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fuchsia / third_party / rust / 5c5c8eb864e56ce905742b8e97df5506bba6aeef / . / src / librustc / mir / mod.rs
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// ignore-tidy-filelength
//! MIR datatypes and passes. See the [rustc guide] for more info.
//!
//! [rustc guide]: https://rust-lang.github.io/rustc-guide/mir/index.html
use crate::hir::def::{CtorKind, Namespace};
use crate::hir::def_id::DefId;
use crate::hir::{self, GeneratorKind};
use crate::mir::interpret::{GlobalAlloc, PanicInfo, Scalar};
use crate::mir::visit::MirVisitable;
use crate::ty::adjustment::PointerCast;
use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
use crate::ty::layout::VariantIdx;
use crate::ty::print::{FmtPrinter, Printer};
use crate::ty::subst::{Subst, SubstsRef};
use crate::ty::{
self, AdtDef, CanonicalUserTypeAnnotations, List, Region, Ty, TyCtxt, UserTypeAnnotationIndex,
};
use polonius_engine::Atom;
use rustc_index::bit_set::BitMatrix;
use rustc_data_structures::fx::FxHashSet;
use rustc_data_structures::graph::dominators::Dominators;
use rustc_data_structures::graph::{self, GraphSuccessors};
use rustc_index::vec::{Idx, IndexVec};
use rustc_data_structures::sync::Lrc;
use rustc_macros::HashStable;
use rustc_serialize::{Encodable, Decodable};
use smallvec::SmallVec;
use std::borrow::Cow;
use std::fmt::{self, Debug, Display, Formatter, Write};
use std::ops::Index;
use std::slice;
use std::{iter, mem, option, u32};
use syntax::ast::Name;
use syntax::symbol::Symbol;
use syntax_pos::{Span, DUMMY_SP};
pub use crate::mir::interpret::AssertMessage;
pub use crate::mir::cache::{BodyCache, ReadOnlyBodyCache};
pub use crate::read_only;
mod cache;
pub mod interpret;
pub mod mono;
pub mod tcx;
pub mod traversal;
pub mod visit;
/// Types for locals
type LocalDecls<'tcx> = IndexVec<Local, LocalDecl<'tcx>>;
pub trait HasLocalDecls<'tcx> {
fn local_decls(&self) -> &LocalDecls<'tcx>;
}
impl<'tcx> HasLocalDecls<'tcx> for LocalDecls<'tcx> {
fn local_decls(&self) -> &LocalDecls<'tcx> {
self
}
}
impl<'tcx> HasLocalDecls<'tcx> for Body<'tcx> {
fn local_decls(&self) -> &LocalDecls<'tcx> {
&self.local_decls
}
}
/// The various "big phases" that MIR goes through.
///
/// Warning: ordering of variants is significant.
#[derive(Copy, Clone, RustcEncodable, RustcDecodable, HashStable,
Debug, PartialEq, Eq, PartialOrd, Ord)]
pub enum MirPhase {
Build = 0,
Const = 1,
Validated = 2,
Optimized = 3,
}
impl MirPhase {
/// Gets the index of the current MirPhase within the set of all `MirPhase`s.
pub fn phase_index(&self) -> usize {
*self as usize
}
}
/// The lowered representation of a single function.
#[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable, TypeFoldable)]
pub struct Body<'tcx> {
/// A list of basic blocks. References to basic block use a newtyped index type `BasicBlock`
/// that indexes into this vector.
basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
/// Records how far through the "desugaring and optimization" process this particular
/// MIR has traversed. This is particularly useful when inlining, since in that context
/// we instantiate the promoted constants and add them to our promoted vector -- but those
/// promoted items have already been optimized, whereas ours have not. This field allows
/// us to see the difference and forego optimization on the inlined promoted items.
pub phase: MirPhase,
/// A list of source scopes; these are referenced by statements
/// and used for debuginfo. Indexed by a `SourceScope`.
pub source_scopes: IndexVec<SourceScope, SourceScopeData>,
/// The yield type of the function, if it is a generator.
pub yield_ty: Option<Ty<'tcx>>,
/// Generator drop glue.
pub generator_drop: Option<Box<BodyCache<'tcx>>>,
/// The layout of a generator. Produced by the state transformation.
pub generator_layout: Option<GeneratorLayout<'tcx>>,
/// If this is a generator then record the type of source expression that caused this generator
/// to be created.
pub generator_kind: Option<GeneratorKind>,
/// Declarations of locals.
///
/// The first local is the return value pointer, followed by `arg_count`
/// locals for the function arguments, followed by any user-declared
/// variables and temporaries.
pub local_decls: LocalDecls<'tcx>,
/// User type annotations.
pub user_type_annotations: CanonicalUserTypeAnnotations<'tcx>,
/// The number of arguments this function takes.
///
/// Starting at local 1, `arg_count` locals will be provided by the caller
/// and can be assumed to be initialized.
///
/// If this MIR was built for a constant, this will be 0.
pub arg_count: usize,
/// Mark an argument local (which must be a tuple) as getting passed as
/// its individual components at the LLVM level.
