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, 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::control_flow_graph::dominators::{dominators, Dominators};
25 use rustc_data_structures::control_flow_graph::ControlFlowGraph;
26 use rustc_data_structures::control_flow_graph::{GraphPredecessors, GraphSuccessors};
27 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
28 use rustc_data_structures::small_vec::SmallVec;
29 use rustc_data_structures::sync::Lrc;
30 use rustc_data_structures::sync::ReadGuard;
31 use rustc_serialize as serialize;
33 use std::fmt::{self, Debug, Formatter, Write};
34 use std::ops::{Index, IndexMut};
36 use std::vec::IntoIter;
37 use std::{iter, mem, option, u32};
38 use syntax::ast::{self, Name};
39 use syntax::symbol::InternedString;
40 use syntax_pos::{Span, DUMMY_SP};
41 use ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
42 use ty::subst::{Subst, Substs};
43 use ty::{self, AdtDef, CanonicalTy, ClosureSubsts, GeneratorSubsts, Region, Ty, TyCtxt};
46 pub use mir::interpret::AssertMessage;
56 type LocalDecls<'tcx> = IndexVec<Local, LocalDecl<'tcx>>;
58 pub trait HasLocalDecls<'tcx> {
59 fn local_decls(&self) -> &LocalDecls<'tcx>;
62 impl<'tcx> HasLocalDecls<'tcx> for LocalDecls<'tcx> {
63 fn local_decls(&self) -> &LocalDecls<'tcx> {
68 impl<'tcx> HasLocalDecls<'tcx> for Mir<'tcx> {
69 fn local_decls(&self) -> &LocalDecls<'tcx> {
74 /// Lowered representation of a single function.
75 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
76 pub struct Mir<'tcx> {
77 /// List of basic blocks. References to basic block use a newtyped index type `BasicBlock`
78 /// that indexes into this vector.
79 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
81 /// List of source scopes; these are referenced by statements
82 /// and used for debuginfo. Indexed by a `SourceScope`.
83 pub source_scopes: IndexVec<SourceScope, SourceScopeData>,
85 /// Crate-local information for each source scope, that can't (and
86 /// needn't) be tracked across crates.
87 pub source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
89 /// Rvalues promoted from this function, such as borrows of constants.
90 /// Each of them is the Mir of a constant with the fn's type parameters
91 /// in scope, but a separate set of locals.
92 pub promoted: IndexVec<Promoted, Mir<'tcx>>,
94 /// Yield type of the function, if it is a generator.
95 pub yield_ty: Option<Ty<'tcx>>,
97 /// Generator drop glue
98 pub generator_drop: Option<Box<Mir<'tcx>>>,
100 /// The layout of a generator. Produced by the state transformation.
101 pub generator_layout: Option<GeneratorLayout<'tcx>>,
103 /// Declarations of locals.
105 /// The first local is the return value pointer, followed by `arg_count`
106 /// locals for the function arguments, followed by any user-declared
107 /// variables and temporaries.
108 pub local_decls: LocalDecls<'tcx>,
110 /// Number of arguments this function takes.
112 /// Starting at local 1, `arg_count` locals will be provided by the caller
113 /// and can be assumed to be initialized.
115 /// If this MIR was built for a constant, this will be 0.
116 pub arg_count: usize,
118 /// Names and capture modes of all the closure upvars, assuming
119 /// the first argument is either the closure or a reference to it.
120 pub upvar_decls: Vec<UpvarDecl>,
122 /// Mark an argument local (which must be a tuple) as getting passed as
123 /// its individual components at the LLVM level.
125 /// This is used for the "rust-call" ABI.
126 pub spread_arg: Option<Local>,
128 /// A span representing this MIR, for error reporting
131 /// A cache for various calculations
135 /// where execution begins
136 pub const START_BLOCK: BasicBlock = BasicBlock(0);
138 impl<'tcx> Mir<'tcx> {
140 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
141 source_scopes: IndexVec<SourceScope, SourceScopeData>,
142 source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
143 promoted: IndexVec<Promoted, Mir<'tcx>>,
144 yield_ty: Option<Ty<'tcx>>,
145 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
147 upvar_decls: Vec<UpvarDecl>,
150 // We need `arg_count` locals, and one for the return place
152 local_decls.len() >= arg_count + 1,
153 "expected at least {} locals, got {}",
161 source_scope_local_data,
164 generator_drop: None,
165 generator_layout: None,
171 cache: cache::Cache::new(),
176 pub fn basic_blocks(&self) -> &IndexVec<BasicBlock, BasicBlockData<'tcx>> {
181 pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
182 self.cache.invalidate();
183 &mut self.basic_blocks
187 pub fn basic_blocks_and_local_decls_mut(
190 &mut IndexVec<BasicBlock, BasicBlockData<'tcx>>,
191 &mut LocalDecls<'tcx>,
193 self.cache.invalidate();
194 (&mut self.basic_blocks, &mut self.local_decls)
198 pub fn predecessors(&self) -> ReadGuard<IndexVec<BasicBlock, Vec<BasicBlock>>> {
199 self.cache.predecessors(self)
203 pub fn predecessors_for(&self, bb: BasicBlock) -> ReadGuard<Vec<BasicBlock>> {
204 ReadGuard::map(self.predecessors(), |p| &p[bb])
208 pub fn dominators(&self) -> Dominators<BasicBlock> {
213 pub fn local_kind(&self, local: Local) -> LocalKind {
214 let index = local.0 as usize;
217 self.local_decls[local].mutability == Mutability::Mut,
218 "return place should be mutable"
221 LocalKind::ReturnPointer
222 } else if index < self.arg_count + 1 {
224 } else if self.local_decls[local].name.is_some() {
228 self.local_decls[local].mutability == Mutability::Mut,
229 "temp should be mutable"
236 /// Returns an iterator over all temporaries.
238 pub fn temps_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
239 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
240 let local = Local::new(index);
241 if self.local_decls[local].is_user_variable.is_some() {
249 /// Returns an iterator over all user-declared locals.
251 pub fn vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
252 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
253 let local = Local::new(index);
254 if self.local_decls[local].is_user_variable.is_some() {
262 /// Returns an iterator over all user-declared mutable arguments and locals.
264 pub fn mut_vars_and_args_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
265 (1..self.local_decls.len()).filter_map(move |index| {
266 let local = Local::new(index);
267 let decl = &self.local_decls[local];
268 if (decl.is_user_variable.is_some() || index < self.arg_count + 1)
269 && decl.mutability == Mutability::Mut
278 /// Returns an iterator over all function arguments.
280 pub fn args_iter(&self) -> impl Iterator<Item = Local> {
281 let arg_count = self.arg_count;
282 (1..arg_count + 1).map(Local::new)
285 /// Returns an iterator over all user-defined variables and compiler-generated temporaries (all
286 /// locals that are neither arguments nor the return place).
288 pub fn vars_and_temps_iter(&self) -> impl Iterator<Item = Local> {
289 let arg_count = self.arg_count;
290 let local_count = self.local_decls.len();
291 (arg_count + 1..local_count).map(Local::new)
294 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
295 /// invalidating statement indices in `Location`s.
296 pub fn make_statement_nop(&mut self, location: Location) {
297 let block = &mut self[location.block];
298 debug_assert!(location.statement_index < block.statements.len());
299 block.statements[location.statement_index].make_nop()
302 /// Returns the source info associated with `location`.
303 pub fn source_info(&self, location: Location) -> &SourceInfo {
304 let block = &self[location.block];
305 let stmts = &block.statements;
306 let idx = location.statement_index;
307 if idx < stmts.len() {
308 &stmts[idx].source_info
310 assert!(idx == stmts.len());
311 &block.terminator().source_info
315 /// Check if `sub` is a sub scope of `sup`
316 pub fn is_sub_scope(&self, mut sub: SourceScope, sup: SourceScope) -> bool {
321 match self.source_scopes[sub].parent_scope {
322 None => return false,
328 /// Return the return type, it always return first element from `local_decls` array
329 pub fn return_ty(&self) -> Ty<'tcx> {
330 self.local_decls[RETURN_PLACE].ty
334 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
337 /// Unsafe because of a PushUnsafeBlock
339 /// Unsafe because of an unsafe fn
341 /// Unsafe because of an `unsafe` block
342 ExplicitUnsafe(ast::NodeId),
345 impl_stable_hash_for!(struct Mir<'tcx> {
348 source_scope_local_data,
361 impl<'tcx> Index<BasicBlock> for Mir<'tcx> {
362 type Output = BasicBlockData<'tcx>;
365 fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
366 &self.basic_blocks()[index]
370 impl<'tcx> IndexMut<BasicBlock> for Mir<'tcx> {
372 fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> {
373 &mut self.basic_blocks_mut()[index]
377 #[derive(Copy, Clone, Debug)]
378 pub enum ClearCrossCrate<T> {
383 impl<T: serialize::Encodable> serialize::UseSpecializedEncodable for ClearCrossCrate<T> {}
384 impl<T: serialize::Decodable> serialize::UseSpecializedDecodable for ClearCrossCrate<T> {}
386 /// Grouped information about the source code origin of a MIR entity.
387 /// Intended to be inspected by diagnostics and debuginfo.
388 /// Most passes can work with it as a whole, within a single function.
389 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
390 pub struct SourceInfo {
391 /// Source span for the AST pertaining to this MIR entity.
394 /// The source scope, keeping track of which bindings can be
395 /// seen by debuginfo, active lint levels, `unsafe {...}`, etc.
