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::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> ClearCrossCrate<T> {
384 pub fn assert_crate_local(self) -> T {
386 ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"),
387 ClearCrossCrate::Set(v) => v,
392 impl<T: serialize::Encodable> serialize::UseSpecializedEncodable for ClearCrossCrate<T> {}
393 impl<T: serialize::Decodable> serialize::UseSpecializedDecodable for ClearCrossCrate<T> {}
395 /// Grouped information about the source code origin of a MIR entity.
396 /// Intended to be inspected by diagnostics and debuginfo.
397 /// Most passes can work with it as a whole, within a single function.
398 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
399 pub struct SourceInfo {
400 /// Source span for the AST pertaining to this MIR entity.
403 /// The source scope, keeping track of which bindings can be
404 /// seen by debuginfo, active lint levels, `unsafe {...}`, etc.
405 pub scope: SourceScope,
408 ///////////////////////////////////////////////////////////////////////////
409 // Mutability and borrow kinds
411 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
412 pub enum Mutability {
417 impl From<Mutability> for hir::Mutability {
418 fn from(m: Mutability) -> Self {
420 Mutability::Mut => hir::MutMutable,
421 Mutability::Not => hir::MutImmutable,
426 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
427 pub enum BorrowKind {
428 /// Data must be immutable and is aliasable.
431 /// Data must be immutable but not aliasable. This kind of borrow
432 /// cannot currently be expressed by the user and is used only in
433 /// implicit closure bindings. It is needed when you the closure
434 /// is borrowing or mutating a mutable referent, e.g.:
436 /// let x: &mut isize = ...;
437 /// let y = || *x += 5;
439 /// If we were to try to translate this closure into a more explicit
440 /// form, we'd encounter an error with the code as written:
442 /// struct Env { x: & &mut isize }
443 /// let x: &mut isize = ...;
444 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
445 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
447 /// This is then illegal because you cannot mutate a `&mut` found
448 /// in an aliasable location. To solve, you'd have to translate with
449 /// an `&mut` borrow:
451 /// struct Env { x: & &mut isize }
452 /// let x: &mut isize = ...;
453 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
454 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
456 /// Now the assignment to `**env.x` is legal, but creating a
457 /// mutable pointer to `x` is not because `x` is not mutable. We
458 /// could fix this by declaring `x` as `let mut x`. This is ok in
459 /// user code, if awkward, but extra weird for closures, since the
460 /// borrow is hidden.
462 /// So we introduce a "unique imm" borrow -- the referent is
463 /// immutable, but not aliasable. This solves the problem. For
464 /// simplicity, we don't give users the way to express this
465 /// borrow, it's just used when translating closures.
468 /// Data is mutable and not aliasable.
470 /// True if this borrow arose from method-call auto-ref
471 /// (i.e. `adjustment::Adjust::Borrow`)
472 allow_two_phase_borrow: bool,
477 pub fn allows_two_phase_borrow(&self) -> bool {
479 BorrowKind::Shared | BorrowKind::Unique => false,
481 allow_two_phase_borrow,
482 } => allow_two_phase_borrow,
487 ///////////////////////////////////////////////////////////////////////////
488 // Variables and temps
492 DEBUG_FORMAT = "_{}",
493 const RETURN_PLACE = 0,
496 /// Classifies locals into categories. See `Mir::local_kind`.
497 #[derive(PartialEq, Eq, Debug)]
499 /// User-declared variable binding
501 /// Compiler-introduced temporary
503 /// Function argument
505 /// Location of function's return value
509 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
510 pub struct VarBindingForm<'tcx> {
511 /// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`?
512 pub binding_mode: ty::BindingMode,
513 /// If an explicit type was provided for this variable binding,
514 /// this holds the source Span of that type.
516 /// NOTE: If you want to change this to a `HirId`, be wary that
517 /// doing so breaks incremental compilation (as of this writing),
518 /// while a `Span` does not cause our tests to fail.
519 pub opt_ty_info: Option<Span>,
520 /// Place of the RHS of the =, or the subject of the `match` where this
521 /// variable is initialized. None in the case of `let PATTERN;`.
522 /// Some((None, ..)) in the case of and `let [mut] x = ...` because
523 /// (a) the right-hand side isn't evaluated as a place expression.
524 /// (b) it gives a way to separate this case from the remaining cases
526 pub opt_match_place: Option<(Option<Place<'tcx>>, Span)>,
529 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
530 pub enum BindingForm<'tcx> {
531 /// This is a binding for a non-`self` binding, or a `self` that has an explicit type.
532 Var(VarBindingForm<'tcx>),
533 /// Binding for a `self`/`&self`/`&mut self` binding where the type is implicit.
537 CloneTypeFoldableAndLiftImpls! { BindingForm<'tcx>, }
539 impl_stable_hash_for!(struct self::VarBindingForm<'tcx> {
545 mod binding_form_impl {
546 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableHasherResult};
547 use ich::StableHashingContext;
549 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
550 fn hash_stable<W: StableHasherResult>(&self,
551 hcx: &mut StableHashingContext<'a>,
552 hasher: &mut StableHasher<W>) {
553 use super::BindingForm::*;
554 ::std::mem::discriminant(self).hash_stable(hcx, hasher);
557 Var(binding) => binding.hash_stable(hcx, hasher),
566 /// This can be a binding declared by the user, a temporary inserted by the compiler, a function
567 /// argument, or the return place.
568 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
569 pub struct LocalDecl<'tcx> {
570 /// `let mut x` vs `let x`.
572 /// Temporaries and the return place are always mutable.
573 pub mutability: Mutability,
575 /// Some(binding_mode) if this corresponds to a user-declared local variable.
577 /// This is solely used for local diagnostics when generating
578 /// warnings/errors when compiling the current crate, and
579 /// therefore it need not be visible across crates. pnkfelix
580 /// currently hypothesized we *need* to wrap this in a
581 /// `ClearCrossCrate` as long as it carries as `HirId`.
582 pub is_user_variable: Option<ClearCrossCrate<BindingForm<'tcx>>>,
584 /// True if this is an internal local
586 /// These locals are not based on types in the source code and are only used
587 /// for a few desugarings at the moment.
589 /// The generator transformation will sanity check the locals which are live
590 /// across a suspension point against the type components of the generator
591 /// which type checking knows are live across a suspension point. We need to
592 /// flag drop flags to avoid triggering this check as they are introduced
595 /// Unsafety checking will also ignore dereferences of these locals,
596 /// so they can be used for raw pointers only used in a desugaring.
598 /// This should be sound because the drop flags are fully algebraic, and
599 /// therefore don't affect the OIBIT or outlives properties of the
603 /// Type of this local.
606 /// Name of the local, used in debuginfo and pretty-printing.
608 /// Note that function arguments can also have this set to `Some(_)`
609 /// to generate better debuginfo.
610 pub name: Option<Name>,
612 /// The *syntactic* (i.e. not visibility) source scope the local is defined
613 /// in. If the local was defined in a let-statement, this
614 /// is *within* the let-statement, rather than outside
617 /// This is needed because the visibility source scope of locals within
618 /// a let-statement is weird.
620 /// The reason is that we want the local to be *within* the let-statement
621 /// for lint purposes, but we want the local to be *after* the let-statement
622 /// for names-in-scope purposes.
624 /// That's it, if we have a let-statement like the one in this
628 /// fn foo(x: &str) {
629 /// #[allow(unused_mut)]
630 /// let mut x: u32 = { // <- one unused mut
631 /// let mut y: u32 = x.parse().unwrap();
638 /// Then, from a lint point of view, the declaration of `x: u32`
639 /// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the
640 /// lint scopes are the same as the AST/HIR nesting.
642 /// However, from a name lookup point of view, the scopes look more like
643 /// as if the let-statements were `match` expressions:
646 /// fn foo(x: &str) {
648 /// match x.parse().unwrap() {
657 /// We care about the name-lookup scopes for debuginfo - if the
658 /// debuginfo instruction pointer is at the call to `x.parse()`, we
659 /// want `x` to refer to `x: &str`, but if it is at the call to
660 /// `drop(x)`, we want it to refer to `x: u32`.
662 /// To allow both uses to work, we need to have more than a single scope
663 /// for a local. We have the `source_info.scope` represent the
664 /// "syntactic" lint scope (with a variable being under its let
665 /// block) while the `visibility_scope` represents the "local variable"
666 /// scope (where the "rest" of a block is under all prior let-statements).