///
/// This is used for the "rust-call" ABI.
pub spread_arg: Option<Local>,
/// Debug information pertaining to user variables, including captures.
pub var_debug_info: Vec<VarDebugInfo<'tcx>>,
/// Mark this MIR of a const context other than const functions as having converted a `&&` or
/// `||` expression into `&` or `|` respectively. This is problematic because if we ever stop
/// this conversion from happening and use short circuiting, we will cause the following code
/// to change the value of `x`: `let mut x = 42; false && { x = 55; true };`
///
/// List of places where control flow was destroyed. Used for error reporting.
pub control_flow_destroyed: Vec<(Span, String)>,
/// A span representing this MIR, for error reporting.
pub span: Span,
}
impl<'tcx> Body<'tcx> {
pub fn new(
basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
source_scopes: IndexVec<SourceScope, SourceScopeData>,
local_decls: LocalDecls<'tcx>,
user_type_annotations: CanonicalUserTypeAnnotations<'tcx>,
arg_count: usize,
var_debug_info: Vec<VarDebugInfo<'tcx>>,
span: Span,
control_flow_destroyed: Vec<(Span, String)>,
generator_kind : Option<GeneratorKind>,
) -> Self {
// We need `arg_count` locals, and one for the return place.
assert!(
local_decls.len() >= arg_count + 1,
"expected at least {} locals, got {}",
arg_count + 1,
local_decls.len()
);
Body {
phase: MirPhase::Build,
basic_blocks,
source_scopes,
yield_ty: None,
generator_drop: None,
generator_layout: None,
generator_kind,
local_decls,
user_type_annotations,
arg_count,
spread_arg: None,
var_debug_info,
span,
control_flow_destroyed,
}
}
#[inline]
pub fn basic_blocks(&self) -> &IndexVec<BasicBlock, BasicBlockData<'tcx>> {
&self.basic_blocks
}
/// Returns `true` if a cycle exists in the control-flow graph that is reachable from the
/// `START_BLOCK`.
pub fn is_cfg_cyclic(&self) -> bool {
graph::is_cyclic(self)
}
#[inline]
pub fn local_kind(&self, local: Local) -> LocalKind {
let index = local.as_usize();
if index == 0 {
debug_assert!(
self.local_decls[local].mutability == Mutability::Mut,
"return place should be mutable"
);
LocalKind::ReturnPointer
} else if index < self.arg_count + 1 {
LocalKind::Arg
} else if self.local_decls[local].is_user_variable() {
LocalKind::Var
} else {
LocalKind::Temp
}
}
/// Returns an iterator over all temporaries.
#[inline]
pub fn temps_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
(self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
let local = Local::new(index);
if self.local_decls[local].is_user_variable() {
None
} else {
Some(local)
}
})
}
/// Returns an iterator over all user-declared locals.
#[inline]
pub fn vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
(self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
let local = Local::new(index);
self.local_decls[local].is_user_variable().then_some(local)
})
}
/// Returns an iterator over all user-declared mutable locals.
#[inline]
pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
(self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
let local = Local::new(index);
let decl = &self.local_decls[local];
if decl.is_user_variable() && decl.mutability == Mutability::Mut {
Some(local)
} else {
None
}
})
}
/// Returns an iterator over all user-declared mutable arguments and locals.
#[inline]
pub fn mut_vars_and_args_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
(1..self.local_decls.len()).filter_map(move |index| {
let local = Local::new(index);
let decl = &self.local_decls[local];
if (decl.is_user_variable() || index < self.arg_count + 1)
&& decl.mutability == Mutability::Mut
{
Some(local)
} else {
None
}
})
}
/// Returns an iterator over all function arguments.
#[inline]
pub fn args_iter(&self) -> impl Iterator<Item = Local> {
let arg_count = self.arg_count;
(1..=arg_count).map(Local::new)
}
/// Returns an iterator over all user-defined variables and compiler-generated temporaries (all
/// locals that are neither arguments nor the return place).
#[inline]
pub fn vars_and_temps_iter(&self) -> impl Iterator<Item = Local> {
let arg_count = self.arg_count;
let local_count = self.local_decls.len();
(arg_count + 1..local_count).map(Local::new)
}
/// Changes a statement to a nop. This is both faster than deleting instructions and avoids
/// invalidating statement indices in `Location`s.
pub fn make_statement_nop(&mut self, location: Location) {
let block = &mut self.basic_blocks[location.block];
debug_assert!(location.statement_index < block.statements.len());
block.statements[location.statement_index].make_nop()
}
/// Returns the source info associated with `location`.
pub fn source_info(&self, location: Location) -> &SourceInfo {
let block = &self[location.block];
let stmts = &block.statements;
let idx = location.statement_index;
if idx < stmts.len() {
&stmts[idx].source_info
} else {
assert_eq!(idx, stmts.len());
&block.terminator().source_info
}
}
/// Checks if `sub` is a sub scope of `sup`
pub fn is_sub_scope(&self, mut sub: SourceScope, sup: SourceScope) -> bool {
while sub != sup {
match self.source_scopes[sub].parent_scope {
None => return false,
Some(p) => sub = p,
}
}
true
}
/// Returns the return type; it always return first element from `local_decls` array.