396 pub scope: SourceScope,
399 ///////////////////////////////////////////////////////////////////////////
400 // Mutability and borrow kinds
402 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
403 pub enum Mutability {
408 impl From<Mutability> for hir::Mutability {
409 fn from(m: Mutability) -> Self {
411 Mutability::Mut => hir::MutMutable,
412 Mutability::Not => hir::MutImmutable,
417 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
418 pub enum BorrowKind {
419 /// Data must be immutable and is aliasable.
422 /// Data must be immutable but not aliasable. This kind of borrow
423 /// cannot currently be expressed by the user and is used only in
424 /// implicit closure bindings. It is needed when you the closure
425 /// is borrowing or mutating a mutable referent, e.g.:
427 /// let x: &mut isize = ...;
428 /// let y = || *x += 5;
430 /// If we were to try to translate this closure into a more explicit
431 /// form, we'd encounter an error with the code as written:
433 /// struct Env { x: & &mut isize }
434 /// let x: &mut isize = ...;
435 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
436 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
438 /// This is then illegal because you cannot mutate a `&mut` found
439 /// in an aliasable location. To solve, you'd have to translate with
440 /// an `&mut` borrow:
442 /// struct Env { x: & &mut isize }
443 /// let x: &mut isize = ...;
444 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
445 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
447 /// Now the assignment to `**env.x` is legal, but creating a
448 /// mutable pointer to `x` is not because `x` is not mutable. We
449 /// could fix this by declaring `x` as `let mut x`. This is ok in
450 /// user code, if awkward, but extra weird for closures, since the
451 /// borrow is hidden.
453 /// So we introduce a "unique imm" borrow -- the referent is
454 /// immutable, but not aliasable. This solves the problem. For
455 /// simplicity, we don't give users the way to express this
456 /// borrow, it's just used when translating closures.
459 /// Data is mutable and not aliasable.
461 /// True if this borrow arose from method-call auto-ref
462 /// (i.e. `adjustment::Adjust::Borrow`)
463 allow_two_phase_borrow: bool,
468 pub fn allows_two_phase_borrow(&self) -> bool {
470 BorrowKind::Shared | BorrowKind::Unique => false,
472 allow_two_phase_borrow,
473 } => allow_two_phase_borrow,
478 ///////////////////////////////////////////////////////////////////////////
479 // Variables and temps
483 DEBUG_FORMAT = "_{}",
484 const RETURN_PLACE = 0,
487 /// Classifies locals into categories. See `Mir::local_kind`.
488 #[derive(PartialEq, Eq, Debug)]
490 /// User-declared variable binding
492 /// Compiler-introduced temporary
494 /// Function argument
496 /// Location of function's return value
500 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
501 pub struct VarBindingForm<'tcx> {
502 /// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`?
503 pub binding_mode: ty::BindingMode,
504 /// If an explicit type was provided for this variable binding,
505 /// this holds the source Span of that type.
507 /// NOTE: If you want to change this to a `HirId`, be wary that
508 /// doing so breaks incremental compilation (as of this writing),
509 /// while a `Span` does not cause our tests to fail.
510 pub opt_ty_info: Option<Span>,
511 /// Place of the RHS of the =, or the subject of the `match` where this
512 /// variable is initialized. None in the case of `let PATTERN;`.
513 /// Some((None, ..)) in the case of and `let [mut] x = ...` because
514 /// (a) the right-hand side isn't evaluated as a place expression.
515 /// (b) it gives a way to separate this case from the remaining cases
517 pub opt_match_place: Option<(Option<Place<'tcx>>, Span)>,
520 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
521 pub enum BindingForm<'tcx> {
522 /// This is a binding for a non-`self` binding, or a `self` that has an explicit type.
523 Var(VarBindingForm<'tcx>),
524 /// Binding for a `self`/`&self`/`&mut self` binding where the type is implicit.
528 CloneTypeFoldableAndLiftImpls! { BindingForm<'tcx>, }
530 impl_stable_hash_for!(struct self::VarBindingForm<'tcx> {
536 mod binding_form_impl {
537 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableHasherResult};
538 use ich::StableHashingContext;
540 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
541 fn hash_stable<W: StableHasherResult>(&self,
542 hcx: &mut StableHashingContext<'a>,
543 hasher: &mut StableHasher<W>) {
544 use super::BindingForm::*;
545 ::std::mem::discriminant(self).hash_stable(hcx, hasher);
548 Var(binding) => binding.hash_stable(hcx, hasher),
557 /// This can be a binding declared by the user, a temporary inserted by the compiler, a function
558 /// argument, or the return place.
559 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
560 pub struct LocalDecl<'tcx> {
561 /// `let mut x` vs `let x`.
563 /// Temporaries and the return place are always mutable.
564 pub mutability: Mutability,
566 /// Some(binding_mode) if this corresponds to a user-declared local variable.
568 /// This is solely used for local diagnostics when generating
569 /// warnings/errors when compiling the current crate, and
570 /// therefore it need not be visible across crates. pnkfelix
571 /// currently hypothesized we *need* to wrap this in a
572 /// `ClearCrossCrate` as long as it carries as `HirId`.
573 pub is_user_variable: Option<ClearCrossCrate<BindingForm<'tcx>>>,
575 /// True if this is an internal local
577 /// These locals are not based on types in the source code and are only used
578 /// for a few desugarings at the moment.
580 /// The generator transformation will sanity check the locals which are live
581 /// across a suspension point against the type components of the generator
582 /// which type checking knows are live across a suspension point. We need to
583 /// flag drop flags to avoid triggering this check as they are introduced
586 /// Unsafety checking will also ignore dereferences of these locals,
587 /// so they can be used for raw pointers only used in a desugaring.
589 /// This should be sound because the drop flags are fully algebraic, and
590 /// therefore don't affect the OIBIT or outlives properties of the
594 /// Type of this local.
597 /// Name of the local, used in debuginfo and pretty-printing.
599 /// Note that function arguments can also have this set to `Some(_)`
600 /// to generate better debuginfo.
601 pub name: Option<Name>,
603 /// The *syntactic* (i.e. not visibility) source scope the local is defined
604 /// in. If the local was defined in a let-statement, this
605 /// is *within* the let-statement, rather than outside
608 /// This is needed because the visibility source scope of locals within
609 /// a let-statement is weird.
611 /// The reason is that we want the local to be *within* the let-statement
612 /// for lint purposes, but we want the local to be *after* the let-statement
613 /// for names-in-scope purposes.
615 /// That's it, if we have a let-statement like the one in this
619 /// fn foo(x: &str) {
620 /// #[allow(unused_mut)]
621 /// let mut x: u32 = { // <- one unused mut
622 /// let mut y: u32 = x.parse().unwrap();
629 /// Then, from a lint point of view, the declaration of `x: u32`
630 /// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the
631 /// lint scopes are the same as the AST/HIR nesting.
633 /// However, from a name lookup point of view, the scopes look more like
634 /// as if the let-statements were `match` expressions:
637 /// fn foo(x: &str) {
639 /// match x.parse().unwrap() {
648 /// We care about the name-lookup scopes for debuginfo - if the
649 /// debuginfo instruction pointer is at the call to `x.parse()`, we
650 /// want `x` to refer to `x: &str`, but if it is at the call to
651 /// `drop(x)`, we want it to refer to `x: u32`.
653 /// To allow both uses to work, we need to have more than a single scope
654 /// for a local. We have the `source_info.scope` represent the
655 /// "syntactic" lint scope (with a variable being under its let
656 /// block) while the `visibility_scope` represents the "local variable"
657 /// scope (where the "rest" of a block is under all prior let-statements).
659 /// The end result looks like this:
663 /// │{ argument x: &str }
665 /// │ │{ #[allow(unused_mut] } // this is actually split into 2 scopes
666 /// │ │ // in practice because I'm lazy.
668 /// │ │← x.source_info.scope
669 /// │ │← `x.parse().unwrap()`
671 /// │ │ │← y.source_info.scope
673 /// │ │ │{ let y: u32 }
675 /// │ │ │← y.visibility_scope
678 /// │ │{ let x: u32 }
679 /// │ │← x.visibility_scope
680 /// │ │← `drop(x)` // this accesses `x: u32`
682 pub source_info: SourceInfo,
684 /// Source scope within which the local is visible (for debuginfo)
685 /// (see `source_info` for more details).
686 pub visibility_scope: SourceScope,
689 impl<'tcx> LocalDecl<'tcx> {
690 /// Returns true only if local is a binding that can itself be
691 /// made mutable via the addition of the `mut` keyword, namely
692 /// something like the occurrences of `x` in:
693 /// - `fn foo(x: Type) { ... }`,
695 /// - or `match ... { C(x) => ... }`
696 pub fn can_be_made_mutable(&self) -> bool {
697 match self.is_user_variable {
698 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
699 binding_mode: ty::BindingMode::BindByValue(_),
704 // FIXME: might be able to thread the distinction between
705 // `self`/`mut self`/`&self`/`&mut self` into the
706 // `BindingForm::ImplicitSelf` variant, (and then return
707 // true here for solely the first case).
712 /// Returns true if local is definitely not a `ref ident` or
713 /// `ref mut ident` binding. (Such bindings cannot be made into
714 /// mutable bindings, but the inverse does not necessarily hold).
715 pub fn is_nonref_binding(&self) -> bool {
716 match self.is_user_variable {
717 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
718 binding_mode: ty::BindingMode::BindByValue(_),
723 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf)) => true,
729 /// Create a new `LocalDecl` for a temporary.