668 /// The end result looks like this:
672 /// │{ argument x: &str }
674 /// │ │{ #[allow(unused_mut] } // this is actually split into 2 scopes
675 /// │ │ // in practice because I'm lazy.
677 /// │ │← x.source_info.scope
678 /// │ │← `x.parse().unwrap()`
680 /// │ │ │← y.source_info.scope
682 /// │ │ │{ let y: u32 }
684 /// │ │ │← y.visibility_scope
687 /// │ │{ let x: u32 }
688 /// │ │← x.visibility_scope
689 /// │ │← `drop(x)` // this accesses `x: u32`
691 pub source_info: SourceInfo,
693 /// Source scope within which the local is visible (for debuginfo)
694 /// (see `source_info` for more details).
695 pub visibility_scope: SourceScope,
698 impl<'tcx> LocalDecl<'tcx> {
699 /// Returns true only if local is a binding that can itself be
700 /// made mutable via the addition of the `mut` keyword, namely
701 /// something like the occurrences of `x` in:
702 /// - `fn foo(x: Type) { ... }`,
704 /// - or `match ... { C(x) => ... }`
705 pub fn can_be_made_mutable(&self) -> bool {
706 match self.is_user_variable {
707 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
708 binding_mode: ty::BindingMode::BindByValue(_),
713 // FIXME: might be able to thread the distinction between
714 // `self`/`mut self`/`&self`/`&mut self` into the
715 // `BindingForm::ImplicitSelf` variant, (and then return
716 // true here for solely the first case).
721 /// Returns true if local is definitely not a `ref ident` or
722 /// `ref mut ident` binding. (Such bindings cannot be made into
723 /// mutable bindings, but the inverse does not necessarily hold).
724 pub fn is_nonref_binding(&self) -> bool {
725 match self.is_user_variable {
726 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
727 binding_mode: ty::BindingMode::BindByValue(_),
732 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf)) => true,
738 /// Create a new `LocalDecl` for a temporary.
740 pub fn new_temp(ty: Ty<'tcx>, span: Span) -> Self {
742 mutability: Mutability::Mut,
745 source_info: SourceInfo {
747 scope: OUTERMOST_SOURCE_SCOPE,
749 visibility_scope: OUTERMOST_SOURCE_SCOPE,
751 is_user_variable: None,
755 /// Create a new `LocalDecl` for a internal temporary.
757 pub fn new_internal(ty: Ty<'tcx>, span: Span) -> Self {
759 mutability: Mutability::Mut,
762 source_info: SourceInfo {
764 scope: OUTERMOST_SOURCE_SCOPE,
766 visibility_scope: OUTERMOST_SOURCE_SCOPE,
768 is_user_variable: None,
772 /// Builds a `LocalDecl` for the return place.
774 /// This must be inserted into the `local_decls` list as the first local.
776 pub fn new_return_place(return_ty: Ty, span: Span) -> LocalDecl {
778 mutability: Mutability::Mut,
780 source_info: SourceInfo {
782 scope: OUTERMOST_SOURCE_SCOPE,
784 visibility_scope: OUTERMOST_SOURCE_SCOPE,
786 name: None, // FIXME maybe we do want some name here?
787 is_user_variable: None,
792 /// A closure capture, with its name and mode.
793 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
794 pub struct UpvarDecl {
795 pub debug_name: Name,
797 /// `HirId` of the captured variable
798 pub var_hir_id: ClearCrossCrate<HirId>,
800 /// If true, the capture is behind a reference.
803 pub mutability: Mutability,
806 ///////////////////////////////////////////////////////////////////////////
809 newtype_index!(BasicBlock { DEBUG_FORMAT = "bb{}" });
812 pub fn start_location(self) -> Location {
820 ///////////////////////////////////////////////////////////////////////////
821 // BasicBlockData and Terminator
823 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
824 pub struct BasicBlockData<'tcx> {
825 /// List of statements in this block.
826 pub statements: Vec<Statement<'tcx>>,
828 /// Terminator for this block.
830 /// NB. This should generally ONLY be `None` during construction.
831 /// Therefore, you should generally access it via the
832 /// `terminator()` or `terminator_mut()` methods. The only
833 /// exception is that certain passes, such as `simplify_cfg`, swap
834 /// out the terminator temporarily with `None` while they continue
835 /// to recurse over the set of basic blocks.
836 pub terminator: Option<Terminator<'tcx>>,
838 /// If true, this block lies on an unwind path. This is used
839 /// during codegen where distinct kinds of basic blocks may be
840 /// generated (particularly for MSVC cleanup). Unwind blocks must
841 /// only branch to other unwind blocks.
842 pub is_cleanup: bool,
845 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
846 pub struct Terminator<'tcx> {
847 pub source_info: SourceInfo,
848 pub kind: TerminatorKind<'tcx>,
851 #[derive(Clone, RustcEncodable, RustcDecodable)]
852 pub enum TerminatorKind<'tcx> {
853 /// block should have one successor in the graph; we jump there
854 Goto { target: BasicBlock },
856 /// operand evaluates to an integer; jump depending on its value
857 /// to one of the targets, and otherwise fallback to `otherwise`
859 /// discriminant value being tested
860 discr: Operand<'tcx>,
862 /// type of value being tested
865 /// Possible values. The locations to branch to in each case
866 /// are found in the corresponding indices from the `targets` vector.
867 values: Cow<'tcx, [u128]>,
869 /// Possible branch sites. The last element of this vector is used
870 /// for the otherwise branch, so targets.len() == values.len() + 1
872 // This invariant is quite non-obvious and also could be improved.
873 // One way to make this invariant is to have something like this instead:
875 // branches: Vec<(ConstInt, BasicBlock)>,
876 // otherwise: Option<BasicBlock> // exhaustive if None
878 // However we’ve decided to keep this as-is until we figure a case
879 // where some other approach seems to be strictly better than other.
880 targets: Vec<BasicBlock>,
883 /// Indicates that the landing pad is finished and unwinding should
884 /// continue. Emitted by build::scope::diverge_cleanup.
887 /// Indicates that the landing pad is finished and that the process
888 /// should abort. Used to prevent unwinding for foreign items.
891 /// Indicates a normal return. The return place should have
892 /// been filled in by now. This should occur at most once.
895 /// Indicates a terminator that can never be reached.
900 location: Place<'tcx>,
902 unwind: Option<BasicBlock>,
905 /// Drop the Place and assign the new value over it. This ensures
906 /// that the assignment to `P` occurs *even if* the destructor for
907 /// place unwinds. Its semantics are best explained by by the
912 /// DropAndReplace(P <- V, goto BB1, unwind BB2)
920 /// Drop(P, goto BB1, unwind BB2)
923 /// // P is now unitialized
927 /// // P is now unitialized -- its dtor panicked
932 location: Place<'tcx>,
933 value: Operand<'tcx>,
935 unwind: Option<BasicBlock>,
938 /// Block ends with a call of a converging function
940 /// The function that’s being called
942 /// Arguments the function is called with.
943 /// These are owned by the callee, which is free to modify them.
944 /// This allows the memory occupied by "by-value" arguments to be
945 /// reused across function calls without duplicating the contents.
946 args: Vec<Operand<'tcx>>,
947 /// Destination for the return value. If some, the call is converging.
948 destination: Option<(Place<'tcx>, BasicBlock)>,
949 /// Cleanups to be done if the call unwinds.
950 cleanup: Option<BasicBlock>,
953 /// Jump to the target if the condition has the expected value,
954 /// otherwise panic with a message and a cleanup target.
958 msg: AssertMessage<'tcx>,
960 cleanup: Option<BasicBlock>,
965 /// The value to return
966 value: Operand<'tcx>,
967 /// Where to resume to
969 /// Cleanup to be done if the generator is dropped at this suspend point
970 drop: Option<BasicBlock>,
973 /// Indicates the end of the dropping of a generator
976 /// A block where control flow only ever takes one real path, but borrowck
977 /// needs to be more conservative.
979 /// The target normal control flow will take
980 real_target: BasicBlock,
981 /// The list of blocks control flow could conceptually take, but won't
983 imaginary_targets: Vec<BasicBlock>,
985 /// A terminator for blocks that only take one path in reality, but where we
986 /// reserve the right to unwind in borrowck, even if it won't happen in practice.
987 /// This can arise in infinite loops with no function calls for example.