pub fn return_ty(&self) -> Ty<'tcx> {
self.local_decls[RETURN_PLACE].ty
}
/// Gets the location of the terminator for the given block.
pub fn terminator_loc(&self, bb: BasicBlock) -> Location {
Location { block: bb, statement_index: self[bb].statements.len() }
}
}
#[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub enum Safety {
Safe,
/// Unsafe because of a PushUnsafeBlock
BuiltinUnsafe,
/// Unsafe because of an unsafe fn
FnUnsafe,
/// Unsafe because of an `unsafe` block
ExplicitUnsafe(hir::HirId),
}
impl<'tcx> Index<BasicBlock> for Body<'tcx> {
type Output = BasicBlockData<'tcx>;
#[inline]
fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
&self.basic_blocks()[index]
}
}
#[derive(Copy, Clone, Debug, HashStable, TypeFoldable)]
pub enum ClearCrossCrate<T> {
Clear,
Set(T),
}
impl<T> ClearCrossCrate<T> {
pub fn as_ref(&'a self) -> ClearCrossCrate<&'a T> {
match self {
ClearCrossCrate::Clear => ClearCrossCrate::Clear,
ClearCrossCrate::Set(v) => ClearCrossCrate::Set(v),
}
}
pub fn assert_crate_local(self) -> T {
match self {
ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"),
ClearCrossCrate::Set(v) => v,
}
}
}
impl<T: Encodable> rustc_serialize::UseSpecializedEncodable for ClearCrossCrate<T> {}
impl<T: Decodable> rustc_serialize::UseSpecializedDecodable for ClearCrossCrate<T> {}
/// Grouped information about the source code origin of a MIR entity.
/// Intended to be inspected by diagnostics and debuginfo.
/// Most passes can work with it as a whole, within a single function.
// The unofficial Cranelift backend, at least as of #65828, needs `SourceInfo` to implement `Eq` and
// `Hash`. Please ping @bjorn3 if removing them.
#[derive(Copy, Clone, Debug, Eq, PartialEq, RustcEncodable, RustcDecodable, Hash, HashStable)]
pub struct SourceInfo {
/// The source span for the AST pertaining to this MIR entity.
pub span: Span,
/// The source scope, keeping track of which bindings can be
/// seen by debuginfo, active lint levels, `unsafe {...}`, etc.
pub scope: SourceScope,
}
///////////////////////////////////////////////////////////////////////////
// Mutability and borrow kinds
#[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
pub enum Mutability {
Mut,
Not,
}
impl From<Mutability> for hir::Mutability {
fn from(m: Mutability) -> Self {
match m {
Mutability::Mut => hir::Mutability::Mutable,
Mutability::Not => hir::Mutability::Immutable,
}
}
}
#[derive(
Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, HashStable,
)]
pub enum BorrowKind {
/// Data must be immutable and is aliasable.
Shared,
/// The immediately borrowed place must be immutable, but projections from
/// it don't need to be. For example, a shallow borrow of `a.b` doesn't
/// conflict with a mutable borrow of `a.b.c`.
///
/// This is used when lowering matches: when matching on a place we want to
/// ensure that place have the same value from the start of the match until
/// an arm is selected. This prevents this code from compiling:
///
/// let mut x = &Some(0);
/// match *x {
/// None => (),
/// Some(_) if { x = &None; false } => (),
/// Some(_) => (),
/// }
///
/// This can't be a shared borrow because mutably borrowing (*x as Some).0
/// should not prevent `if let None = x { ... }`, for example, because the
/// mutating `(*x as Some).0` can't affect the discriminant of `x`.
/// We can also report errors with this kind of borrow differently.
Shallow,
/// Data must be immutable but not aliasable. This kind of borrow
/// cannot currently be expressed by the user and is used only in
/// implicit closure bindings. It is needed when the closure is
/// borrowing or mutating a mutable referent, e.g.:
///
/// let x: &mut isize = ...;
/// let y = || *x += 5;
///
/// If we were to try to translate this closure into a more explicit
/// form, we'd encounter an error with the code as written:
///
/// struct Env { x: & &mut isize }
/// let x: &mut isize = ...;
/// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
/// fn fn_ptr(env: &mut Env) { **env.x += 5; }
///
/// This is then illegal because you cannot mutate an `&mut` found
/// in an aliasable location. To solve, you'd have to translate with
/// an `&mut` borrow:
///
/// struct Env { x: & &mut isize }
/// let x: &mut isize = ...;
/// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
/// fn fn_ptr(env: &mut Env) { **env.x += 5; }
///
/// Now the assignment to `**env.x` is legal, but creating a
/// mutable pointer to `x` is not because `x` is not mutable. We
/// could fix this by declaring `x` as `let mut x`. This is ok in
/// user code, if awkward, but extra weird for closures, since the
/// borrow is hidden.