731 pub fn new_temp(ty: Ty<'tcx>, span: Span) -> Self {
733 mutability: Mutability::Mut,
736 source_info: SourceInfo {
738 scope: OUTERMOST_SOURCE_SCOPE,
740 visibility_scope: OUTERMOST_SOURCE_SCOPE,
742 is_user_variable: None,
746 /// Create a new `LocalDecl` for a internal temporary.
748 pub fn new_internal(ty: Ty<'tcx>, span: Span) -> Self {
750 mutability: Mutability::Mut,
753 source_info: SourceInfo {
755 scope: OUTERMOST_SOURCE_SCOPE,
757 visibility_scope: OUTERMOST_SOURCE_SCOPE,
759 is_user_variable: None,
763 /// Builds a `LocalDecl` for the return place.
765 /// This must be inserted into the `local_decls` list as the first local.
767 pub fn new_return_place(return_ty: Ty, span: Span) -> LocalDecl {
769 mutability: Mutability::Mut,
771 source_info: SourceInfo {
773 scope: OUTERMOST_SOURCE_SCOPE,
775 visibility_scope: OUTERMOST_SOURCE_SCOPE,
777 name: None, // FIXME maybe we do want some name here?
778 is_user_variable: None,
783 /// A closure capture, with its name and mode.
784 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
785 pub struct UpvarDecl {
786 pub debug_name: Name,
788 /// If true, the capture is behind a reference.
791 pub mutability: Mutability,
794 ///////////////////////////////////////////////////////////////////////////
797 newtype_index!(BasicBlock { DEBUG_FORMAT = "bb{}" });
800 pub fn start_location(self) -> Location {
808 ///////////////////////////////////////////////////////////////////////////
809 // BasicBlockData and Terminator
811 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
812 pub struct BasicBlockData<'tcx> {
813 /// List of statements in this block.
814 pub statements: Vec<Statement<'tcx>>,
816 /// Terminator for this block.
818 /// NB. This should generally ONLY be `None` during construction.
819 /// Therefore, you should generally access it via the
820 /// `terminator()` or `terminator_mut()` methods. The only
821 /// exception is that certain passes, such as `simplify_cfg`, swap
822 /// out the terminator temporarily with `None` while they continue
823 /// to recurse over the set of basic blocks.
824 pub terminator: Option<Terminator<'tcx>>,
826 /// If true, this block lies on an unwind path. This is used
827 /// during codegen where distinct kinds of basic blocks may be
828 /// generated (particularly for MSVC cleanup). Unwind blocks must
829 /// only branch to other unwind blocks.
830 pub is_cleanup: bool,
833 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
834 pub struct Terminator<'tcx> {
835 pub source_info: SourceInfo,
836 pub kind: TerminatorKind<'tcx>,
839 #[derive(Clone, RustcEncodable, RustcDecodable)]
840 pub enum TerminatorKind<'tcx> {
841 /// block should have one successor in the graph; we jump there
842 Goto { target: BasicBlock },
844 /// operand evaluates to an integer; jump depending on its value
845 /// to one of the targets, and otherwise fallback to `otherwise`
847 /// discriminant value being tested
848 discr: Operand<'tcx>,
850 /// type of value being tested
853 /// Possible values. The locations to branch to in each case
854 /// are found in the corresponding indices from the `targets` vector.
855 values: Cow<'tcx, [u128]>,
857 /// Possible branch sites. The last element of this vector is used
858 /// for the otherwise branch, so targets.len() == values.len() + 1
860 // This invariant is quite non-obvious and also could be improved.
861 // One way to make this invariant is to have something like this instead:
863 // branches: Vec<(ConstInt, BasicBlock)>,
864 // otherwise: Option<BasicBlock> // exhaustive if None
866 // However we’ve decided to keep this as-is until we figure a case
867 // where some other approach seems to be strictly better than other.
868 targets: Vec<BasicBlock>,
871 /// Indicates that the landing pad is finished and unwinding should
872 /// continue. Emitted by build::scope::diverge_cleanup.
875 /// Indicates that the landing pad is finished and that the process
876 /// should abort. Used to prevent unwinding for foreign items.
879 /// Indicates a normal return. The return place should have
880 /// been filled in by now. This should occur at most once.
883 /// Indicates a terminator that can never be reached.
888 location: Place<'tcx>,
890 unwind: Option<BasicBlock>,
893 /// Drop the Place and assign the new value over it. This ensures
894 /// that the assignment to `P` occurs *even if* the destructor for
895 /// place unwinds. Its semantics are best explained by by the
900 /// DropAndReplace(P <- V, goto BB1, unwind BB2)
908 /// Drop(P, goto BB1, unwind BB2)
911 /// // P is now unitialized
915 /// // P is now unitialized -- its dtor panicked
920 location: Place<'tcx>,
921 value: Operand<'tcx>,
923 unwind: Option<BasicBlock>,
926 /// Block ends with a call of a converging function
928 /// The function that’s being called
930 /// Arguments the function is called with.
931 /// These are owned by the callee, which is free to modify them.
932 /// This allows the memory occupied by "by-value" arguments to be
933 /// reused across function calls without duplicating the contents.
934 args: Vec<Operand<'tcx>>,
935 /// Destination for the return value. If some, the call is converging.
936 destination: Option<(Place<'tcx>, BasicBlock)>,
937 /// Cleanups to be done if the call unwinds.
938 cleanup: Option<BasicBlock>,
941 /// Jump to the target if the condition has the expected value,
942 /// otherwise panic with a message and a cleanup target.
946 msg: AssertMessage<'tcx>,
948 cleanup: Option<BasicBlock>,
953 /// The value to return
954 value: Operand<'tcx>,
955 /// Where to resume to
957 /// Cleanup to be done if the generator is dropped at this suspend point
958 drop: Option<BasicBlock>,
961 /// Indicates the end of the dropping of a generator
964 /// A block where control flow only ever takes one real path, but borrowck
965 /// needs to be more conservative.
967 /// The target normal control flow will take
968 real_target: BasicBlock,
969 /// The list of blocks control flow could conceptually take, but won't
971 imaginary_targets: Vec<BasicBlock>,
973 /// A terminator for blocks that only take one path in reality, but where we
974 /// reserve the right to unwind in borrowck, even if it won't happen in practice.
975 /// This can arise in infinite loops with no function calls for example.
977 /// The target normal control flow will take
978 real_target: BasicBlock,
979 /// The imaginary cleanup block link. This particular path will never be taken
980 /// in practice, but in order to avoid fragility we want to always
981 /// consider it in borrowck. We don't want to accept programs which
982 /// pass borrowck only when panic=abort or some assertions are disabled
983 /// due to release vs. debug mode builds. This needs to be an Option because
984 /// of the remove_noop_landing_pads and no_landing_pads passes
985 unwind: Option<BasicBlock>,
989 pub type Successors<'a> =
990 iter::Chain<option::IntoIter<&'a BasicBlock>, slice::Iter<'a, BasicBlock>>;
991 pub type SuccessorsMut<'a> =
992 iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>;
994 impl<'tcx> Terminator<'tcx> {
995 pub fn successors(&self) -> Successors {
996 self.kind.successors()
999 pub fn successors_mut(&mut self) -> SuccessorsMut {
1000 self.kind.successors_mut()
1003 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1007 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1008 self.kind.unwind_mut()
1012 impl<'tcx> TerminatorKind<'tcx> {
1013 pub fn if_<'a, 'gcx>(
1014 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1015 cond: Operand<'tcx>,
1018 ) -> TerminatorKind<'tcx> {
1019 static BOOL_SWITCH_FALSE: &'static [u128] = &[0];
1020 TerminatorKind::SwitchInt {
1022 switch_ty: tcx.types.bool,
1023 values: From::from(BOOL_SWITCH_FALSE),
1024 targets: vec![f, t],
1028 pub fn successors(&self) -> Successors {
1029 use self::TerminatorKind::*;
1040 } => None.into_iter().chain(&[]),
1041 Goto { target: ref t }
1044 cleanup: Some(ref t),
1048 destination: Some((_, ref t)),
1075 } => Some(t).into_iter().chain(&[]),
1077 destination: Some((_, ref t)),
1078 cleanup: Some(ref u),
1088 unwind: Some(ref u),
1093 unwind: Some(ref u),
1098 cleanup: Some(ref u),
1103 unwind: Some(ref u),
1104 } => Some(t).into_iter().chain(slice::from_ref(u)),
1105 SwitchInt { ref targets, .. } => None.into_iter().chain(&targets[..]),
1108 ref imaginary_targets,
1109 } => Some(real_target).into_iter().chain(&imaginary_targets[..]),
1113 pub fn successors_mut(&mut self) -> SuccessorsMut {
1114 use self::TerminatorKind::*;
1125 } => None.into_iter().chain(&mut []),
1126 Goto { target: ref mut t }
1129 cleanup: Some(ref mut t),
1133 destination: Some((_, ref mut t)),
1158 real_target: ref mut t,
1160 } => Some(t).into_iter().chain(&mut []),
1162 destination: Some((_, ref mut t)),
1163 cleanup: Some(ref mut u),
1168 drop: Some(ref mut u),
1173 unwind: Some(ref mut u),
1178 unwind: Some(ref mut u),
1183 cleanup: Some(ref mut u),
1187 real_target: ref mut t,
1188 unwind: Some(ref mut u),
1189 } => Some(t).into_iter().chain(slice::from_mut(u)),
1192 } => None.into_iter().chain(&mut targets[..]),
1194 ref mut real_target,
1195 ref mut imaginary_targets,
1196 } => Some(real_target)
1198 .chain(&mut imaginary_targets[..]),
1202 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1204 TerminatorKind::Goto { .. }
1205 | TerminatorKind::Resume
1206 | TerminatorKind::Abort
1207 | TerminatorKind::Return
1208 | TerminatorKind::Unreachable
1209 | TerminatorKind::GeneratorDrop
1210 | TerminatorKind::Yield { .. }
1211 | TerminatorKind::SwitchInt { .. }
1212 | TerminatorKind::FalseEdges { .. } => None,
1213 TerminatorKind::Call {
1214 cleanup: ref unwind,
1217 | TerminatorKind::Assert {
1218 cleanup: ref unwind,
1221 | TerminatorKind::DropAndReplace { ref unwind, .. }
1222 | TerminatorKind::Drop { ref unwind, .. }
1223 | TerminatorKind::FalseUnwind { ref unwind, .. } => Some(unwind),
1227 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1229 TerminatorKind::Goto { .. }
1230 | TerminatorKind::Resume
1231 | TerminatorKind::Abort
1232 | TerminatorKind::Return
1233 | TerminatorKind::Unreachable
1234 | TerminatorKind::GeneratorDrop
1235 | TerminatorKind::Yield { .. }
1236 | TerminatorKind::SwitchInt { .. }
1237 | TerminatorKind::FalseEdges { .. } => None,
1238 TerminatorKind::Call {
1239 cleanup: ref mut unwind,
1242 | TerminatorKind::Assert {
1243 cleanup: ref mut unwind,
1246 | TerminatorKind::DropAndReplace { ref mut unwind, .. }
1247 | TerminatorKind::Drop { ref mut unwind, .. }
1248 | TerminatorKind::FalseUnwind { ref mut unwind, .. } => Some(unwind),
1253 impl<'tcx> BasicBlockData<'tcx> {
1254 pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
1262 /// Accessor for terminator.