989 /// The target normal control flow will take
990 real_target: BasicBlock,
991 /// The imaginary cleanup block link. This particular path will never be taken
992 /// in practice, but in order to avoid fragility we want to always
993 /// consider it in borrowck. We don't want to accept programs which
994 /// pass borrowck only when panic=abort or some assertions are disabled
995 /// due to release vs. debug mode builds. This needs to be an Option because
996 /// of the remove_noop_landing_pads and no_landing_pads passes
997 unwind: Option<BasicBlock>,
1001 pub type Successors<'a> =
1002 iter::Chain<option::IntoIter<&'a BasicBlock>, slice::Iter<'a, BasicBlock>>;
1003 pub type SuccessorsMut<'a> =
1004 iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>;
1006 impl<'tcx> Terminator<'tcx> {
1007 pub fn successors(&self) -> Successors {
1008 self.kind.successors()
1011 pub fn successors_mut(&mut self) -> SuccessorsMut {
1012 self.kind.successors_mut()
1015 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1019 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1020 self.kind.unwind_mut()
1024 impl<'tcx> TerminatorKind<'tcx> {
1025 pub fn if_<'a, 'gcx>(
1026 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1027 cond: Operand<'tcx>,
1030 ) -> TerminatorKind<'tcx> {
1031 static BOOL_SWITCH_FALSE: &'static [u128] = &[0];
1032 TerminatorKind::SwitchInt {
1034 switch_ty: tcx.types.bool,
1035 values: From::from(BOOL_SWITCH_FALSE),
1036 targets: vec![f, t],
1040 pub fn successors(&self) -> Successors {
1041 use self::TerminatorKind::*;
1052 } => None.into_iter().chain(&[]),
1053 Goto { target: ref t }
1056 cleanup: Some(ref t),
1060 destination: Some((_, ref t)),
1087 } => Some(t).into_iter().chain(&[]),
1089 destination: Some((_, ref t)),
1090 cleanup: Some(ref u),
1100 unwind: Some(ref u),
1105 unwind: Some(ref u),
1110 cleanup: Some(ref u),
1115 unwind: Some(ref u),
1116 } => Some(t).into_iter().chain(slice::from_ref(u)),
1117 SwitchInt { ref targets, .. } => None.into_iter().chain(&targets[..]),
1120 ref imaginary_targets,
1121 } => Some(real_target).into_iter().chain(&imaginary_targets[..]),
1125 pub fn successors_mut(&mut self) -> SuccessorsMut {
1126 use self::TerminatorKind::*;
1137 } => None.into_iter().chain(&mut []),
1138 Goto { target: ref mut t }
1141 cleanup: Some(ref mut t),
1145 destination: Some((_, ref mut t)),
1170 real_target: ref mut t,
1172 } => Some(t).into_iter().chain(&mut []),
1174 destination: Some((_, ref mut t)),
1175 cleanup: Some(ref mut u),
1180 drop: Some(ref mut u),
1185 unwind: Some(ref mut u),
1190 unwind: Some(ref mut u),
1195 cleanup: Some(ref mut u),
1199 real_target: ref mut t,
1200 unwind: Some(ref mut u),
1201 } => Some(t).into_iter().chain(slice::from_mut(u)),
1204 } => None.into_iter().chain(&mut targets[..]),
1206 ref mut real_target,
1207 ref mut imaginary_targets,
1208 } => Some(real_target)
1210 .chain(&mut imaginary_targets[..]),
1214 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1216 TerminatorKind::Goto { .. }
1217 | TerminatorKind::Resume
1218 | TerminatorKind::Abort
1219 | TerminatorKind::Return
1220 | TerminatorKind::Unreachable
1221 | TerminatorKind::GeneratorDrop
1222 | TerminatorKind::Yield { .. }
1223 | TerminatorKind::SwitchInt { .. }
1224 | TerminatorKind::FalseEdges { .. } => None,
1225 TerminatorKind::Call {
1226 cleanup: ref unwind,
1229 | TerminatorKind::Assert {
1230 cleanup: ref unwind,
1233 | TerminatorKind::DropAndReplace { ref unwind, .. }
1234 | TerminatorKind::Drop { ref unwind, .. }
1235 | TerminatorKind::FalseUnwind { ref unwind, .. } => Some(unwind),
1239 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1241 TerminatorKind::Goto { .. }
1242 | TerminatorKind::Resume
1243 | TerminatorKind::Abort
1244 | TerminatorKind::Return
1245 | TerminatorKind::Unreachable
1246 | TerminatorKind::GeneratorDrop
1247 | TerminatorKind::Yield { .. }
1248 | TerminatorKind::SwitchInt { .. }
1249 | TerminatorKind::FalseEdges { .. } => None,
1250 TerminatorKind::Call {
1251 cleanup: ref mut unwind,
1254 | TerminatorKind::Assert {
1255 cleanup: ref mut unwind,
1258 | TerminatorKind::DropAndReplace { ref mut unwind, .. }
1259 | TerminatorKind::Drop { ref mut unwind, .. }
1260 | TerminatorKind::FalseUnwind { ref mut unwind, .. } => Some(unwind),
1265 impl<'tcx> BasicBlockData<'tcx> {
1266 pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
1274 /// Accessor for terminator.
1276 /// Terminator may not be None after construction of the basic block is complete. This accessor
1277 /// provides a convenience way to reach the terminator.
1278 pub fn terminator(&self) -> &Terminator<'tcx> {
1279 self.terminator.as_ref().expect("invalid terminator state")
1282 pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
1283 self.terminator.as_mut().expect("invalid terminator state")
1286 pub fn retain_statements<F>(&mut self, mut f: F)
1288 F: FnMut(&mut Statement) -> bool,
1290 for s in &mut self.statements {
1297 pub fn expand_statements<F, I>(&mut self, mut f: F)
1299 F: FnMut(&mut Statement<'tcx>) -> Option<I>,
1300 I: iter::TrustedLen<Item = Statement<'tcx>>,
1302 // Gather all the iterators we'll need to splice in, and their positions.
1303 let mut splices: Vec<(usize, I)> = vec![];
1304 let mut extra_stmts = 0;
1305 for (i, s) in self.statements.iter_mut().enumerate() {
1306 if let Some(mut new_stmts) = f(s) {
1307 if let Some(first) = new_stmts.next() {
1308 // We can already store the first new statement.
1311 // Save the other statements for optimized splicing.
1312 let remaining = new_stmts.size_hint().0;
1314 splices.push((i + 1 + extra_stmts, new_stmts));
1315 extra_stmts += remaining;
1323 // Splice in the new statements, from the end of the block.
1324 // FIXME(eddyb) This could be more efficient with a "gap buffer"
1325 // where a range of elements ("gap") is left uninitialized, with
1326 // splicing adding new elements to the end of that gap and moving
1327 // existing elements from before the gap to the end of the gap.
1328 // For now, this is safe code, emulating a gap but initializing it.
1329 let mut gap = self.statements.len()..self.statements.len() + extra_stmts;
1330 self.statements.resize(
1333 source_info: SourceInfo {
1335 scope: OUTERMOST_SOURCE_SCOPE,
1337 kind: StatementKind::Nop,
1340 for (splice_start, new_stmts) in splices.into_iter().rev() {
1341 let splice_end = splice_start + new_stmts.size_hint().0;
1342 while gap.end > splice_end {
1345 self.statements.swap(gap.start, gap.end);
1347 self.statements.splice(splice_start..splice_end, new_stmts);
1348 gap.end = splice_start;
1352 pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
1353 if index < self.statements.len() {
1354 &self.statements[index]
1361 impl<'tcx> Debug for TerminatorKind<'tcx> {
1362 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1363 self.fmt_head(fmt)?;
1364 let successor_count = self.successors().count();
1365 let labels = self.fmt_successor_labels();
1366 assert_eq!(successor_count, labels.len());
1368 match successor_count {
1371 1 => write!(fmt, " -> {:?}", self.successors().nth(0).unwrap()),
1374 write!(fmt, " -> [")?;
1375 for (i, target) in self.successors().enumerate() {
1379 write!(fmt, "{}: {:?}", labels[i], target)?;
1387 impl<'tcx> TerminatorKind<'tcx> {
1388 /// Write the "head" part of the terminator; that is, its name and the data it uses to pick the
1389 /// successor basic block, if any. The only information not included is the list of possible
1390 /// successors, which may be rendered differently between the text and the graphviz format.
1391 pub fn fmt_head<W: Write>(&self, fmt: &mut W) -> fmt::Result {
1392 use self::TerminatorKind::*;
1394 Goto { .. } => write!(fmt, "goto"),
1396 discr: ref place, ..
