types and regions as well. In that case, if those types include
2456 /// any regions, those regions are recorded as `ReClosureBound`
2457 /// instances assigned one of these same indices. Those regions will
2458 /// be substituted away by the creator. We use `ReClosureBound` in
2459 /// that case because the regions must be allocated in the global
2460 /// TyCtxt, and hence we cannot use `ReVar` (which is what we use
2461 /// internally within the rest of the NLL code).
2462 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2463 pub struct ClosureRegionRequirements<'gcx> {
2464 /// The number of external regions defined on the closure. In our
2465 /// example above, it would be 3 -- one for `'static`, then `'1`
2466 /// and `'2`. This is just used for a sanity check later on, to
2467 /// make sure that the number of regions we see at the callsite
2469 pub num_external_vids: usize,
2471 /// Requirements between the various free regions defined in
2473 pub outlives_requirements: Vec<ClosureOutlivesRequirement<'gcx>>,
2476 /// Indicates an outlives constraint between a type or between two
2477 /// free-regions declared on the closure.
2478 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2479 pub struct ClosureOutlivesRequirement<'tcx> {
2480 // This region or type ...
2481 pub subject: ClosureOutlivesSubject<'tcx>,
2483 // .. must outlive this one.
2484 pub outlived_free_region: ty::RegionVid,
2486 // If not, report an error here.
2487 pub blame_span: Span,
2490 /// The subject of a ClosureOutlivesRequirement -- that is, the thing
2491 /// that must outlive some region.
2492 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2493 pub enum ClosureOutlivesSubject<'tcx> {
2494 /// Subject is a type, typically a type parameter, but could also
2495 /// be a projection. Indicates a requirement like `T: 'a` being
2496 /// passed to the caller, where the type here is `T`.
2498 /// The type here is guaranteed not to contain any free regions at
2502 /// Subject is a free region from the closure. Indicates a requirement
2503 /// like `'a: 'b` being passed to the caller; the region here is `'a`.
2504 Region(ty::RegionVid),
2508 * TypeFoldable implementations for MIR types
2511 CloneTypeFoldableAndLiftImpls! {
2518 SourceScopeLocalData,
2521 BraceStructTypeFoldableImpl! {
2522 impl<'tcx> TypeFoldable<'tcx> for Mir<'tcx> {
2525 source_scope_local_data,
2539 BraceStructTypeFoldableImpl! {
2540 impl<'tcx> TypeFoldable<'tcx> for GeneratorLayout<'tcx> {
2545 BraceStructTypeFoldableImpl! {
2546 impl<'tcx> TypeFoldable<'tcx> for LocalDecl<'tcx> {
2557 BraceStructTypeFoldableImpl! {
2558 impl<'tcx> TypeFoldable<'tcx> for BasicBlockData<'tcx> {
2565 BraceStructTypeFoldableImpl! {
2566 impl<'tcx> TypeFoldable<'tcx> for ValidationOperand<'tcx, Place<'tcx>> {
2567 place, ty, re, mutbl
2571 BraceStructTypeFoldableImpl! {
2572 impl<'tcx> TypeFoldable<'tcx> for Statement<'tcx> {
2577 EnumTypeFoldableImpl! {
2578 impl<'tcx> TypeFoldable<'tcx> for StatementKind<'tcx> {
2579 (StatementKind::Assign)(a, b),
2580 (StatementKind::ReadForMatch)(place),
2581 (StatementKind::SetDiscriminant) { place, variant_index },
2582 (StatementKind::StorageLive)(a),
2583 (StatementKind::StorageDead)(a),
2584 (StatementKind::InlineAsm) { asm, outputs, inputs },
2585 (StatementKind::Validate)(a, b),
2586 (StatementKind::EndRegion)(a),
2587 (StatementKind::UserAssertTy)(a, b),
2588 (StatementKind::Nop),
2592 EnumTypeFoldableImpl! {
2593 impl<'tcx, T> TypeFoldable<'tcx> for ClearCrossCrate<T> {
2594 (ClearCrossCrate::Clear),
2595 (ClearCrossCrate::Set)(a),
2596 } where T: TypeFoldable<'tcx>
2599 impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
2600 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2601 use mir::TerminatorKind::*;
2603 let kind = match self.kind {
2604 Goto { target } => Goto { target: target },
2611 discr: discr.fold_with(folder),
2612 switch_ty: switch_ty.fold_with(folder),
2613 values: values.clone(),
2614 targets: targets.clone(),
2621 location: location.fold_with(folder),
2630 } => DropAndReplace {
2631 location: location.fold_with(folder),
2632 value: value.fold_with(folder),
2641 value: value.fold_with(folder),
2651 let dest = destination
2653 .map(|&(ref loc, dest)| (loc.fold_with(folder), dest));
2656 func: func.fold_with(folder),
2657 args: args.fold_with(folder),
2669 let msg = if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
2670 EvalErrorKind::BoundsCheck {
2671 len: len.fold_with(folder),
2672 index: index.fold_with(folder),
2678 cond: cond.fold_with(folder),
2685 GeneratorDrop => GeneratorDrop,
2689 Unreachable => Unreachable,
2692 ref imaginary_targets,
2695 imaginary_targets: imaginary_targets.clone(),
2706 source_info: self.source_info,
2711 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2712 use mir::TerminatorKind::*;
2719 } => discr.visit_with(visitor) || switch_ty.visit_with(visitor),
2720 Drop { ref location, .. } => location.visit_with(visitor),
2725 } => location.visit_with(visitor) || value.visit_with(visitor),
2726 Yield { ref value, .. } => value.visit_with(visitor),
2733 let dest = if let Some((ref loc, _)) = *destination {
2734 loc.visit_with(visitor)
2738 dest || func.visit_with(visitor) || args.visit_with(visitor)
2741 ref cond, ref msg, ..