1264 /// Terminator may not be None after construction of the basic block is complete. This accessor
1265 /// provides a convenience way to reach the terminator.
1266 pub fn terminator(&self) -> &Terminator<'tcx> {
1267 self.terminator.as_ref().expect("invalid terminator state")
1270 pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
1271 self.terminator.as_mut().expect("invalid terminator state")
1274 pub fn retain_statements<F>(&mut self, mut f: F)
1276 F: FnMut(&mut Statement) -> bool,
1278 for s in &mut self.statements {
1285 pub fn expand_statements<F, I>(&mut self, mut f: F)
1287 F: FnMut(&mut Statement<'tcx>) -> Option<I>,
1288 I: iter::TrustedLen<Item = Statement<'tcx>>,
1290 // Gather all the iterators we'll need to splice in, and their positions.
1291 let mut splices: Vec<(usize, I)> = vec![];
1292 let mut extra_stmts = 0;
1293 for (i, s) in self.statements.iter_mut().enumerate() {
1294 if let Some(mut new_stmts) = f(s) {
1295 if let Some(first) = new_stmts.next() {
1296 // We can already store the first new statement.
1299 // Save the other statements for optimized splicing.
1300 let remaining = new_stmts.size_hint().0;
1302 splices.push((i + 1 + extra_stmts, new_stmts));
1303 extra_stmts += remaining;
1311 // Splice in the new statements, from the end of the block.
1312 // FIXME(eddyb) This could be more efficient with a "gap buffer"
1313 // where a range of elements ("gap") is left uninitialized, with
1314 // splicing adding new elements to the end of that gap and moving
1315 // existing elements from before the gap to the end of the gap.
1316 // For now, this is safe code, emulating a gap but initializing it.
1317 let mut gap = self.statements.len()..self.statements.len() + extra_stmts;
1318 self.statements.resize(
1321 source_info: SourceInfo {
1323 scope: OUTERMOST_SOURCE_SCOPE,
1325 kind: StatementKind::Nop,
1328 for (splice_start, new_stmts) in splices.into_iter().rev() {
1329 let splice_end = splice_start + new_stmts.size_hint().0;
1330 while gap.end > splice_end {
1333 self.statements.swap(gap.start, gap.end);
1335 self.statements.splice(splice_start..splice_end, new_stmts);
1336 gap.end = splice_start;
1340 pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
1341 if index < self.statements.len() {
1342 &self.statements[index]
1349 impl<'tcx> Debug for TerminatorKind<'tcx> {
1350 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1351 self.fmt_head(fmt)?;
1352 let successor_count = self.successors().count();
1353 let labels = self.fmt_successor_labels();
1354 assert_eq!(successor_count, labels.len());
1356 match successor_count {
1359 1 => write!(fmt, " -> {:?}", self.successors().nth(0).unwrap()),
1362 write!(fmt, " -> [")?;
1363 for (i, target) in self.successors().enumerate() {
1367 write!(fmt, "{}: {:?}", labels[i], target)?;
1375 impl<'tcx> TerminatorKind<'tcx> {
1376 /// Write the "head" part of the terminator; that is, its name and the data it uses to pick the
1377 /// successor basic block, if any. The only information not included is the list of possible
1378 /// successors, which may be rendered differently between the text and the graphviz format.
1379 pub fn fmt_head<W: Write>(&self, fmt: &mut W) -> fmt::Result {
1380 use self::TerminatorKind::*;
1382 Goto { .. } => write!(fmt, "goto"),
1384 discr: ref place, ..
1385 } => write!(fmt, "switchInt({:?})", place),
1386 Return => write!(fmt, "return"),
1387 GeneratorDrop => write!(fmt, "generator_drop"),
1388 Resume => write!(fmt, "resume"),
1389 Abort => write!(fmt, "abort"),
1390 Yield { ref value, .. } => write!(fmt, "_1 = suspend({:?})", value),
1391 Unreachable => write!(fmt, "unreachable"),
1392 Drop { ref location, .. } => write!(fmt, "drop({:?})", location),
1397 } => write!(fmt, "replace({:?} <- {:?})", location, value),
1404 if let Some((ref destination, _)) = *destination {
1405 write!(fmt, "{:?} = ", destination)?;
1407 write!(fmt, "{:?}(", func)?;
1408 for (index, arg) in args.iter().enumerate() {
1412 write!(fmt, "{:?}", arg)?;
1422 write!(fmt, "assert(")?;
1426 write!(fmt, "{:?}, \"{:?}\")", cond, msg)
1428 FalseEdges { .. } => write!(fmt, "falseEdges"),
1429 FalseUnwind { .. } => write!(fmt, "falseUnwind"),
1433 /// Return the list of labels for the edges to the successor basic blocks.
1434 pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> {
1435 use self::TerminatorKind::*;
1437 Return | Resume | Abort | Unreachable | GeneratorDrop => vec![],
1438 Goto { .. } => vec!["".into()],
1444 let size = ty::tls::with(|tcx| {
1445 let param_env = ty::ParamEnv::empty();
1446 let switch_ty = tcx.lift_to_global(&switch_ty).unwrap();
1447 tcx.layout_of(param_env.and(switch_ty)).unwrap().size
1452 let mut s = String::new();
1454 Value::Scalar(Scalar::Bits {
1456 defined: size.bits() as u8,
1463 .chain(iter::once(String::from("otherwise").into()))
1467 destination: Some(_),
1470 } => vec!["return".into_cow(), "unwind".into_cow()],
1472 destination: Some(_),
1475 } => vec!["return".into_cow()],
1480 } => vec!["unwind".into_cow()],
1486 Yield { drop: Some(_), .. } => vec!["resume".into_cow(), "drop".into_cow()],
1487 Yield { drop: None, .. } => vec!["resume".into_cow()],
1488 DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => {
1489 vec!["return".into_cow()]
1496 } => vec!["return".into_cow(), "unwind".into_cow()],
1497 Assert { cleanup: None, .. } => vec!["".into()],
1498 Assert { .. } => vec!["success".into_cow(), "unwind".into_cow()],
1500 ref imaginary_targets,
1503 let mut l = vec!["real".into()];
1504 l.resize(imaginary_targets.len() + 1, "imaginary".into());
1509 } => vec!["real".into(), "cleanup".into()],
1510 FalseUnwind { unwind: None, .. } => vec!["real".into()],
1515 ///////////////////////////////////////////////////////////////////////////
1518 #[derive(Clone, RustcEncodable, RustcDecodable)]
1519 pub struct Statement<'tcx> {
1520 pub source_info: SourceInfo,
1521 pub kind: StatementKind<'tcx>,
1524 impl<'tcx> Statement<'tcx> {
1525 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
1526 /// invalidating statement indices in `Location`s.
1527 pub fn make_nop(&mut self) {
1528 self.kind = StatementKind::Nop
1531 /// Changes a statement to a nop and returns the original statement.
1532 pub fn replace_nop(&mut self) -> Self {
1534 source_info: self.source_info,
1535 kind: mem::replace(&mut self.kind, StatementKind::Nop),
1540 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1541 pub enum StatementKind<'tcx> {
1542 /// Write the RHS Rvalue to the LHS Place.
1543 Assign(Place<'tcx>, Rvalue<'tcx>),
1545 /// This represents all the reading that a pattern match may do
1546 /// (e.g. inspecting constants and discriminant values).
1547 ReadForMatch(Place<'tcx>),
1549 /// Write the discriminant for a variant to the enum Place.
1552 variant_index: usize,
1555 /// Start a live range for the storage of the local.
1558 /// End the current live range for the storage of the local.
1561 /// Execute a piece of inline Assembly.