///
/// So we introduce a "unique imm" borrow -- the referent is
/// immutable, but not aliasable. This solves the problem. For
/// simplicity, we don't give users the way to express this
/// borrow, it's just used when translating closures.
Unique,
/// Data is mutable and not aliasable.
Mut {
/// `true` if this borrow arose from method-call auto-ref
/// (i.e., `adjustment::Adjust::Borrow`).
allow_two_phase_borrow: bool,
},
}
impl BorrowKind {
pub fn allows_two_phase_borrow(&self) -> bool {
match *self {
BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => false,
BorrowKind::Mut { allow_two_phase_borrow } => allow_two_phase_borrow,
}
}
}
///////////////////////////////////////////////////////////////////////////
// Variables and temps
rustc_index::newtype_index! {
pub struct Local {
derive [HashStable]
DEBUG_FORMAT = "_{}",
const RETURN_PLACE = 0,
}
}
impl Atom for Local {
fn index(self) -> usize {
Idx::index(self)
}
}
/// Classifies locals into categories. See `Body::local_kind`.
#[derive(PartialEq, Eq, Debug, HashStable)]
pub enum LocalKind {
/// User-declared variable binding.
Var,
/// Compiler-introduced temporary.
Temp,
/// Function argument.
Arg,
/// Location of function's return value.
ReturnPointer,
}
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub struct VarBindingForm<'tcx> {
/// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`?
pub binding_mode: ty::BindingMode,
/// If an explicit type was provided for this variable binding,
/// this holds the source Span of that type.
///
/// NOTE: if you want to change this to a `HirId`, be wary that
/// doing so breaks incremental compilation (as of this writing),
/// while a `Span` does not cause our tests to fail.
pub opt_ty_info: Option<Span>,
/// Place of the RHS of the =, or the subject of the `match` where this
/// variable is initialized. None in the case of `let PATTERN;`.
/// Some((None, ..)) in the case of and `let [mut] x = ...` because
/// (a) the right-hand side isn't evaluated as a place expression.
/// (b) it gives a way to separate this case from the remaining cases
/// for diagnostics.
pub opt_match_place: Option<(Option<Place<'tcx>>, Span)>,
/// The span of the pattern in which this variable was bound.
pub pat_span: Span,
}
#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
pub enum BindingForm<'tcx> {
/// This is a binding for a non-`self` binding, or a `self` that has an explicit type.
Var(VarBindingForm<'tcx>),
/// Binding for a `self`/`&self`/`&mut self` binding where the type is implicit.
ImplicitSelf(ImplicitSelfKind),
/// Reference used in a guard expression to ensure immutability.
RefForGuard,
}
/// Represents what type of implicit self a function has, if any.
#[derive(Clone, Copy, PartialEq, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub enum ImplicitSelfKind {
/// Represents a `fn x(self);`.
Imm,
/// Represents a `fn x(mut self);`.
Mut,
/// Represents a `fn x(&self);`.
ImmRef,
/// Represents a `fn x(&mut self);`.
MutRef,
/// Represents when a function does not have a self argument or
/// when a function has a `self: X` argument.
None,
}
CloneTypeFoldableAndLiftImpls! { BindingForm<'tcx>, }
mod binding_form_impl {
use crate::ich::StableHashingContext;
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
use super::BindingForm::*;
::std::mem::discriminant(self).hash_stable(hcx, hasher);
match self {
Var(binding) => binding.hash_stable(hcx, hasher),
ImplicitSelf(kind) => kind.hash_stable(hcx, hasher),
RefForGuard => (),
}
}
}
}
/// `BlockTailInfo` is attached to the `LocalDecl` for temporaries
/// created during evaluation of expressions in a block tail
/// expression; that is, a block like `{ STMT_1; STMT_2; EXPR }`.
///
/// It is used to improve diagnostics when such temporaries are
/// involved in borrow_check errors, e.g., explanations of where the
/// temporaries come from, when their destructors are run, and/or how
/// one might revise the code to satisfy the borrow checker's rules.
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub struct BlockTailInfo {
/// If `true`, then the value resulting from evaluating this tail
/// expression is ignored by the block's expression context.
///
/// Examples include `{ ...; tail };` and `let _ = { ...; tail };`
/// but not e.g., `let _x = { ...; tail };`
pub tail_result_is_ignored: bool,
}
/// A MIR local.
///
/// This can be a binding declared by the user, a temporary inserted by the compiler, a function
/// argument, or the return place.
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
pub struct LocalDecl<'tcx> {
/// Whether this is a mutable minding (i.e., `let x` or `let mut x`).
///
/// Temporaries and the return place are always mutable.
pub mutability: Mutability,
// FIXME(matthewjasper) Don't store in this in `Body`
pub local_info: LocalInfo<'tcx>,
/// `true` if this is an internal local.
///
/// These locals are not based on types in the source code and are only used
/// for a few desugarings at the moment.
///
/// The generator transformation will sanity check the locals which are live
/// across a suspension point against the type components of the generator
/// which type checking knows are live across a suspension point. We need to
/// flag drop flags to avoid triggering this check as they are introduced
/// after typeck.