1397 } => write!(fmt, "switchInt({:?})", place),
1398 Return => write!(fmt, "return"),
1399 GeneratorDrop => write!(fmt, "generator_drop"),
1400 Resume => write!(fmt, "resume"),
1401 Abort => write!(fmt, "abort"),
1402 Yield { ref value, .. } => write!(fmt, "_1 = suspend({:?})", value),
1403 Unreachable => write!(fmt, "unreachable"),
1404 Drop { ref location, .. } => write!(fmt, "drop({:?})", location),
1409 } => write!(fmt, "replace({:?} <- {:?})", location, value),
1416 if let Some((ref destination, _)) = *destination {
1417 write!(fmt, "{:?} = ", destination)?;
1419 write!(fmt, "{:?}(", func)?;
1420 for (index, arg) in args.iter().enumerate() {
1424 write!(fmt, "{:?}", arg)?;
1434 write!(fmt, "assert(")?;
1438 write!(fmt, "{:?}, \"{:?}\")", cond, msg)
1440 FalseEdges { .. } => write!(fmt, "falseEdges"),
1441 FalseUnwind { .. } => write!(fmt, "falseUnwind"),
1445 /// Return the list of labels for the edges to the successor basic blocks.
1446 pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> {
1447 use self::TerminatorKind::*;
1449 Return | Resume | Abort | Unreachable | GeneratorDrop => vec![],
1450 Goto { .. } => vec!["".into()],
1456 let size = ty::tls::with(|tcx| {
1457 let param_env = ty::ParamEnv::empty();
1458 let switch_ty = tcx.lift_to_global(&switch_ty).unwrap();
1459 tcx.layout_of(param_env.and(switch_ty)).unwrap().size
1464 let mut s = String::new();
1466 Value::Scalar(Scalar::Bits {
1468 defined: size.bits() as u8,
1475 .chain(iter::once(String::from("otherwise").into()))
1479 destination: Some(_),
1482 } => vec!["return".into_cow(), "unwind".into_cow()],
1484 destination: Some(_),
1487 } => vec!["return".into_cow()],
1492 } => vec!["unwind".into_cow()],
1498 Yield { drop: Some(_), .. } => vec!["resume".into_cow(), "drop".into_cow()],
1499 Yield { drop: None, .. } => vec!["resume".into_cow()],
1500 DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => {
1501 vec!["return".into_cow()]
1508 } => vec!["return".into_cow(), "unwind".into_cow()],
1509 Assert { cleanup: None, .. } => vec!["".into()],
1510 Assert { .. } => vec!["success".into_cow(), "unwind".into_cow()],
1512 ref imaginary_targets,
1515 let mut l = vec!["real".into()];
1516 l.resize(imaginary_targets.len() + 1, "imaginary".into());
1521 } => vec!["real".into(), "cleanup".into()],
1522 FalseUnwind { unwind: None, .. } => vec!["real".into()],
1527 ///////////////////////////////////////////////////////////////////////////
1530 #[derive(Clone, RustcEncodable, RustcDecodable)]
1531 pub struct Statement<'tcx> {
1532 pub source_info: SourceInfo,
1533 pub kind: StatementKind<'tcx>,
1536 impl<'tcx> Statement<'tcx> {
1537 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
1538 /// invalidating statement indices in `Location`s.
1539 pub fn make_nop(&mut self) {
1540 self.kind = StatementKind::Nop
1543 /// Changes a statement to a nop and returns the original statement.
1544 pub fn replace_nop(&mut self) -> Self {
1546 source_info: self.source_info,
1547 kind: mem::replace(&mut self.kind, StatementKind::Nop),
1552 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1553 pub enum StatementKind<'tcx> {
1554 /// Write the RHS Rvalue to the LHS Place.
1555 Assign(Place<'tcx>, Rvalue<'tcx>),
1557 /// This represents all the reading that a pattern match may do
1558 /// (e.g. inspecting constants and discriminant values).
1559 ReadForMatch(Place<'tcx>),
1561 /// Write the discriminant for a variant to the enum Place.
1564 variant_index: usize,
1567 /// Start a live range for the storage of the local.
1570 /// End the current live range for the storage of the local.
1573 /// Execute a piece of inline Assembly.
1575 asm: Box<InlineAsm>,
1576 outputs: Vec<Place<'tcx>>,
1577 inputs: Vec<Operand<'tcx>>,
1580 /// Assert the given places to be valid inhabitants of their type. These statements are
1581 /// currently only interpreted by miri and only generated when "-Z mir-emit-validate" is passed.
1582 /// See <https://internals.rust-lang.org/t/types-as-contracts/5562/73> for more details.
1583 Validate(ValidationOp, Vec<ValidationOperand<'tcx, Place<'tcx>>>),
1585 /// Mark one terminating point of a region scope (i.e. static region).
1586 /// (The starting point(s) arise implicitly from borrows.)
1587 EndRegion(region::Scope),
1589 /// Encodes a user's type assertion. These need to be preserved intact so that NLL can respect
1590 /// them. For example:
1592 /// let (a, b): (T, U) = y;
1594 /// Here we would insert a `UserAssertTy<(T, U)>(y)` instruction to check that the type of `y`
1595 /// is the right thing.
1597 /// `CanonicalTy` is used to capture "inference variables" from the user's types. For example:
1599 /// let x: Vec<_> = ...;
1600 /// let y: &u32 = ...;
1602 /// would result in `Vec<?0>` and `&'?0 u32` respectively (where `?0` is a canonicalized
1604 UserAssertTy(CanonicalTy<'tcx>, Local),
1606 /// No-op. Useful for deleting instructions without affecting statement indices.
1610 /// The `ValidationOp` describes what happens with each of the operands of a
1611 /// `Validate` statement.
1612 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, PartialEq, Eq)]
1613 pub enum ValidationOp {
1614 /// Recursively traverse the place following the type and validate that all type
1615 /// invariants are maintained. Furthermore, acquire exclusive/read-only access to the
1616 /// memory reachable from the place.
1618 /// Recursive traverse the *mutable* part of the type and relinquish all exclusive
1621 /// Recursive traverse the *mutable* part of the type and relinquish all exclusive
1622 /// access *until* the given region ends. Then, access will be recovered.
1623 Suspend(region::Scope),
1626 impl Debug for ValidationOp {
1627 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1628 use self::ValidationOp::*;
1630 Acquire => write!(fmt, "Acquire"),
1631 Release => write!(fmt, "Release"),
1632 // (reuse lifetime rendering policy from ppaux.)
1633 Suspend(ref ce) => write!(fmt, "Suspend({})", ty::ReScope(*ce)),
1638 // This is generic so that it can be reused by miri
1639 #[derive(Clone, Hash, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1640 pub struct ValidationOperand<'tcx, T> {
1643 pub re: Option<region::Scope>,
1644 pub mutbl: hir::Mutability,
1647 impl<'tcx, T: Debug> Debug for ValidationOperand<'tcx, T> {
1648 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1649 write!(fmt, "{:?}: {:?}", self.place, self.ty)?;
1650 if let Some(ce) = self.re {
1651 // (reuse lifetime rendering policy from ppaux.)
1652 write!(fmt, "/{}", ty::ReScope(ce))?;
1654 if let hir::MutImmutable = self.mutbl {
1655 write!(fmt, " (imm)")?;
1661 impl<'tcx> Debug for Statement<'tcx> {
1662 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1663 use self::StatementKind::*;
1665 Assign(ref place, ref rv) => write!(fmt, "{:?} = {:?}", place, rv),
1666 ReadForMatch(ref place) => write!(fmt, "ReadForMatch({:?})", place),
1667 // (reuse lifetime rendering policy from ppaux.)
1668 EndRegion(ref ce) => write!(fmt, "EndRegion({})", ty::ReScope(*ce)),
1669 Validate(ref op, ref places) => write!(fmt, "Validate({:?}, {:?})", op, places),
1670 StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place),
1671 StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place),
1675 } => write!(fmt, "discriminant({:?}) = {:?}", place, variant_index),
1680 } => write!(fmt, "asm!({:?} : {:?} : {:?})", asm, outputs, inputs),
1681 UserAssertTy(ref c_ty, ref local) => {
1682 write!(fmt, "UserAssertTy({:?}, {:?})", c_ty, local)
1684 Nop => write!(fmt, "nop"),
1689 ///////////////////////////////////////////////////////////////////////////
1692 /// A path to a value; something that can be evaluated without
1693 /// changing or disturbing program state.