1563 asm: Box<InlineAsm>,
1564 outputs: Vec<Place<'tcx>>,
1565 inputs: Vec<Operand<'tcx>>,
1568 /// Assert the given places to be valid inhabitants of their type. These statements are
1569 /// currently only interpreted by miri and only generated when "-Z mir-emit-validate" is passed.
1570 /// See <https://internals.rust-lang.org/t/types-as-contracts/5562/73> for more details.
1571 Validate(ValidationOp, Vec<ValidationOperand<'tcx, Place<'tcx>>>),
1573 /// Mark one terminating point of a region scope (i.e. static region).
1574 /// (The starting point(s) arise implicitly from borrows.)
1575 EndRegion(region::Scope),
1577 /// Encodes a user's type assertion. These need to be preserved intact so that NLL can respect
1578 /// them. For example:
1580 /// let (a, b): (T, U) = y;
1582 /// Here we would insert a `UserAssertTy<(T, U)>(y)` instruction to check that the type of `y`
1583 /// is the right thing.
1585 /// `CanonicalTy` is used to capture "inference variables" from the user's types. For example:
1587 /// let x: Vec<_> = ...;
1588 /// let y: &u32 = ...;
1590 /// would result in `Vec<?0>` and `&'?0 u32` respectively (where `?0` is a canonicalized
1592 UserAssertTy(CanonicalTy<'tcx>, Local),
1594 /// No-op. Useful for deleting instructions without affecting statement indices.
1598 /// The `ValidationOp` describes what happens with each of the operands of a
1599 /// `Validate` statement.
1600 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, PartialEq, Eq)]
1601 pub enum ValidationOp {
1602 /// Recursively traverse the place following the type and validate that all type
1603 /// invariants are maintained. Furthermore, acquire exclusive/read-only access to the
1604 /// memory reachable from the place.
1606 /// Recursive traverse the *mutable* part of the type and relinquish all exclusive
1609 /// Recursive traverse the *mutable* part of the type and relinquish all exclusive
1610 /// access *until* the given region ends. Then, access will be recovered.
1611 Suspend(region::Scope),
1614 impl Debug for ValidationOp {
1615 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1616 use self::ValidationOp::*;
1618 Acquire => write!(fmt, "Acquire"),
1619 Release => write!(fmt, "Release"),
1620 // (reuse lifetime rendering policy from ppaux.)
1621 Suspend(ref ce) => write!(fmt, "Suspend({})", ty::ReScope(*ce)),
1626 // This is generic so that it can be reused by miri
1627 #[derive(Clone, RustcEncodable, RustcDecodable)]
1628 pub struct ValidationOperand<'tcx, T> {
1631 pub re: Option<region::Scope>,
1632 pub mutbl: hir::Mutability,
1635 impl<'tcx, T: Debug> Debug for ValidationOperand<'tcx, T> {
1636 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1637 write!(fmt, "{:?}: {:?}", self.place, self.ty)?;
1638 if let Some(ce) = self.re {
1639 // (reuse lifetime rendering policy from ppaux.)
1640 write!(fmt, "/{}", ty::ReScope(ce))?;
1642 if let hir::MutImmutable = self.mutbl {
1643 write!(fmt, " (imm)")?;
1649 impl<'tcx> Debug for Statement<'tcx> {
1650 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1651 use self::StatementKind::*;
1653 Assign(ref place, ref rv) => write!(fmt, "{:?} = {:?}", place, rv),
1654 ReadForMatch(ref place) => write!(fmt, "ReadForMatch({:?})", place),
1655 // (reuse lifetime rendering policy from ppaux.)
1656 EndRegion(ref ce) => write!(fmt, "EndRegion({})", ty::ReScope(*ce)),
1657 Validate(ref op, ref places) => write!(fmt, "Validate({:?}, {:?})", op, places),
1658 StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place),
1659 StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place),
1663 } => write!(fmt, "discriminant({:?}) = {:?}", place, variant_index),
1668 } => write!(fmt, "asm!({:?} : {:?} : {:?})", asm, outputs, inputs),
1669 UserAssertTy(ref c_ty, ref local) => {
1670 write!(fmt, "UserAssertTy({:?}, {:?})", c_ty, local)
1672 Nop => write!(fmt, "nop"),
1677 ///////////////////////////////////////////////////////////////////////////
1680 /// A path to a value; something that can be evaluated without
1681 /// changing or disturbing program state.
1682 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1683 pub enum Place<'tcx> {
1687 /// static or static mut variable
1688 Static(Box<Static<'tcx>>),
1690 /// projection out of a place (access a field, deref a pointer, etc)
1691 Projection(Box<PlaceProjection<'tcx>>),
1694 /// The def-id of a static, along with its normalized type (which is
1695 /// stored to avoid requiring normalization when reading MIR).
1696 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1697 pub struct Static<'tcx> {
1702 impl_stable_hash_for!(struct Static<'tcx> {
1707 /// The `Projection` data structure defines things of the form `B.x`
1708 /// or `*B` or `B[index]`. Note that it is parameterized because it is
1709 /// shared between `Constant` and `Place`. See the aliases
1710 /// `PlaceProjection` etc below.
1711 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1712 pub struct Projection<'tcx, B, V, T> {
1714 pub elem: ProjectionElem<'tcx, V, T>,
1717 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1718 pub enum ProjectionElem<'tcx, V, T> {
1723 /// These indices are generated by slice patterns. Easiest to explain
1727 /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
1728 /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
1729 /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
1730 /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
1733 /// index or -index (in Python terms), depending on from_end
1735 /// thing being indexed must be at least this long
1737 /// counting backwards from end?
1741 /// These indices are generated by slice patterns.
1743 /// slice[from:-to] in Python terms.
1749 /// "Downcast" to a variant of an ADT. Currently, we only introduce
1750 /// this for ADTs with more than one variant. It may be better to
1751 /// just introduce it always, or always for enums.
1752 Downcast(&'tcx AdtDef, usize),
1755 /// Alias for projections as they appear in places, where the base is a place
1756 /// and the index is a local.
1757 pub type PlaceProjection<'tcx> = Projection<'tcx, Place<'tcx>, Local, Ty<'tcx>>;
1759 /// Alias for projections as they appear in places, where the base is a place
1760 /// and the index is a local.
1761 pub type PlaceElem<'tcx> = ProjectionElem<'tcx, Local, Ty<'tcx>>;
1763 newtype_index!(Field { DEBUG_FORMAT = "field[{}]" });
1765 impl<'tcx> Place<'tcx> {
1766 pub fn field(self, f: Field, ty: Ty<'tcx>) -> Place<'tcx> {
1767 self.elem(ProjectionElem::Field(f, ty))
1770 pub fn deref(self) -> Place<'tcx> {
1771 self.elem(ProjectionElem::Deref)
1774 pub fn downcast(self, adt_def: &'tcx AdtDef, variant_index: usize) -> Place<'tcx> {
1775 self.elem(ProjectionElem::Downcast(adt_def, variant_index))
1778 pub fn index(self, index: Local) -> Place<'tcx> {
1779 self.elem(ProjectionElem::Index(index))
1782 pub fn elem(self, elem: PlaceElem<'tcx>) -> Place<'tcx> {
1783 Place::Projection(Box::new(PlaceProjection { base: self, elem }))
1787 impl<'tcx> Debug for Place<'tcx> {
1788 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1792 Local(id) => write!(fmt, "{:?}", id),
1793 Static(box self::Static { def_id, ty }) => write!(
1796 ty::tls::with(|tcx| tcx.item_path_str(def_id)),
1799 Projection(ref data) => match data.elem {
1800 ProjectionElem::Downcast(ref adt_def, index) => {
1801 write!(fmt, "({:?} as {})", data.base, adt_def.variants[index].name)
1803 ProjectionElem::Deref => write!(fmt, "(*{:?})", data.base),
1804 ProjectionElem::Field(field, ty) => {
1805 write!(fmt, "({:?}.{:?}: {:?})", data.base, field.index(), ty)
1807 ProjectionElem::Index(ref index) => write!(fmt, "{:?}[{:?}]", data.base, index),
1808 ProjectionElem::ConstantIndex {
1812 } => write!(fmt, "{:?}[{:?} of {:?}]", data.base, offset, min_length),
1813 ProjectionElem::ConstantIndex {
1817 } => write!(fmt, "{:?}[-{:?} of {:?}]", data.base, offset, min_length),
1818 ProjectionElem::Subslice { from, to } if to == 0 => {
1819 write!(fmt, "{:?}[{:?}:]", data.base, from)
1821 ProjectionElem::Subslice { from, to } if from == 0 => {
1822 write!(fmt, "{:?}[:-{:?}]", data.base, to)
1824 ProjectionElem::Subslice { from, to } => {
1825 write!(fmt, "{:?}[{:?}:-{:?}]", data.base, from, to)
1832 ///////////////////////////////////////////////////////////////////////////
1835 newtype_index!(SourceScope
1837 DEBUG_FORMAT = "scope[{}]",
1838 const OUTERMOST_SOURCE_SCOPE = 0,
1841 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1842 pub struct SourceScopeData {
1844 pub parent_scope: Option<SourceScope>,
1847 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1848 pub struct SourceScopeLocalData {
1849 /// A NodeId with lint levels equivalent to this scope's lint levels.
1850 pub lint_root: ast::NodeId,
1851 /// The unsafe block that contains this node.
1855 ///////////////////////////////////////////////////////////////////////////
1858 /// These are values that can appear inside an rvalue (or an index
1859 /// place). They are intentionally limited to prevent rvalues from
1860 /// being nested in one another.
1861 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
1862 pub enum Operand<'tcx> {
1863 /// Copy: The value must be available for use afterwards.