///
/// Unsafety checking will also ignore dereferences of these locals,
/// so they can be used for raw pointers only used in a desugaring.
///
/// This should be sound because the drop flags are fully algebraic, and
/// therefore don't affect the OIBIT or outlives properties of the
/// generator.
pub internal: bool,
/// If this local is a temporary and `is_block_tail` is `Some`,
/// then it is a temporary created for evaluation of some
/// subexpression of some block's tail expression (with no
/// intervening statement context).
// FIXME(matthewjasper) Don't store in this in `Body`
pub is_block_tail: Option<BlockTailInfo>,
/// The type of this local.
pub ty: Ty<'tcx>,
/// If the user manually ascribed a type to this variable,
/// e.g., via `let x: T`, then we carry that type here. The MIR
/// borrow checker needs this information since it can affect
/// region inference.
// FIXME(matthewjasper) Don't store in this in `Body`
pub user_ty: UserTypeProjections,
/// The *syntactic* (i.e., not visibility) source scope the local is defined
/// in. If the local was defined in a let-statement, this
/// is *within* the let-statement, rather than outside
/// of it.
///
/// This is needed because the visibility source scope of locals within
/// a let-statement is weird.
///
/// The reason is that we want the local to be *within* the let-statement
/// for lint purposes, but we want the local to be *after* the let-statement
/// for names-in-scope purposes.
///
/// That's it, if we have a let-statement like the one in this
/// function:
///
/// ```
/// fn foo(x: &str) {
/// #[allow(unused_mut)]
/// let mut x: u32 = { // <- one unused mut
/// let mut y: u32 = x.parse().unwrap();
/// y + 2
/// };
/// drop(x);
/// }
/// ```
///
/// Then, from a lint point of view, the declaration of `x: u32`
/// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the
/// lint scopes are the same as the AST/HIR nesting.
///
/// However, from a name lookup point of view, the scopes look more like
/// as if the let-statements were `match` expressions:
///
/// ```
/// fn foo(x: &str) {
/// match {
/// match x.parse().unwrap() {
/// y => y + 2
/// }
/// } {
/// x => drop(x)
/// };
/// }
/// ```
///
/// We care about the name-lookup scopes for debuginfo - if the
/// debuginfo instruction pointer is at the call to `x.parse()`, we
/// want `x` to refer to `x: &str`, but if it is at the call to
/// `drop(x)`, we want it to refer to `x: u32`.
///
/// To allow both uses to work, we need to have more than a single scope
/// for a local. We have the `source_info.scope` represent the "syntactic"
/// lint scope (with a variable being under its let block) while the
/// `var_debug_info.source_info.scope` represents the "local variable"
/// scope (where the "rest" of a block is under all prior let-statements).
///
/// The end result looks like this:
///
/// ```text
/// ROOT SCOPE
/// │{ argument x: &str }
/// │
/// │ │{ #[allow(unused_mut)] } // This is actually split into 2 scopes
/// │ │ // in practice because I'm lazy.
/// │ │
/// │ │← x.source_info.scope
/// │ │← `x.parse().unwrap()`
/// │ │
/// │ │ │← y.source_info.scope
/// │ │
/// │ │ │{ let y: u32 }
/// │ │ │
/// │ │ │← y.var_debug_info.source_info.scope
/// │ │ │← `y + 2`
/// │
/// │ │{ let x: u32 }
/// │ │← x.var_debug_info.source_info.scope
/// │ │← `drop(x)` // This accesses `x: u32`.
/// ```
pub source_info: SourceInfo,
}
/// Extra information about a local that's used for diagnostics.
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
pub enum LocalInfo<'tcx> {
/// A user-defined local variable or function parameter
///
/// The `BindingForm` is solely used for local diagnostics when generating
/// warnings/errors when compiling the current crate, and therefore it need
/// not be visible across crates.
User(ClearCrossCrate<BindingForm<'tcx>>),
/// A temporary created that references the static with the given `DefId`.
StaticRef { def_id: DefId, is_thread_local: bool },
/// Any other temporary, the return place, or an anonymous function parameter.
Other,
}
impl<'tcx> LocalDecl<'tcx> {
/// Returns `true` only if local is a binding that can itself be
/// made mutable via the addition of the `mut` keyword, namely
/// something like the occurrences of `x` in:
/// - `fn foo(x: Type) { ... }`,
/// - `let x = ...`,
/// - or `match ... { C(x) => ... }`
pub fn can_be_made_mutable(&self) -> bool {
match self.local_info {
LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
binding_mode: ty::BindingMode::BindByValue(_),
opt_ty_info: _,
opt_match_place: _,
pat_span: _,
}))) => true,
LocalInfo::User(
ClearCrossCrate::Set(BindingForm::ImplicitSelf(ImplicitSelfKind::Imm)),
) => true,
_ => false,
}
}
/// Returns `true` if local is definitely not a `ref ident` or
/// `ref mut ident` binding. (Such bindings cannot be made into
/// mutable bindings, but the inverse does not necessarily hold).
pub fn is_nonref_binding(&self) -> bool {
match self.local_info {
LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
binding_mode: ty::BindingMode::BindByValue(_),
opt_ty_info: _,
opt_match_place: _,
pat_span: _,
}))) => true,
LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(_))) => true,
_ => false,
}
}
/// Returns `true` if this variable is a named variable or function
/// parameter declared by the user.