2743 if cond.visit_with(visitor) {
2744 if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
2745 len.visit_with(visitor) || index.visit_with(visitor)
2760 | FalseUnwind { .. } => false,
2765 impl<'tcx> TypeFoldable<'tcx> for Place<'tcx> {
2766 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2768 &Place::Projection(ref p) => Place::Projection(p.fold_with(folder)),
2773 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2774 if let &Place::Projection(ref p) = self {
2775 p.visit_with(visitor)
2782 impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
2783 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2786 Use(ref op) => Use(op.fold_with(folder)),
2787 Repeat(ref op, len) => Repeat(op.fold_with(folder), len),
2788 Ref(region, bk, ref place) => {
2789 Ref(region.fold_with(folder), bk, place.fold_with(folder))
2791 Len(ref place) => Len(place.fold_with(folder)),
2792 Cast(kind, ref op, ty) => Cast(kind, op.fold_with(folder), ty.fold_with(folder)),
2793 BinaryOp(op, ref rhs, ref lhs) => {
2794 BinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
2796 CheckedBinaryOp(op, ref rhs, ref lhs) => {
2797 CheckedBinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
2799 UnaryOp(op, ref val) => UnaryOp(op, val.fold_with(folder)),
2800 Discriminant(ref place) => Discriminant(place.fold_with(folder)),
2801 NullaryOp(op, ty) => NullaryOp(op, ty.fold_with(folder)),
2802 Aggregate(ref kind, ref fields) => {
2803 let kind = box match **kind {
2804 AggregateKind::Array(ty) => AggregateKind::Array(ty.fold_with(folder)),
2805 AggregateKind::Tuple => AggregateKind::Tuple,
2806 AggregateKind::Adt(def, v, substs, n) => {
2807 AggregateKind::Adt(def, v, substs.fold_with(folder), n)
2809 AggregateKind::Closure(id, substs) => {
2810 AggregateKind::Closure(id, substs.fold_with(folder))
2812 AggregateKind::Generator(id, substs, movablity) => {
2813 AggregateKind::Generator(id, substs.fold_with(folder), movablity)
2816 Aggregate(kind, fields.fold_with(folder))
2821 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2824 Use(ref op) => op.visit_with(visitor),
2825 Repeat(ref op, _) => op.visit_with(visitor),
2826 Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor),
2827 Len(ref place) => place.visit_with(visitor),
2828 Cast(_, ref op, ty) => op.visit_with(visitor) || ty.visit_with(visitor),
2829 BinaryOp(_, ref rhs, ref lhs) | CheckedBinaryOp(_, ref rhs, ref lhs) => {
2830 rhs.visit_with(visitor) || lhs.visit_with(visitor)
2832 UnaryOp(_, ref val) => val.visit_with(visitor),
2833 Discriminant(ref place) => place.visit_with(visitor),
2834 NullaryOp(_, ty) => ty.visit_with(visitor),
2835 Aggregate(ref kind, ref fields) => {
2837 AggregateKind::Array(ty) => ty.visit_with(visitor),
2838 AggregateKind::Tuple => false,
2839 AggregateKind::Adt(_, _, substs, _) => substs.visit_with(visitor),
2840 AggregateKind::Closure(_, substs) => substs.visit_with(visitor),
2841 AggregateKind::Generator(_, substs, _) => substs.visit_with(visitor),
2842 }) || fields.visit_with(visitor)
2848 impl<'tcx> TypeFoldable<'tcx> for Operand<'tcx> {
2849 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2851 Operand::Copy(ref place) => Operand::Copy(place.fold_with(folder)),
2852 Operand::Move(ref place) => Operand::Move(place.fold_with(folder)),
2853 Operand::Constant(ref c) => Operand::Constant(c.fold_with(folder)),
2857 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2859 Operand::Copy(ref place) | Operand::Move(ref place) => place.visit_with(visitor),
2860 Operand::Constant(ref c) => c.visit_with(visitor),
2865 impl<'tcx, B, V, T> TypeFoldable<'tcx> for Projection<'tcx, B, V, T>
2867 B: TypeFoldable<'tcx>,
2868 V: TypeFoldable<'tcx>,
2869 T: TypeFoldable<'tcx>,
2871 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2872 use mir::ProjectionElem::*;
2874 let base = self.base.fold_with(folder);
2875 let elem = match self.elem {
2877 Field(f, ref ty) => Field(f, ty.fold_with(folder)),
2878 Index(ref v) => Index(v.fold_with(folder)),
2879 ref elem => elem.clone(),
2882 Projection { base, elem }
2885 fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool {
2886 use mir::ProjectionElem::*;
2888 self.base.visit_with(visitor) || match self.elem {
2889 Field(_, ref ty) => ty.visit_with(visitor),
2890 Index(ref v) => v.visit_with(visitor),
2896 impl<'tcx> TypeFoldable<'tcx> for Field {
2897 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _: &mut F) -> Self {
2900 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
2905 impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> {
2906 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2908 span: self.span.clone(),
2909 ty: self.ty.fold_with(folder),
2910 literal: self.literal.fold_with(folder),
2913 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2914 self.ty.visit_with(visitor) || self.literal.visit_with(visitor)
2918 impl<'tcx> TypeFoldable<'tcx> for Literal<'tcx> {
2919 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2921 Literal::Value { value } => Literal::Value {
2922 value: value.fold_with(folder),
2924 Literal::Promoted { index } => Literal::Promoted { index },
2927 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2929 Literal::Value { value } => value.visit_with(visitor),
2930 Literal::Promoted { .. } => false,