1694 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1695 pub enum Place<'tcx> {
1699 /// static or static mut variable
1700 Static(Box<Static<'tcx>>),
1702 /// projection out of a place (access a field, deref a pointer, etc)
1703 Projection(Box<PlaceProjection<'tcx>>),
1706 /// The def-id of a static, along with its normalized type (which is
1707 /// stored to avoid requiring normalization when reading MIR).
1708 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1709 pub struct Static<'tcx> {
1714 impl_stable_hash_for!(struct Static<'tcx> {
1719 /// The `Projection` data structure defines things of the form `B.x`
1720 /// or `*B` or `B[index]`. Note that it is parameterized because it is
1721 /// shared between `Constant` and `Place`. See the aliases
1722 /// `PlaceProjection` etc below.
1723 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1724 pub struct Projection<'tcx, B, V, T> {
1726 pub elem: ProjectionElem<'tcx, V, T>,
1729 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1730 pub enum ProjectionElem<'tcx, V, T> {
1735 /// These indices are generated by slice patterns. Easiest to explain
1739 /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
1740 /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
1741 /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
1742 /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
1745 /// index or -index (in Python terms), depending on from_end
1747 /// thing being indexed must be at least this long
1749 /// counting backwards from end?
1753 /// These indices are generated by slice patterns.
1755 /// slice[from:-to] in Python terms.
1761 /// "Downcast" to a variant of an ADT. Currently, we only introduce
1762 /// this for ADTs with more than one variant. It may be better to
1763 /// just introduce it always, or always for enums.
1764 Downcast(&'tcx AdtDef, usize),
1767 /// Alias for projections as they appear in places, where the base is a place
1768 /// and the index is a local.
1769 pub type PlaceProjection<'tcx> = Projection<'tcx, Place<'tcx>, Local, Ty<'tcx>>;
1771 /// Alias for projections as they appear in places, where the base is a place
1772 /// and the index is a local.
1773 pub type PlaceElem<'tcx> = ProjectionElem<'tcx, Local, Ty<'tcx>>;
1775 newtype_index!(Field { DEBUG_FORMAT = "field[{}]" });
1777 impl<'tcx> Place<'tcx> {
1778 pub fn field(self, f: Field, ty: Ty<'tcx>) -> Place<'tcx> {
1779 self.elem(ProjectionElem::Field(f, ty))
1782 pub fn deref(self) -> Place<'tcx> {
1783 self.elem(ProjectionElem::Deref)
1786 pub fn downcast(self, adt_def: &'tcx AdtDef, variant_index: usize) -> Place<'tcx> {
1787 self.elem(ProjectionElem::Downcast(adt_def, variant_index))
1790 pub fn index(self, index: Local) -> Place<'tcx> {
1791 self.elem(ProjectionElem::Index(index))
1794 pub fn elem(self, elem: PlaceElem<'tcx>) -> Place<'tcx> {
1795 Place::Projection(Box::new(PlaceProjection { base: self, elem }))
1799 impl<'tcx> Debug for Place<'tcx> {
1800 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1804 Local(id) => write!(fmt, "{:?}", id),
1805 Static(box self::Static { def_id, ty }) => write!(
1808 ty::tls::with(|tcx| tcx.item_path_str(def_id)),
1811 Projection(ref data) => match data.elem {
1812 ProjectionElem::Downcast(ref adt_def, index) => {
1813 write!(fmt, "({:?} as {})", data.base, adt_def.variants[index].name)
1815 ProjectionElem::Deref => write!(fmt, "(*{:?})", data.base),
1816 ProjectionElem::Field(field, ty) => {
1817 write!(fmt, "({:?}.{:?}: {:?})", data.base, field.index(), ty)
1819 ProjectionElem::Index(ref index) => write!(fmt, "{:?}[{:?}]", data.base, index),
1820 ProjectionElem::ConstantIndex {
1824 } => write!(fmt, "{:?}[{:?} of {:?}]", data.base, offset, min_length),
1825 ProjectionElem::ConstantIndex {
1829 } => write!(fmt, "{:?}[-{:?} of {:?}]", data.base, offset, min_length),
1830 ProjectionElem::Subslice { from, to } if to == 0 => {
1831 write!(fmt, "{:?}[{:?}:]", data.base, from)
1833 ProjectionElem::Subslice { from, to } if from == 0 => {
1834 write!(fmt, "{:?}[:-{:?}]", data.base, to)
1836 ProjectionElem::Subslice { from, to } => {
1837 write!(fmt, "{:?}[{:?}:-{:?}]", data.base, from, to)
1844 ///////////////////////////////////////////////////////////////////////////
1847 newtype_index!(SourceScope
1849 DEBUG_FORMAT = "scope[{}]",
1850 const OUTERMOST_SOURCE_SCOPE = 0,
1853 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1854 pub struct SourceScopeData {
1856 pub parent_scope: Option<SourceScope>,
1859 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1860 pub struct SourceScopeLocalData {
1861 /// A NodeId with lint levels equivalent to this scope's lint levels.
1862 pub lint_root: ast::NodeId,
1863 /// The unsafe block that contains this node.
1867 ///////////////////////////////////////////////////////////////////////////
1870 /// These are values that can appear inside an rvalue (or an index
1871 /// place). They are intentionally limited to prevent rvalues from
1872 /// being nested in one another.
1873 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
1874 pub enum Operand<'tcx> {
1875 /// Copy: The value must be available for use afterwards.
1877 /// This implies that the type of the place must be `Copy`; this is true
1878 /// by construction during build, but also checked by the MIR type checker.
1880 /// Move: The value (including old borrows of it) will not be used again.
1882 /// Safe for values of all types (modulo future developments towards `?Move`).
1883 /// Correct usage patterns are enforced by the borrow checker for safe code.
1884 /// `Copy` may be converted to `Move` to enable "last-use" optimizations.
1886 Constant(Box<Constant<'tcx>>),
1889 impl<'tcx> Debug for Operand<'tcx> {
1890 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1891 use self::Operand::*;
1893 Constant(ref a) => write!(fmt, "{:?}", a),
1894 Copy(ref place) => write!(fmt, "{:?}", place),
1895 Move(ref place) => write!(fmt, "move {:?}", place),
1900 impl<'tcx> Operand<'tcx> {
1901 pub fn function_handle<'a>(
1902 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1904 substs: &'tcx Substs<'tcx>,
1907 let ty = tcx.type_of(def_id).subst(tcx, substs);
1908 Operand::Constant(box Constant {
1911 literal: Literal::Value {
1912 value: ty::Const::zero_sized(tcx, ty),
1917 pub fn to_copy(&self) -> Self {
1919 Operand::Copy(_) | Operand::Constant(_) => self.clone(),
1920 Operand::Move(ref place) => Operand::Copy(place.clone()),
1925 ///////////////////////////////////////////////////////////////////////////
1928 #[derive(Clone, RustcEncodable, RustcDecodable)]
1929 pub enum Rvalue<'tcx> {
1930 /// x (either a move or copy, depending on type of x)
1934 Repeat(Operand<'tcx>, u64),
1937 Ref(Region<'tcx>, BorrowKind, Place<'tcx>),
1939 /// length of a [X] or [X;n] value
1942 Cast(CastKind, Operand<'tcx>, Ty<'tcx>),
1944 BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
1945 CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
1947 NullaryOp(NullOp, Ty<'tcx>),
1948 UnaryOp(UnOp, Operand<'tcx>),
1950 /// Read the discriminant of an ADT.
1952 /// Undefined (i.e. no effort is made to make it defined, but there’s no reason why it cannot
1953 /// be defined to return, say, a 0) if ADT is not an enum.
1954 Discriminant(Place<'tcx>),
1956 /// Create an aggregate value, like a tuple or struct. This is
1957 /// only needed because we want to distinguish `dest = Foo { x:
1958 /// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case
1959 /// that `Foo` has a destructor. These rvalues can be optimized
1960 /// away after type-checking and before lowering.
1961 Aggregate(Box<AggregateKind<'tcx>>, Vec<Operand<'tcx>>),
1964 #[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1968 /// Convert unique, zero-sized type for a fn to fn()
1971 /// Convert non capturing closure to fn()
1974 /// Convert safe fn() to unsafe fn()
1977 /// "Unsize" -- convert a thin-or-fat pointer to a fat pointer.
1978 /// codegen must figure out the details once full monomorphization
1979 /// is known. For example, this could be used to cast from a
1980 /// `&[i32;N]` to a `&[i32]`, or a `Box<T>` to a `Box<Trait>`
1981 /// (presuming `T: Trait`).