#[inline]
pub fn is_user_variable(&self) -> bool {
match self.local_info {
LocalInfo::User(_) => true,
_ => false,
}
}
/// Returns `true` if this is a reference to a variable bound in a `match`
/// expression that is used to access said variable for the guard of the
/// match arm.
pub fn is_ref_for_guard(&self) -> bool {
match self.local_info {
LocalInfo::User(ClearCrossCrate::Set(BindingForm::RefForGuard)) => true,
_ => false,
}
}
/// Returns `Some` if this is a reference to a static item that is used to
/// access that static
pub fn is_ref_to_static(&self) -> bool {
match self.local_info {
LocalInfo::StaticRef { .. } => true,
_ => false,
}
}
/// Returns `Some` if this is a reference to a static item that is used to
/// access that static
pub fn is_ref_to_thread_local(&self) -> bool {
match self.local_info {
LocalInfo::StaticRef { is_thread_local, .. } => is_thread_local,
_ => false,
}
}
/// Returns `true` is the local is from a compiler desugaring, e.g.,
/// `__next` from a `for` loop.
#[inline]
pub fn from_compiler_desugaring(&self) -> bool {
self.source_info.span.desugaring_kind().is_some()
}
/// Creates a new `LocalDecl` for a temporary.
#[inline]
pub fn new_temp(ty: Ty<'tcx>, span: Span) -> Self {
Self::new_local(ty, Mutability::Mut, false, span)
}
/// Converts `self` into same `LocalDecl` except tagged as immutable.
#[inline]
pub fn immutable(mut self) -> Self {
self.mutability = Mutability::Not;
self
}
/// Converts `self` into same `LocalDecl` except tagged as internal temporary.
#[inline]
pub fn block_tail(mut self, info: BlockTailInfo) -> Self {
assert!(self.is_block_tail.is_none());
self.is_block_tail = Some(info);
self
}
/// Creates a new `LocalDecl` for a internal temporary.
#[inline]
pub fn new_internal(ty: Ty<'tcx>, span: Span) -> Self {
Self::new_local(ty, Mutability::Mut, true, span)
}
#[inline]
fn new_local(ty: Ty<'tcx>, mutability: Mutability, internal: bool, span: Span) -> Self {
LocalDecl {
mutability,
ty,
user_ty: UserTypeProjections::none(),
source_info: SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE },
internal,
local_info: LocalInfo::Other,
is_block_tail: None,
}
}
/// Builds a `LocalDecl` for the return place.
///
/// This must be inserted into the `local_decls` list as the first local.
#[inline]
pub fn new_return_place(return_ty: Ty<'_>, span: Span) -> LocalDecl<'_> {
LocalDecl {
mutability: Mutability::Mut,
ty: return_ty,
user_ty: UserTypeProjections::none(),
source_info: SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE },
internal: false,
is_block_tail: None,
local_info: LocalInfo::Other,
}
}
}
/// Debug information pertaining to a user variable.
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
pub struct VarDebugInfo<'tcx> {
pub name: Name,
/// Source info of the user variable, including the scope
/// within which the variable is visible (to debuginfo)
/// (see `LocalDecl`'s `source_info` field for more details).
pub source_info: SourceInfo,
/// Where the data for this user variable is to be found.
/// NOTE(eddyb) There's an unenforced invariant that this `Place` is
/// based on a `Local`, not a `Static`, and contains no indexing.
pub place: Place<'tcx>,
}
///////////////////////////////////////////////////////////////////////////
// BasicBlock
rustc_index::newtype_index! {
pub struct BasicBlock {
derive [HashStable]
DEBUG_FORMAT = "bb{}",
const START_BLOCK = 0,
}
}
impl BasicBlock {
pub fn start_location(self) -> Location {
Location { block: self, statement_index: 0 }
}
}
///////////////////////////////////////////////////////////////////////////
// BasicBlockData and Terminator
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
pub struct BasicBlockData<'tcx> {
/// List of statements in this block.
pub statements: Vec<Statement<'tcx>>,
/// Terminator for this block.
///
/// N.B., this should generally ONLY be `None` during construction.
/// Therefore, you should generally access it via the
/// `terminator()` or `terminator_mut()` methods. The only
/// exception is that certain passes, such as `simplify_cfg`, swap
/// out the terminator temporarily with `None` while they continue
/// to recurse over the set of basic blocks.
pub terminator: Option<Terminator<'tcx>>,
/// If true, this block lies on an unwind path. This is used
/// during codegen where distinct kinds of basic blocks may be
/// generated (particularly for MSVC cleanup). Unwind blocks must
/// only branch to other unwind blocks.
pub is_cleanup: bool,
}
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub struct Terminator<'tcx> {
pub source_info: SourceInfo,
pub kind: TerminatorKind<'tcx>,
}
#[derive(Clone, RustcEncodable, RustcDecodable, HashStable, PartialEq)]
pub enum TerminatorKind<'tcx> {
/// Block should have one successor in the graph; we jump there.