1865 /// This implies that the type of the place must be `Copy`; this is true
1866 /// by construction during build, but also checked by the MIR type checker.
1868 /// Move: The value (including old borrows of it) will not be used again.
1870 /// Safe for values of all types (modulo future developments towards `?Move`).
1871 /// Correct usage patterns are enforced by the borrow checker for safe code.
1872 /// `Copy` may be converted to `Move` to enable "last-use" optimizations.
1874 Constant(Box<Constant<'tcx>>),
1877 impl<'tcx> Debug for Operand<'tcx> {
1878 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1879 use self::Operand::*;
1881 Constant(ref a) => write!(fmt, "{:?}", a),
1882 Copy(ref place) => write!(fmt, "{:?}", place),
1883 Move(ref place) => write!(fmt, "move {:?}", place),
1888 impl<'tcx> Operand<'tcx> {
1889 pub fn function_handle<'a>(
1890 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1892 substs: &'tcx Substs<'tcx>,
1895 let ty = tcx.type_of(def_id).subst(tcx, substs);
1896 Operand::Constant(box Constant {
1899 literal: Literal::Value {
1900 value: ty::Const::zero_sized(tcx, ty),
1905 pub fn to_copy(&self) -> Self {
1907 Operand::Copy(_) | Operand::Constant(_) => self.clone(),
1908 Operand::Move(ref place) => Operand::Copy(place.clone()),
1913 ///////////////////////////////////////////////////////////////////////////
1916 #[derive(Clone, RustcEncodable, RustcDecodable)]
1917 pub enum Rvalue<'tcx> {
1918 /// x (either a move or copy, depending on type of x)
1922 Repeat(Operand<'tcx>, u64),
1925 Ref(Region<'tcx>, BorrowKind, Place<'tcx>),
1927 /// length of a [X] or [X;n] value
1930 Cast(CastKind, Operand<'tcx>, Ty<'tcx>),
1932 BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
1933 CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
1935 NullaryOp(NullOp, Ty<'tcx>),
1936 UnaryOp(UnOp, Operand<'tcx>),
1938 /// Read the discriminant of an ADT.
1940 /// Undefined (i.e. no effort is made to make it defined, but there’s no reason why it cannot
1941 /// be defined to return, say, a 0) if ADT is not an enum.
1942 Discriminant(Place<'tcx>),
1944 /// Create an aggregate value, like a tuple or struct. This is
1945 /// only needed because we want to distinguish `dest = Foo { x:
1946 /// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case
1947 /// that `Foo` has a destructor. These rvalues can be optimized
1948 /// away after type-checking and before lowering.
1949 Aggregate(Box<AggregateKind<'tcx>>, Vec<Operand<'tcx>>),
1952 #[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1956 /// Convert unique, zero-sized type for a fn to fn()
1959 /// Convert non capturing closure to fn()
1962 /// Convert safe fn() to unsafe fn()
1965 /// "Unsize" -- convert a thin-or-fat pointer to a fat pointer.
1966 /// codegen must figure out the details once full monomorphization
1967 /// is known. For example, this could be used to cast from a
1968 /// `&[i32;N]` to a `&[i32]`, or a `Box<T>` to a `Box<Trait>`
1969 /// (presuming `T: Trait`).
1973 #[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1974 pub enum AggregateKind<'tcx> {
1975 /// The type is of the element
1979 /// The second field is the variant index. It's equal to 0 for struct
1980 /// and union expressions. The fourth field is
1981 /// active field number and is present only for union expressions
1982 /// -- e.g. for a union expression `SomeUnion { c: .. }`, the
1983 /// active field index would identity the field `c`
1984 Adt(&'tcx AdtDef, usize, &'tcx Substs<'tcx>, Option<usize>),
1986 Closure(DefId, ClosureSubsts<'tcx>),
1987 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
1990 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1992 /// The `+` operator (addition)
1994 /// The `-` operator (subtraction)
1996 /// The `*` operator (multiplication)
1998 /// The `/` operator (division)
2000 /// The `%` operator (modulus)
2002 /// The `^` operator (bitwise xor)
2004 /// The `&` operator (bitwise and)
2006 /// The `|` operator (bitwise or)
2008 /// The `<<` operator (shift left)
2010 /// The `>>` operator (shift right)
2012 /// The `==` operator (equality)
2014 /// The `<` operator (less than)
2016 /// The `<=` operator (less than or equal to)
2018 /// The `!=` operator (not equal to)
2020 /// The `>=` operator (greater than or equal to)
2022 /// The `>` operator (greater than)
2024 /// The `ptr.offset` operator
2029 pub fn is_checkable(self) -> bool {
2032 Add | Sub | Mul | Shl | Shr => true,
2038 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2040 /// Return the size of a value of that type
2042 /// Create a new uninitialized box for a value of that type
2046 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2048 /// The `!` operator for logical inversion
2050 /// The `-` operator for negation
2054 impl<'tcx> Debug for Rvalue<'tcx> {
2055 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2056 use self::Rvalue::*;
2059 Use(ref place) => write!(fmt, "{:?}", place),
2060 Repeat(ref a, ref b) => write!(fmt, "[{:?}; {:?}]", a, b),
2061 Len(ref a) => write!(fmt, "Len({:?})", a),
2062 Cast(ref kind, ref place, ref ty) => {
2063 write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind)
2065 BinaryOp(ref op, ref a, ref b) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
2066 CheckedBinaryOp(ref op, ref a, ref b) => {
2067 write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b)
2069 UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
2070 Discriminant(ref place) => write!(fmt, "discriminant({:?})", place),
2071 NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
2072 Ref(region, borrow_kind, ref place) => {
2073 let kind_str = match borrow_kind {
2074 BorrowKind::Shared => "",
2075 BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ",
2078 // When printing regions, add trailing space if necessary.
2079 let region = if ppaux::verbose() || ppaux::identify_regions() {
2080 let mut region = format!("{}", region);
2081 if region.len() > 0 {
2086 // Do not even print 'static
2089 write!(fmt, "&{}{}{:?}", region, kind_str, place)
2092 Aggregate(ref kind, ref places) => {
2093 fn fmt_tuple(fmt: &mut Formatter, places: &[Operand]) -> fmt::Result {
2094 let mut tuple_fmt = fmt.debug_tuple("");
2095 for place in places {
2096 tuple_fmt.field(place);
2102 AggregateKind::Array(_) => write!(fmt, "{:?}", places),
2104 AggregateKind::Tuple => match places.len() {
2105 0 => write!(fmt, "()"),
2106 1 => write!(fmt, "({:?},)", places[0]),
2107 _ => fmt_tuple(fmt, places),
2110 AggregateKind::Adt(adt_def, variant, substs, _) => {
2111 let variant_def = &adt_def.variants[variant];
2113 ppaux::parameterized(fmt, substs, variant_def.did, &[])?;
2115 match variant_def.ctor_kind {
2116 CtorKind::Const => Ok(()),
2117 CtorKind::Fn => fmt_tuple(fmt, places),
2118 CtorKind::Fictive => {
2119 let mut struct_fmt = fmt.debug_struct("");
2120 for (field, place) in variant_def.fields.iter().zip(places) {
2121 struct_fmt.field(&field.ident.as_str(), place);
2128 AggregateKind::Closure(def_id, _) => ty::tls::with(|tcx| {
2129 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2130 let name = if tcx.sess.opts.debugging_opts.span_free_formats {
2131 format!("[closure@{:?}]", node_id)
2133 format!("[closure@{:?}]", tcx.hir.span(node_id))
2135 let mut struct_fmt = fmt.debug_struct(&name);
2137 tcx.with_freevars(node_id, |freevars| {
2138 for (freevar, place) in freevars.iter().zip(places) {
2139 let var_name = tcx.hir.name(freevar.var_id());
2140 struct_fmt.field(&var_name.as_str(), place);
2146 write!(fmt, "[closure]")
2150 AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
2151 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2152 let name = format!("[generator@{:?}]", tcx.hir.span(node_id));
2153 let mut struct_fmt = fmt.debug_struct(&name);
2155 tcx.with_freevars(node_id, |freevars| {
2156 for (freevar, place) in freevars.iter().zip(places) {
2157 let var_name = tcx.hir.name(freevar.var_id());
2158 struct_fmt.field(&var_name.as_str(), place);
2160 struct_fmt.field("$state", &places[freevars.len()]);
2161 for i in (freevars.len() + 1)..places.len() {
2163 .field(&format!("${}", i - freevars.len() - 1), &places[i]);
2169 write!(fmt, "[generator]")
2178 ///////////////////////////////////////////////////////////////////////////
2181 /// Two constants are equal if they are the same constant. Note that
2182 /// this does not necessarily mean that they are "==" in Rust -- in
2183 /// particular one must be wary of `NaN`!
2185 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2186 pub struct Constant<'tcx> {
2189 pub literal: Literal<'tcx>,
2192 newtype_index!(Promoted { DEBUG_FORMAT = "promoted[{}]" });
2194 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2195 pub enum Literal<'tcx> {
2197 value: &'tcx ty::Const<'tcx>,
2200 // Index into the `promoted` vector of `Mir`.
2205 impl<'tcx> Debug for Constant<'tcx> {
2206 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2207 write!(fmt, "{:?}", self.literal)
2211 impl<'tcx> Debug for Literal<'tcx> {
2212 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2213 use self::Literal::*;
2215 Value { value } => {
2216 write!(fmt, "const ")?;
2217 fmt_const_val(fmt, value)
2219 Promoted { index } => write!(fmt, "{:?}", index),
2224 /// Write a `ConstValue` in a way closer to the original source code than the `Debug` output.