1985 #[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1986 pub enum AggregateKind<'tcx> {
1987 /// The type is of the element
1991 /// The second field is the variant index. It's equal to 0 for struct
1992 /// and union expressions. The fourth field is
1993 /// active field number and is present only for union expressions
1994 /// -- e.g. for a union expression `SomeUnion { c: .. }`, the
1995 /// active field index would identity the field `c`
1996 Adt(&'tcx AdtDef, usize, &'tcx Substs<'tcx>, Option<usize>),
1998 Closure(DefId, ClosureSubsts<'tcx>),
1999 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
2002 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2004 /// The `+` operator (addition)
2006 /// The `-` operator (subtraction)
2008 /// The `*` operator (multiplication)
2010 /// The `/` operator (division)
2012 /// The `%` operator (modulus)
2014 /// The `^` operator (bitwise xor)
2016 /// The `&` operator (bitwise and)
2018 /// The `|` operator (bitwise or)
2020 /// The `<<` operator (shift left)
2022 /// The `>>` operator (shift right)
2024 /// The `==` operator (equality)
2026 /// The `<` operator (less than)
2028 /// The `<=` operator (less than or equal to)
2030 /// The `!=` operator (not equal to)
2032 /// The `>=` operator (greater than or equal to)
2034 /// The `>` operator (greater than)
2036 /// The `ptr.offset` operator
2041 pub fn is_checkable(self) -> bool {
2044 Add | Sub | Mul | Shl | Shr => true,
2050 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2052 /// Return the size of a value of that type
2054 /// Create a new uninitialized box for a value of that type
2058 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2060 /// The `!` operator for logical inversion
2062 /// The `-` operator for negation
2066 impl<'tcx> Debug for Rvalue<'tcx> {
2067 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2068 use self::Rvalue::*;
2071 Use(ref place) => write!(fmt, "{:?}", place),
2072 Repeat(ref a, ref b) => write!(fmt, "[{:?}; {:?}]", a, b),
2073 Len(ref a) => write!(fmt, "Len({:?})", a),
2074 Cast(ref kind, ref place, ref ty) => {
2075 write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind)
2077 BinaryOp(ref op, ref a, ref b) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
2078 CheckedBinaryOp(ref op, ref a, ref b) => {
2079 write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b)
2081 UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
2082 Discriminant(ref place) => write!(fmt, "discriminant({:?})", place),
2083 NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
2084 Ref(region, borrow_kind, ref place) => {
2085 let kind_str = match borrow_kind {
2086 BorrowKind::Shared => "",
2087 BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ",
2090 // When printing regions, add trailing space if necessary.
2091 let region = if ppaux::verbose() || ppaux::identify_regions() {
2092 let mut region = format!("{}", region);
2093 if region.len() > 0 {
2098 // Do not even print 'static
2101 write!(fmt, "&{}{}{:?}", region, kind_str, place)
2104 Aggregate(ref kind, ref places) => {
2105 fn fmt_tuple(fmt: &mut Formatter, places: &[Operand]) -> fmt::Result {
2106 let mut tuple_fmt = fmt.debug_tuple("");
2107 for place in places {
2108 tuple_fmt.field(place);
2114 AggregateKind::Array(_) => write!(fmt, "{:?}", places),
2116 AggregateKind::Tuple => match places.len() {
2117 0 => write!(fmt, "()"),
2118 1 => write!(fmt, "({:?},)", places[0]),
2119 _ => fmt_tuple(fmt, places),
2122 AggregateKind::Adt(adt_def, variant, substs, _) => {
2123 let variant_def = &adt_def.variants[variant];
2125 ppaux::parameterized(fmt, substs, variant_def.did, &[])?;
2127 match variant_def.ctor_kind {
2128 CtorKind::Const => Ok(()),
2129 CtorKind::Fn => fmt_tuple(fmt, places),
2130 CtorKind::Fictive => {
2131 let mut struct_fmt = fmt.debug_struct("");
2132 for (field, place) in variant_def.fields.iter().zip(places) {
2133 struct_fmt.field(&field.ident.as_str(), place);
2140 AggregateKind::Closure(def_id, _) => ty::tls::with(|tcx| {
2141 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2142 let name = if tcx.sess.opts.debugging_opts.span_free_formats {
2143 format!("[closure@{:?}]", node_id)
2145 format!("[closure@{:?}]", tcx.hir.span(node_id))
2147 let mut struct_fmt = fmt.debug_struct(&name);
2149 tcx.with_freevars(node_id, |freevars| {
2150 for (freevar, place) in freevars.iter().zip(places) {
2151 let var_name = tcx.hir.name(freevar.var_id());
2152 struct_fmt.field(&var_name.as_str(), place);
2158 write!(fmt, "[closure]")
2162 AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
2163 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2164 let name = format!("[generator@{:?}]", tcx.hir.span(node_id));
2165 let mut struct_fmt = fmt.debug_struct(&name);
2167 tcx.with_freevars(node_id, |freevars| {
2168 for (freevar, place) in freevars.iter().zip(places) {
2169 let var_name = tcx.hir.name(freevar.var_id());
2170 struct_fmt.field(&var_name.as_str(), place);
2172 struct_fmt.field("$state", &places[freevars.len()]);
2173 for i in (freevars.len() + 1)..places.len() {
2175 .field(&format!("${}", i - freevars.len() - 1), &places[i]);
2181 write!(fmt, "[generator]")
2190 ///////////////////////////////////////////////////////////////////////////
2193 /// Two constants are equal if they are the same constant. Note that
2194 /// this does not necessarily mean that they are "==" in Rust -- in
2195 /// particular one must be wary of `NaN`!
2197 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2198 pub struct Constant<'tcx> {
2201 pub literal: Literal<'tcx>,
2204 newtype_index!(Promoted { DEBUG_FORMAT = "promoted[{}]" });
2206 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2207 pub enum Literal<'tcx> {
2209 value: &'tcx ty::Const<'tcx>,
2212 // Index into the `promoted` vector of `Mir`.
2217 impl<'tcx> Debug for Constant<'tcx> {
2218 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2219 write!(fmt, "{:?}", self.literal)
2223 impl<'tcx> Debug for Literal<'tcx> {
2224 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
2225 use self::Literal::*;
2227 Value { value } => {
2228 write!(fmt, "const ")?;
2229 fmt_const_val(fmt, value)
2231 Promoted { index } => write!(fmt, "{:?}", index),
2236 /// Write a `ConstValue` in a way closer to the original source code than the `Debug` output.