Goto { target: BasicBlock },
/// Operand evaluates to an integer; jump depending on its value
/// to one of the targets, and otherwise fallback to `otherwise`.
SwitchInt {
/// The discriminant value being tested.
discr: Operand<'tcx>,
/// The type of value being tested.
switch_ty: Ty<'tcx>,
/// Possible values. The locations to branch to in each case
/// are found in the corresponding indices from the `targets` vector.
values: Cow<'tcx, [u128]>,
/// Possible branch sites. The last element of this vector is used
/// for the otherwise branch, so targets.len() == values.len() + 1
/// should hold.
//
// This invariant is quite non-obvious and also could be improved.
// One way to make this invariant is to have something like this instead:
//
// branches: Vec<(ConstInt, BasicBlock)>,
// otherwise: Option<BasicBlock> // exhaustive if None
//
// However we’ve decided to keep this as-is until we figure a case
// where some other approach seems to be strictly better than other.
targets: Vec<BasicBlock>,
},
/// Indicates that the landing pad is finished and unwinding should
/// continue. Emitted by `build::scope::diverge_cleanup`.
Resume,
/// Indicates that the landing pad is finished and that the process
/// should abort. Used to prevent unwinding for foreign items.
Abort,
/// Indicates a normal return. The return place should have
/// been filled in by now. This should occur at most once.
Return,
/// Indicates a terminator that can never be reached.
Unreachable,
/// Drop the `Place`.
Drop { location: Place<'tcx>, target: BasicBlock, unwind: Option<BasicBlock> },
/// Drop the `Place` and assign the new value over it. This ensures
/// that the assignment to `P` occurs *even if* the destructor for
/// place unwinds. Its semantics are best explained by the
/// elaboration:
///
/// ```
/// BB0 {
/// DropAndReplace(P <- V, goto BB1, unwind BB2)
/// }
/// ```
///
/// becomes
///
/// ```
/// BB0 {
/// Drop(P, goto BB1, unwind BB2)
/// }
/// BB1 {
/// // P is now uninitialized
/// P <- V
/// }
/// BB2 {
/// // P is now uninitialized -- its dtor panicked
/// P <- V
/// }
/// ```
DropAndReplace {
location: Place<'tcx>,
value: Operand<'tcx>,
target: BasicBlock,
unwind: Option<BasicBlock>,
},
/// Block ends with a call of a converging function.
Call {
/// The function that’s being called.
func: Operand<'tcx>,
/// Arguments the function is called with.
/// These are owned by the callee, which is free to modify them.
/// This allows the memory occupied by "by-value" arguments to be
/// reused across function calls without duplicating the contents.
args: Vec<Operand<'tcx>>,
/// Destination for the return value. If some, the call is converging.
destination: Option<(Place<'tcx>, BasicBlock)>,
/// Cleanups to be done if the call unwinds.
cleanup: Option<BasicBlock>,
/// `true` if this is from a call in HIR rather than from an overloaded
/// operator. True for overloaded function call.
from_hir_call: bool,
},
/// Jump to the target if the condition has the expected value,
/// otherwise panic with a message and a cleanup target.
Assert {
cond: Operand<'tcx>,
expected: bool,
msg: AssertMessage<'tcx>,
target: BasicBlock,
cleanup: Option<BasicBlock>,
},
/// A suspend point.
Yield {
/// The value to return.
value: Operand<'tcx>,
/// Where to resume to.
resume: BasicBlock,
/// Cleanup to be done if the generator is dropped at this suspend point.
drop: Option<BasicBlock>,
},
/// Indicates the end of the dropping of a generator.
GeneratorDrop,
/// A block where control flow only ever takes one real path, but borrowck
/// needs to be more conservative.
FalseEdges {
/// The target normal control flow will take.
real_target: BasicBlock,
/// A block control flow could conceptually jump to, but won't in
/// practice.
imaginary_target: BasicBlock,
},
/// A terminator for blocks that only take one path in reality, but where we
/// reserve the right to unwind in borrowck, even if it won't happen in practice.
/// This can arise in infinite loops with no function calls for example.