2225 pub fn fmt_const_val<W: Write>(fmt: &mut W, const_val: &ty::Const) -> fmt::Result {
2226 if let Some(value) = const_val.to_byval_value() {
2227 print_miri_value(value, const_val.ty, fmt)
2229 write!(fmt, "{:?}:{}", const_val.val, const_val.ty)
2233 pub fn print_miri_value<W: Write>(value: Value, ty: Ty, f: &mut W) -> fmt::Result {
2234 use ty::TypeVariants::*;
2235 match (value, &ty.sty) {
2236 (Value::Scalar(Scalar::Bits { bits: 0, .. }), &TyBool) => write!(f, "false"),
2237 (Value::Scalar(Scalar::Bits { bits: 1, .. }), &TyBool) => write!(f, "true"),
2238 (Value::Scalar(Scalar::Bits { bits, .. }), &TyFloat(ast::FloatTy::F32)) => {
2239 write!(f, "{}f32", Single::from_bits(bits))
2241 (Value::Scalar(Scalar::Bits { bits, .. }), &TyFloat(ast::FloatTy::F64)) => {
2242 write!(f, "{}f64", Double::from_bits(bits))
2244 (Value::Scalar(Scalar::Bits { bits, .. }), &TyUint(ui)) => write!(f, "{:?}{}", bits, ui),
2245 (Value::Scalar(Scalar::Bits { bits, .. }), &TyInt(i)) => {
2246 let bit_width = ty::tls::with(|tcx| {
2247 let ty = tcx.lift_to_global(&ty).unwrap();
2248 tcx.layout_of(ty::ParamEnv::empty().and(ty))
2253 let shift = 128 - bit_width;
2254 write!(f, "{:?}{}", ((bits as i128) << shift) >> shift, i)
2256 (Value::Scalar(Scalar::Bits { bits, .. }), &TyChar) => {
2257 write!(f, "{:?}", ::std::char::from_u32(bits as u32).unwrap())
2259 (_, &TyFnDef(did, _)) => write!(f, "{}", item_path_str(did)),
2261 Value::ScalarPair(Scalar::Ptr(ptr), Scalar::Bits { bits: len, .. }),
2262 &TyRef(_, &ty::TyS { sty: TyStr, .. }, _),
2263 ) => ty::tls::with(|tcx| match tcx.alloc_map.lock().get(ptr.alloc_id) {
2264 Some(interpret::AllocType::Memory(alloc)) => {
2265 assert_eq!(len as usize as u128, len);
2266 let slice = &alloc.bytes[(ptr.offset.bytes() as usize)..][..(len as usize)];
2267 let s = ::std::str::from_utf8(slice).expect("non utf8 str from miri");
2268 write!(f, "{:?}", s)
2270 _ => write!(f, "pointer to erroneous constant {:?}, {:?}", ptr, len),
2272 _ => write!(f, "{:?}:{}", value, ty),
2276 fn item_path_str(def_id: DefId) -> String {
2277 ty::tls::with(|tcx| tcx.item_path_str(def_id))
2280 impl<'tcx> ControlFlowGraph for Mir<'tcx> {
2281 type Node = BasicBlock;
2283 fn num_nodes(&self) -> usize {
2284 self.basic_blocks.len()
2287 fn start_node(&self) -> Self::Node {
2291 fn predecessors<'graph>(
2294 ) -> <Self as GraphPredecessors<'graph>>::Iter {
2295 self.predecessors_for(node).clone().into_iter()
2297 fn successors<'graph>(
2300 ) -> <Self as GraphSuccessors<'graph>>::Iter {
2301 self.basic_blocks[node].terminator().successors().cloned()
2305 impl<'a, 'b> GraphPredecessors<'b> for Mir<'a> {
2306 type Item = BasicBlock;
2307 type Iter = IntoIter<BasicBlock>;
2310 impl<'a, 'b> GraphSuccessors<'b> for Mir<'a> {
2311 type Item = BasicBlock;
2312 type Iter = iter::Cloned<Successors<'b>>;
2315 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
2316 pub struct Location {
2317 /// the location is within this block
2318 pub block: BasicBlock,
2320 /// the location is the start of the statement; or, if `statement_index`
2321 /// == num-statements, then the start of the terminator.
2322 pub statement_index: usize,
2325 impl fmt::Debug for Location {
2326 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
2327 write!(fmt, "{:?}[{}]", self.block, self.statement_index)
2332 pub const START: Location = Location {
2337 /// Returns the location immediately after this one within the enclosing block.
2339 /// Note that if this location represents a terminator, then the
2340 /// resulting location would be out of bounds and invalid.
2341 pub fn successor_within_block(&self) -> Location {
2344 statement_index: self.statement_index + 1,
2348 pub fn dominates(&self, other: Location, dominators: &Dominators<BasicBlock>) -> bool {
2349 if self.block == other.block {
2350 self.statement_index <= other.statement_index
2352 dominators.is_dominated_by(other.block, self.block)
2357 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2358 pub enum UnsafetyViolationKind {
2360 ExternStatic(ast::NodeId),
2361 BorrowPacked(ast::NodeId),
2364 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2365 pub struct UnsafetyViolation {
2366 pub source_info: SourceInfo,
2367 pub description: InternedString,
2368 pub kind: UnsafetyViolationKind,
2371 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2372 pub struct UnsafetyCheckResult {
2373 /// Violations that are propagated *upwards* from this function
2374 pub violations: Lrc<[UnsafetyViolation]>,
2375 /// unsafe blocks in this function, along with whether they are used. This is
2376 /// used for the "unused_unsafe" lint.
2377 pub unsafe_blocks: Lrc<[(ast::NodeId, bool)]>,
2380 /// The layout of generator state
2381 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2382 pub struct GeneratorLayout<'tcx> {
2383 pub fields: Vec<LocalDecl<'tcx>>,
2386 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2387 pub struct BorrowCheckResult<'gcx> {
2388 pub closure_requirements: Option<ClosureRegionRequirements<'gcx>>,
2389 pub used_mut_upvars: SmallVec<[Field; 8]>,
2392 /// After we borrow check a closure, we are left with various
2393 /// requirements that we have inferred between the free regions that
2394 /// appear in the closure's signature or on its field types. These
2395 /// requirements are then verified and proved by the closure's
2396 /// creating function. This struct encodes those requirements.
2398 /// The requirements are listed as being between various
2399 /// `RegionVid`. The 0th region refers to `'static`; subsequent region
2400 /// vids refer to the free regions that appear in the closure (or
2401 /// generator's) type, in order of appearance. (This numbering is
2402 /// actually defined by the `UniversalRegions` struct in the NLL
2403 /// region checker. See for example
2404 /// `UniversalRegions::closure_mapping`.) Note that we treat the free
2405 /// regions in the closure's type "as if" they were erased, so their
2406 /// precise identity is not important, only their position.
2408 /// Example: If type check produces a closure with the closure substs:
2411 /// ClosureSubsts = [
2412 /// i8, // the "closure kind"
2413 /// for<'x> fn(&'a &'x u32) -> &'x u32, // the "closure signature"
2414 /// &'a String, // some upvar
2418 /// here, there is one unique free region (`'a`) but it appears
2419 /// twice. We would "renumber" each occurrence to a unique vid, as follows:
2422 /// ClosureSubsts = [
2423 /// i8, // the "closure kind"
2424 /// for<'x> fn(&'1 &'x u32) -> &'x u32, // the "closure signature"
2425 /// &'2 String, // some upvar
2429 /// Now the code might impose a requirement like `'1: '2`. When an
2430 /// instance of the closure is created, the corresponding free regions
2431 /// can be extracted from its type and constrained to have the given
2432 /// outlives relationship.
2434 /// In some cases, we have to record outlives requirements between
2435 /// types and regions as well. In that case, if those types include
2436 /// any regions, those regions are recorded as `ReClosureBound`
2437 /// instances assigned one of these same indices. Those regions will
2438 /// be substituted away by the creator. We use `ReClosureBound` in
2439 /// that case because the regions must be allocated in the global
2440 /// TyCtxt, and hence we cannot use `ReVar` (which is what we use
2441 /// internally within the rest of the NLL code).
2442 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2443 pub struct ClosureRegionRequirements<'gcx> {
2444 /// The number of external regions defined on the closure. In our
2445 /// example above, it would be 3 -- one for `'static`, then `'1`
2446 /// and `'2`. This is just used for a sanity check later on, to
2447 /// make sure that the number of regions we see at the callsite
2449 pub num_external_vids: usize,
2451 /// Requirements between the various free regions defined in
2453 pub outlives_requirements: Vec<ClosureOutlivesRequirement<'gcx>>,
2456 /// Indicates an outlives constraint between a type or between two
2457 /// free-regions declared on the closure.
2458 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2459 pub struct ClosureOutlivesRequirement<'tcx> {
2460 // This region or type ...
2461 pub subject: ClosureOutlivesSubject<'tcx>,
2463 // .. must outlive this one.
2464 pub outlived_free_region: ty::RegionVid,
2466 // If not, report an error here.
2467 pub blame_span: Span,
2470 /// The subject of a ClosureOutlivesRequirement -- that is, the thing
2471 /// that must outlive some region.
2472 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2473 pub enum ClosureOutlivesSubject<'tcx> {
2474 /// Subject is a type, typically a type parameter, but could also
2475 /// be a projection. Indicates a requirement like `T: 'a` being
2476 /// passed to the caller, where the type here is `T`.