2237 pub fn fmt_const_val<W: Write>(fmt: &mut W, const_val: &ty::Const) -> fmt::Result {
2238 if let Some(value) = const_val.to_byval_value() {
2239 print_miri_value(value, const_val.ty, fmt)
2241 write!(fmt, "{:?}:{}", const_val.val, const_val.ty)
2245 pub fn print_miri_value<W: Write>(value: Value, ty: Ty, f: &mut W) -> fmt::Result {
2246 use ty::TypeVariants::*;
2247 match (value, &ty.sty) {
2248 (Value::Scalar(Scalar::Bits { bits: 0, .. }), &TyBool) => write!(f, "false"),
2249 (Value::Scalar(Scalar::Bits { bits: 1, .. }), &TyBool) => write!(f, "true"),
2250 (Value::Scalar(Scalar::Bits { bits, .. }), &TyFloat(ast::FloatTy::F32)) => {
2251 write!(f, "{}f32", Single::from_bits(bits))
2253 (Value::Scalar(Scalar::Bits { bits, .. }), &TyFloat(ast::FloatTy::F64)) => {
2254 write!(f, "{}f64", Double::from_bits(bits))
2256 (Value::Scalar(Scalar::Bits { bits, .. }), &TyUint(ui)) => write!(f, "{:?}{}", bits, ui),
2257 (Value::Scalar(Scalar::Bits { bits, .. }), &TyInt(i)) => {
2258 let bit_width = ty::tls::with(|tcx| {
2259 let ty = tcx.lift_to_global(&ty).unwrap();
2260 tcx.layout_of(ty::ParamEnv::empty().and(ty))
2265 let shift = 128 - bit_width;
2266 write!(f, "{:?}{}", ((bits as i128) << shift) >> shift, i)
2268 (Value::Scalar(Scalar::Bits { bits, .. }), &TyChar) => {
2269 write!(f, "{:?}", ::std::char::from_u32(bits as u32).unwrap())
2271 (_, &TyFnDef(did, _)) => write!(f, "{}", item_path_str(did)),
2273 Value::ScalarPair(Scalar::Ptr(ptr), Scalar::Bits { bits: len, .. }),
2274 &TyRef(_, &ty::TyS { sty: TyStr, .. }, _),
2275 ) => ty::tls::with(|tcx| match tcx.alloc_map.lock().get(ptr.alloc_id) {
2276 Some(interpret::AllocType::Memory(alloc)) => {
2277 assert_eq!(len as usize as u128, len);
2278 let slice = &alloc.bytes[(ptr.offset.bytes() as usize)..][..(len as usize)];
2279 let s = ::std::str::from_utf8(slice).expect("non utf8 str from miri");
2280 write!(f, "{:?}", s)
2282 _ => write!(f, "pointer to erroneous constant {:?}, {:?}", ptr, len),
2284 _ => write!(f, "{:?}:{}", value, ty),
2288 fn item_path_str(def_id: DefId) -> String {
2289 ty::tls::with(|tcx| tcx.item_path_str(def_id))
2292 impl<'tcx> ControlFlowGraph for Mir<'tcx> {
2293 type Node = BasicBlock;
2295 fn num_nodes(&self) -> usize {
2296 self.basic_blocks.len()
2299 fn start_node(&self) -> Self::Node {
2303 fn predecessors<'graph>(
2306 ) -> <Self as GraphPredecessors<'graph>>::Iter {
2307 self.predecessors_for(node).clone().into_iter()
2309 fn successors<'graph>(
2312 ) -> <Self as GraphSuccessors<'graph>>::Iter {
2313 self.basic_blocks[node].terminator().successors().cloned()
2317 impl<'a, 'b> GraphPredecessors<'b> for Mir<'a> {
2318 type Item = BasicBlock;
2319 type Iter = IntoIter<BasicBlock>;
2322 impl<'a, 'b> GraphSuccessors<'b> for Mir<'a> {
2323 type Item = BasicBlock;
2324 type Iter = iter::Cloned<Successors<'b>>;
2327 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
2328 pub struct Location {
2329 /// the location is within this block
2330 pub block: BasicBlock,
2332 /// the location is the start of the statement; or, if `statement_index`
2333 /// == num-statements, then the start of the terminator.
2334 pub statement_index: usize,
2337 impl fmt::Debug for Location {
2338 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
2339 write!(fmt, "{:?}[{}]", self.block, self.statement_index)
2344 pub const START: Location = Location {
2349 /// Returns the location immediately after this one within the enclosing block.
2351 /// Note that if this location represents a terminator, then the
2352 /// resulting location would be out of bounds and invalid.
2353 pub fn successor_within_block(&self) -> Location {
2356 statement_index: self.statement_index + 1,
2360 pub fn dominates(&self, other: Location, dominators: &Dominators<BasicBlock>) -> bool {
2361 if self.block == other.block {
2362 self.statement_index <= other.statement_index
2364 dominators.is_dominated_by(other.block, self.block)
2369 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2370 pub enum UnsafetyViolationKind {
2372 ExternStatic(ast::NodeId),
2373 BorrowPacked(ast::NodeId),
2376 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2377 pub struct UnsafetyViolation {
2378 pub source_info: SourceInfo,
2379 pub description: InternedString,
2380 pub kind: UnsafetyViolationKind,
2383 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2384 pub struct UnsafetyCheckResult {
2385 /// Violations that are propagated *upwards* from this function
2386 pub violations: Lrc<[UnsafetyViolation]>,
2387 /// unsafe blocks in this function, along with whether they are used. This is
2388 /// used for the "unused_unsafe" lint.
2389 pub unsafe_blocks: Lrc<[(ast::NodeId, bool)]>,
2392 /// The layout of generator state
2393 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2394 pub struct GeneratorLayout<'tcx> {
2395 pub fields: Vec<LocalDecl<'tcx>>,
2398 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2399 pub struct BorrowCheckResult<'gcx> {
2400 pub closure_requirements: Option<ClosureRegionRequirements<'gcx>>,
2401 pub used_mut_upvars: SmallVec<[Field; 8]>,
2404 /// After we borrow check a closure, we are left with various
2405 /// requirements that we have inferred between the free regions that
2406 /// appear in the closure's signature or on its field types. These
2407 /// requirements are then verified and proved by the closure's
2408 /// creating function. This struct encodes those requirements.
2410 /// The requirements are listed as being between various
2411 /// `RegionVid`. The 0th region refers to `'static`; subsequent region
2412 /// vids refer to the free regions that appear in the closure (or
2413 /// generator's) type, in order of appearance. (This numbering is
2414 /// actually defined by the `UniversalRegions` struct in the NLL
2415 /// region checker. See for example
2416 /// `UniversalRegions::closure_mapping`.) Note that we treat the free
2417 /// regions in the closure's type "as if" they were erased, so their
2418 /// precise identity is not important, only their position.
2420 /// Example: If type check produces a closure with the closure substs:
2423 /// ClosureSubsts = [
2424 /// i8, // the "closure kind"
2425 /// for<'x> fn(&'a &'x u32) -> &'x u32, // the "closure signature"
2426 /// &'a String, // some upvar
2430 /// here, there is one unique free region (`'a`) but it appears
2431 /// twice. We would "renumber" each occurrence to a unique vid, as follows:
2434 /// ClosureSubsts = [
2435 /// i8, // the "closure kind"
2436 /// for<'x> fn(&'1 &'x u32) -> &'x u32, // the "closure signature"
2437 /// &'2 String, // some upvar
2441 /// Now the code might impose a requirement like `'1: '2`. When an
2442 /// instance of the closure is created, the corresponding free regions
2443 /// can be extracted from its type and constrained to have the given
2444 /// outlives relationship.
2446 /// In some cases, we have to record outlives requirements between
2447 /// types and regions as well. In that case, if those types include
2448 /// any regions, those regions are recorded as `ReClosureBound`
2449 /// instances assigned one of these same indices. Those regions will
2450 /// be substituted away by the creator. We use `ReClosureBound` in
2451 /// that case because the regions must be allocated in the global
2452 /// TyCtxt, and hence we cannot use `ReVar` (which is what we use
2453 /// internally within the rest of the NLL code).
2454 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2455 pub struct ClosureRegionRequirements<'gcx> {
2456 /// The number of external regions defined on the closure. In our
2457 /// example above, it would be 3 -- one for `'static`, then `'1`
2458 /// and `'2`. This is just used for a sanity check later on, to
2459 /// make sure that the number of regions we see at the callsite
2461 pub num_external_vids: usize,
2463 /// Requirements between the various free regions defined in
2465 pub outlives_requirements: Vec<ClosureOutlivesRequirement<'gcx>>,
2468 /// Indicates an outlives constraint between a type or between two
2469 /// free-regions declared on the closure.
2470 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2471 pub struct ClosureOutlivesRequirement<'tcx> {
2472 // This region or type ...
2473 pub subject: ClosureOutlivesSubject<'tcx>,
2475 // .. must outlive this one.
2476 pub outlived_free_region: ty::RegionVid,
2478 // If not, report an error here.
2479 pub blame_span: Span,
2482 /// The subject of a ClosureOutlivesRequirement -- that is, the thing
2483 /// that must outlive some region.
2484 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2485 pub enum ClosureOutlivesSubject<'tcx> {
2486 /// Subject is a type, typically a type parameter, but could also
2487 /// be a projection. Indicates a requirement like `T: 'a` being
2488 /// passed to the caller, where the type here is `T`.
2490 /// The type here is guaranteed not to contain any free regions at
2494 /// Subject is a free region from the closure. Indicates a requirement
2495 /// like `'a: 'b` being passed to the caller; the region here is `'a`.
2496 Region(ty::RegionVid),
2500 * TypeFoldable implementations for MIR types
2503 CloneTypeFoldableAndLiftImpls! {
2510 SourceScopeLocalData,
2513 BraceStructTypeFoldableImpl! {
2514 impl<'tcx> TypeFoldable<'tcx> for Mir<'tcx> {
2517 source_scope_local_data,
2531 BraceStructTypeFoldableImpl! {
2532 impl<'tcx> TypeFoldable<'tcx> for GeneratorLayout<'tcx> {
2537 BraceStructTypeFoldableImpl! {
2538 impl<'tcx> TypeFoldable<'tcx> for LocalDecl<'tcx> {
2549 BraceStructTypeFoldableImpl! {
2550 impl<'tcx> TypeFoldable<'tcx> for BasicBlockData<'tcx> {
2557 BraceStructTypeFoldableImpl! {
2558 impl<'tcx> TypeFoldable<'tcx> for ValidationOperand<'tcx, Place<'tcx>> {
2559 place, ty, re, mutbl
2563 BraceStructTypeFoldableImpl! {
2564 impl<'tcx> TypeFoldable<'tcx> for Statement<'tcx> {
2569 EnumTypeFoldableImpl! {
2570 impl<'tcx> TypeFoldable<'tcx> for StatementKind<'tcx> {
2571 (StatementKind::Assign)(a, b),
2572 (StatementKind::ReadForMatch)(place),
2573 (StatementKind::SetDiscriminant) { place, variant_index },
2574 (StatementKind::StorageLive)(a),
2575 (StatementKind::StorageDead)(a),
2576 (StatementKind::InlineAsm) { asm, outputs, inputs },
2577 (StatementKind::Validate)(a, b),
2578 (StatementKind::EndRegion)(a),
2579 (StatementKind::UserAssertTy)(a, b),
2580 (StatementKind::Nop),
2584 EnumTypeFoldableImpl! {
2585 impl<'tcx, T> TypeFoldable<'tcx> for ClearCrossCrate<T> {
2586 (ClearCrossCrate::Clear),
2587 (ClearCrossCrate::Set)(a),
2588 } where T: TypeFoldable<'tcx>
2591 impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
2592 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2593 use mir::TerminatorKind::*;
2595 let kind = match self.kind {
2596 Goto { target } => Goto { target: target },
2603 discr: discr.fold_with(folder),
2604 switch_ty: switch_ty.fold_with(folder),
2605 values: values.clone(),
2606 targets: targets.clone(),
2613 location: location.fold_with(folder),
2622 } => DropAndReplace {
2623 location: location.fold_with(folder),
2624 value: value.fold_with(folder),
2633 value: value.fold_with(folder),
2643 let dest = destination
2645 .map(|&(ref loc, dest)| (loc.fold_with(folder), dest));
2648 func: func.fold_with(folder),
2649 args: args.fold_with(folder),
2661 let msg = if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
2662 EvalErrorKind::BoundsCheck {
2663 len: len.fold_with(folder),
2664 index: index.fold_with(folder),
2670 cond: cond.fold_with(folder),
2677 GeneratorDrop => GeneratorDrop,
2681 Unreachable => Unreachable,
2684 ref imaginary_targets,
2687 imaginary_targets: imaginary_targets.clone(),
2698 source_info: self.source_info,
2703 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2704 use mir::TerminatorKind::*;
2711 } => discr.visit_with(visitor) || switch_ty.visit_with(visitor),
2712 Drop { ref location, .. } => location.visit_with(visitor),
2717 } => location.visit_with(visitor) || value.visit_with(visitor),
2718 Yield { ref value, .. } => value.visit_with(visitor),
2725 let dest = if let Some((ref loc, _)) = *destination {
2726 loc.visit_with(visitor)
2730 dest || func.visit_with(visitor) || args.visit_with(visitor)
2733 ref cond, ref msg, ..
2735 if cond.visit_with(visitor) {
2736 if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
2737 len.visit_with(visitor) || index.visit_with(visitor)
2752 | FalseUnwind { .. } => false,
2757 impl<'tcx> TypeFoldable<'tcx> for Place<'tcx> {
2758 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2760 &Place::Projection(ref p) => Place::Projection(p.fold_with(folder)),
2765 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2766 if let &Place::Projection(ref p) = self {
2767 p.visit_with(visitor)
2774 impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
2775 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2778 Use(ref op) => Use(op.fold_with(folder)),
2779 Repeat(ref op, len) => Repeat(op.fold_with(folder), len),
2780 Ref(region, bk, ref place) => {
2781 Ref(region.fold_with(folder), bk, place.fold_with(folder))
2783 Len(ref place) => Len(place.fold_with(folder)),
2784 Cast(kind, ref op, ty) => Cast(kind, op.fold_with(folder), ty.fold_with(folder)),
2785 BinaryOp(op, ref rhs, ref lhs) => {
2786 BinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
2788 CheckedBinaryOp(op, ref rhs, ref lhs) => {
2789 CheckedBinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
2791 UnaryOp(op, ref val) => UnaryOp(op, val.fold_with(folder)),
2792 Discriminant(ref place) => Discriminant(place.fold_with(folder)),
2793 NullaryOp(op, ty) => NullaryOp(op, ty.fold_with(folder)),
2794 Aggregate(ref kind, ref fields) => {
2795 let kind = box match **kind {
2796 AggregateKind::Array(ty) => AggregateKind::Array(ty.fold_with(folder)),
2797 AggregateKind::Tuple => AggregateKind::Tuple,
2798 AggregateKind::Adt(def, v, substs, n) => {
2799 AggregateKind::Adt(def, v, substs.fold_with(folder), n)
2801 AggregateKind::Closure(id, substs) => {
2802 AggregateKind::Closure(id, substs.fold_with(folder))
2804 AggregateKind::Generator(id, substs, movablity) => {
2805 AggregateKind::Generator(id, substs.fold_with(folder), movablity)
2808 Aggregate(kind, fields.fold_with(folder))
2813 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2816 Use(ref op) => op.visit_with(visitor),
2817 Repeat(ref op, _) => op.visit_with(visitor),
2818 Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor),
2819 Len(ref place) => place.visit_with(visitor),
2820 Cast(_, ref op, ty) => op.visit_with(visitor) || ty.visit_with(visitor),
2821 BinaryOp(_, ref rhs, ref lhs) | CheckedBinaryOp(_, ref rhs, ref lhs) => {
2822 rhs.visit_with(visitor) || lhs.visit_with(visitor)
2824 UnaryOp(_, ref val) => val.visit_with(visitor),
2825 Discriminant(ref place) => place.visit_with(visitor),
2826 NullaryOp(_, ty) => ty.visit_with(visitor),
2827 Aggregate(ref kind, ref fields) => {
2829 AggregateKind::Array(ty) => ty.visit_with(visitor),
2830 AggregateKind::Tuple => false,
2831 AggregateKind::Adt(_, _, substs, _) => substs.visit_with(visitor),
2832 AggregateKind::Closure(_, substs) => substs.visit_with(visitor),
2833 AggregateKind::Generator(_, substs, _) => substs.visit_with(visitor),
2834 }) || fields.visit_with(visitor)
2840 impl<'tcx> TypeFoldable<'tcx> for Operand<'tcx> {
2841 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2843 Operand::Copy(ref place) => Operand::Copy(place.fold_with(folder)),
2844 Operand::Move(ref place) => Operand::Move(place.fold_with(folder)),
2845 Operand::Constant(ref c) => Operand::Constant(c.fold_with(folder)),
2849 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2851 Operand::Copy(ref place) | Operand::Move(ref place) => place.visit_with(visitor),
2852 Operand::Constant(ref c) => c.visit_with(visitor),
2857 impl<'tcx, B, V, T> TypeFoldable<'tcx> for Projection<'tcx, B, V, T>
2859 B: TypeFoldable<'tcx>,
2860 V: TypeFoldable<'tcx>,
2861 T: TypeFoldable<'tcx>,
2863 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2864 use mir::ProjectionElem::*;
2866 let base = self.base.fold_with(folder);
2867 let elem = match self.elem {
2869 Field(f, ref ty) => Field(f, ty.fold_with(folder)),
2870 Index(ref v) => Index(v.fold_with(folder)),
2871 ref elem => elem.clone(),
2874 Projection { base, elem }
2877 fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool {
2878 use mir::ProjectionElem::*;
2880 self.base.visit_with(visitor) || match self.elem {
2881 Field(_, ref ty) => ty.visit_with(visitor),
2882 Index(ref v) => v.visit_with(visitor),
2888 impl<'tcx> TypeFoldable<'tcx> for Field {
2889 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _: &mut F) -> Self {
2892 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
2897 impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> {
2898 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2900 span: self.span.clone(),
2901 ty: self.ty.fold_with(folder),
2902 literal: self.literal.fold_with(folder),
2905 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2906 self.ty.visit_with(visitor) || self.literal.visit_with(visitor)
2910 impl<'tcx> TypeFoldable<'tcx> for Literal<'tcx> {
2911 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2913 Literal::Value { value } => Literal::Value {
2914 value: value.fold_with(folder),
2916 Literal::Promoted { index } => Literal::Promoted { index },
2919 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
2921 Literal::Value { value } => value.visit_with(visitor),
2922 Literal::Promoted { .. } => false,