2478 /// The type here is guaranteed not to contain any free regions at
2482 /// Subject is a free region from the closure. Indicates a requirement
2483 /// like `'a: 'b` being passed to the caller; the region here is `'a`.
2484 Region(ty::RegionVid),
2488 * TypeFoldable implementations for MIR types
2491 CloneTypeFoldableAndLiftImpls! {
2498 SourceScopeLocalData,
2501 BraceStructTypeFoldableImpl! {
2502 impl<'tcx> TypeFoldable<'tcx> for Mir<'tcx> {
2505 source_scope_local_data,
2519 BraceStructTypeFoldableImpl! {
2520 impl<'tcx> TypeFoldable<'tcx> for GeneratorLayout<'tcx> {
2525 BraceStructTypeFoldableImpl! {
2526 impl<'tcx> TypeFoldable<'tcx> for LocalDecl<'tcx> {
2537 BraceStructTypeFoldableImpl! {
2538 impl<'tcx> TypeFoldable<'tcx> for BasicBlockData<'tcx> {
2545 BraceStructTypeFoldableImpl! {
2546 impl<'tcx> TypeFoldable<'tcx> for ValidationOperand<'tcx, Place<'tcx>> {
2547 place, ty, re, mutbl
2551 BraceStructTypeFoldableImpl! {
2552 impl<'tcx> TypeFoldable<'tcx> for Statement<'tcx> {
2557 EnumTypeFoldableImpl! {
2558 impl<'tcx> TypeFoldable<'tcx> for StatementKind<'tcx> {
2559 (StatementKind::Assign)(a, b),
2560 (StatementKind::ReadForMatch)(place),
2561 (StatementKind::SetDiscriminant) { place, variant_index },
2562 (StatementKind::StorageLive)(a),
2563 (StatementKind::StorageDead)(a),
2564 (StatementKind::InlineAsm) { asm, outputs, inputs },
2565 (StatementKind::Validate)(a, b),
2566 (StatementKind::EndRegion)(a),
2567 (StatementKind::UserAssertTy)(a, b),
2568 (StatementKind::Nop),
2572 EnumTypeFoldableImpl! {
2573 impl<'tcx, T> TypeFoldable<'tcx> for ClearCrossCrate<T> {
2574 (ClearCrossCrate::Clear),
2575 (ClearCrossCrate::Set)(a),
2576 } where T: TypeFoldable<'tcx>
2579 impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
2580 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2581 use mir::TerminatorKind::*;
2583 let kind = match self.kind {
2584 Goto { target } => Goto { target: target },
2591 discr: discr.fold_with(folder),
2592 switch_ty: switch_ty.fold_with(folder),
2593 values: values.clone(),
2594 targets: targets.clone(),
2601 location: location.fold_with(folder),
2610 } => DropAndReplace {
2611 location: location.fold_with(folder),
2612 value: value.fold_with(folder),
2621 value: value.fold_with(folder),
2631 let dest = destination
2633 .map(|&(ref loc, dest)| (loc.fold_with(folder), dest));
2636 func: func.fold_with(folder),
2637 args: args.fold_with(folder),
2649 let msg = if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
2650 EvalErrorKind::BoundsCheck {
2651 len: len.fold_with(folder),
2652 index: index.fold_with(folder),
2658 cond: cond.fold_with(folder),
2665 GeneratorDrop => GeneratorDrop,
2669 Unreachable => Unreachable,
2672 ref imaginary_targets,
2675 imaginary_targets: imaginary_targets.clone(),
2686 source_info: self.source_info,
2691 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2692 use mir::TerminatorKind::*;
2699 } => discr.visit_with(visitor) || switch_ty.visit_with(visitor),
2700 Drop { ref location, .. } => location.visit_with(visitor),
2705 } => location.visit_with(visitor) || value.visit_with(visitor),
2706 Yield { ref value, .. } => value.visit_with(visitor),
2713 let dest = if let Some((ref loc, _)) = *destination {
2714 loc.visit_with(visitor)
2718 dest || func.visit_with(visitor) || args.visit_with(visitor)
2721 ref cond, ref msg, ..
2723 if cond.visit_with(visitor) {
2724 if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
2725 len.visit_with(visitor) || index.visit_with(visitor)
2740 | FalseUnwind { .. } => false,
2745 impl<'tcx> TypeFoldable<'tcx> for Place<'tcx> {
2746 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2748 &Place::Projection(ref p) => Place::Projection(p.fold_with(folder)),
2753 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2754 if let &Place::Projection(ref p) = self {
2755 p.visit_with(visitor)
2762 impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
2763 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2766 Use(ref op) => Use(op.fold_with(folder)),
2767 Repeat(ref op, len) => Repeat(op.fold_with(folder), len),
2768 Ref(region, bk, ref place) => {
2769 Ref(region.fold_with(folder), bk, place.fold_with(folder))
2771 Len(ref place) => Len(place.fold_with(folder)),
2772 Cast(kind, ref op, ty) => Cast(kind, op.fold_with(folder), ty.fold_with(folder)),
2773 BinaryOp(op, ref rhs, ref lhs) => {
2774 BinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
2776 CheckedBinaryOp(op, ref rhs, ref lhs) => {
2777 CheckedBinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
2779 UnaryOp(op, ref val) => UnaryOp(op, val.fold_with(folder)),
2780 Discriminant(ref place) => Discriminant(place.fold_with(folder)),
2781 NullaryOp(op, ty) => NullaryOp(op, ty.fold_with(folder)),
2782 Aggregate(ref kind, ref fields) => {
2783 let kind = box match **kind {
2784 AggregateKind::Array(ty) => AggregateKind::Array(ty.fold_with(folder)),
2785 AggregateKind::Tuple => AggregateKind::Tuple,
2786 AggregateKind::Adt(def, v, substs, n) => {
2787 AggregateKind::Adt(def, v, substs.fold_with(folder), n)
2789 AggregateKind::Closure(id, substs) => {
2790 AggregateKind::Closure(id, substs.fold_with(folder))
2792 AggregateKind::Generator(id, substs, movablity) => {
2793 AggregateKind::Generator(id, substs.fold_with(folder), movablity)
2796 Aggregate(kind, fields.fold_with(folder))
2801 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2804 Use(ref op) => op.visit_with(visitor),
2805 Repeat(ref op, _) => op.visit_with(visitor),
2806 Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor),
2807 Len(ref place) => place.visit_with(visitor),
2808 Cast(_, ref op, ty) => op.visit_with(visitor) || ty.visit_with(visitor),
2809 BinaryOp(_, ref rhs, ref lhs) | CheckedBinaryOp(_, ref rhs, ref lhs) => {
2810 rhs.visit_with(visitor) || lhs.visit_with(visitor)
2812 UnaryOp(_, ref val) => val.visit_with(visitor),
2813 Discriminant(ref place) => place.visit_with(visitor),
2814 NullaryOp(_, ty) => ty.visit_with(visitor),
2815 Aggregate(ref kind, ref fields) => {
2817 AggregateKind::Array(ty) => ty.visit_with(visitor),
2818 AggregateKind::Tuple => false,
2819 AggregateKind::Adt(_, _, substs, _) => substs.visit_with(visitor),
2820 AggregateKind::Closure(_, substs) => substs.visit_with(visitor),
2821 AggregateKind::Generator(_, substs, _) => substs.visit_with(visitor),
2822 }) || fields.visit_with(visitor)
2828 impl<'tcx> TypeFoldable<'tcx> for Operand<'tcx> {
2829 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2831 Operand::Copy(ref place) => Operand::Copy(place.fold_with(folder)),
2832 Operand::Move(ref place) => Operand::Move(place.fold_with(folder)),
2833 Operand::Constant(ref c) => Operand::Constant(c.fold_with(folder)),
2837 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2839 Operand::Copy(ref place) | Operand::Move(ref place) => place.visit_with(visitor),
2840 Operand::Constant(ref c) => c.visit_with(visitor),
2845 impl<'tcx, B, V, T> TypeFoldable<'tcx> for Projection<'tcx, B, V, T>
2847 B: TypeFoldable<'tcx>,
2848 V: TypeFoldable<'tcx>,
2849 T: TypeFoldable<'tcx>,
2851 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2852 use mir::ProjectionElem::*;
2854 let base = self.base.fold_with(folder);
2855 let elem = match self.elem {
2857 Field(f, ref ty) => Field(f, ty.fold_with(folder)),
2858 Index(ref v) => Index(v.fold_with(folder)),
2859 ref elem => elem.clone(),
2862 Projection { base, elem }
2865 fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool {
2866 use mir::ProjectionElem::*;
2868 self.base.visit_with(visitor) || match self.elem {
2869 Field(_, ref ty) => ty.visit_with(visitor),
2870 Index(ref v) => v.visit_with(visitor),
2876 impl<'tcx> TypeFoldable<'tcx> for Field {
2877 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _: &mut F) -> Self {
2880 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
2885 impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> {
2886 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2888 span: self.span.clone(),
2889 ty: self.ty.fold_with(folder),
2890 literal: self.literal.fold_with(folder),
2893 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2894 self.ty.visit_with(visitor) || self.literal.visit_with(visitor)
2898 impl<'tcx> TypeFoldable<'tcx> for Literal<'tcx> {
2899 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2901 Literal::Value { value } => Literal::Value {
2902 value: value.fold_with(folder),
2904 Literal::Promoted { index } => Literal::Promoted { index },
2907 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2909 Literal::Value { value } => value.visit_with(visitor),
2910 Literal::Promoted { .. } => false,