FalseUnwind {
/// The target normal control flow will take.
real_target: BasicBlock,
/// The imaginary cleanup block link. This particular path will never be taken
/// in practice, but in order to avoid fragility we want to always
/// consider it in borrowck. We don't want to accept programs which
/// pass borrowck only when `panic=abort` or some assertions are disabled
/// due to release vs. debug mode builds. This needs to be an `Option` because
/// of the `remove_noop_landing_pads` and `no_landing_pads` passes.
unwind: Option<BasicBlock>,
},
}
pub type Successors<'a> =
iter::Chain<option::IntoIter<&'a BasicBlock>, slice::Iter<'a, BasicBlock>>;
pub type SuccessorsMut<'a> =
iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>;
impl<'tcx> Terminator<'tcx> {
pub fn successors(&self) -> Successors<'_> {
self.kind.successors()
}
pub fn successors_mut(&mut self) -> SuccessorsMut<'_> {
self.kind.successors_mut()
}
pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
self.kind.unwind()
}
pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
self.kind.unwind_mut()
}
}
impl<'tcx> TerminatorKind<'tcx> {
pub fn if_(
tcx: TyCtxt<'tcx>,
cond: Operand<'tcx>,
t: BasicBlock,
f: BasicBlock,
) -> TerminatorKind<'tcx> {
static BOOL_SWITCH_FALSE: &'static [u128] = &[0];
TerminatorKind::SwitchInt {
discr: cond,
switch_ty: tcx.types.bool,
values: From::from(BOOL_SWITCH_FALSE),
targets: vec![f, t],
}
}
pub fn successors(&self) -> Successors<'_> {
use self::TerminatorKind::*;
match *self {
Resume
| Abort
| GeneratorDrop
| Return
| Unreachable
| Call { destination: None, cleanup: None, .. } => None.into_iter().chain(&[]),
Goto { target: ref t }
| Call { destination: None, cleanup: Some(ref t), .. }
| Call { destination: Some((_, ref t)), cleanup: None, .. }
| Yield { resume: ref t, drop: None, .. }
| DropAndReplace { target: ref t, unwind: None, .. }
| Drop { target: ref t, unwind: None, .. }
| Assert { target: ref t, cleanup: None, .. }
| FalseUnwind { real_target: ref t, unwind: None } => Some(t).into_iter().chain(&[]),
Call { destination: Some((_, ref t)), cleanup: Some(ref u), .. }
| Yield { resume: ref t, drop: Some(ref u), .. }
| DropAndReplace { target: ref t, unwind: Some(ref u), .. }
| Drop { target: ref t, unwind: Some(ref u), .. }
| Assert { target: ref t, cleanup: Some(ref u), .. }
| FalseUnwind { real_target: ref t, unwind: Some(ref u) } => {
Some(t).into_iter().chain(slice::from_ref(u))
}
SwitchInt { ref targets, .. } => None.into_iter().chain(&targets[..]),
FalseEdges { ref real_target, ref imaginary_target } => {
Some(real_target).into_iter().chain(slice::from_ref(imaginary_target))
}
}
}
pub fn successors_mut(&mut self) -> SuccessorsMut<'_> {
use self::TerminatorKind::*;
match *self {
Resume
| Abort
| GeneratorDrop
| Return
| Unreachable
| Call { destination: None, cleanup: None, .. } => None.into_iter().chain(&mut []),
Goto { target: ref mut t }
| Call { destination: None, cleanup: Some(ref mut t), .. }
| Call { destination: Some((_, ref mut t)), cleanup: None, .. }
| Yield { resume: ref mut t, drop: None, .. }
| DropAndReplace { target: ref mut t, unwind: None, .. }
| Drop { target: ref mut t, unwind: None, .. }
| Assert { target: ref mut t, cleanup: None, .. }
| FalseUnwind { real_target: ref mut t, unwind: None } => {
Some(t).into_iter().chain(&mut [])
}
Call { destination: Some((_, ref mut t)), cleanup: Some(ref mut u), .. }
| Yield { resume: ref mut t, drop: Some(ref mut u), .. }
| DropAndReplace { target: ref mut t, unwind: Some(ref mut u), .. }
| Drop { target: ref mut t, unwind: Some(ref mut u), .. }
| Assert { target: ref mut t, cleanup: Some(ref mut u), .. }
| FalseUnwind { real_target: ref mut t, unwind: Some(ref mut u) } => {
Some(t).into_iter().chain(slice::from_mut(u))
}
SwitchInt { ref mut targets, .. } => None.into_iter().chain(&mut targets[..]),
FalseEdges { ref mut real_target, ref mut imaginary_target } => {
Some(real_target).into_iter().chain(slice::from_mut(imaginary_target))
}
}
}
pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
match *self {
TerminatorKind::Goto { .. }
| TerminatorKind::Resume
| TerminatorKind::Abort
| TerminatorKind::Return
| TerminatorKind::Unreachable
| TerminatorKind::GeneratorDrop
| TerminatorKind::Yield { .. }
| TerminatorKind::SwitchInt { .. }
| TerminatorKind::FalseEdges { .. } => None,
TerminatorKind::Call { cleanup: ref unwind, .. }
| TerminatorKind::Assert { cleanup: ref unwind, .. }
| TerminatorKind::DropAndReplace { ref unwind, .. }
| TerminatorKind::Drop { ref unwind, .. }
| TerminatorKind::FalseUnwind { ref unwind, .. } => Some(unwind),
}
}
pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
match *self {
TerminatorKind::Goto { .. }
| TerminatorKind::Resume
| TerminatorKind::Abort
| TerminatorKind::Return
| TerminatorKind::Unreachable
| TerminatorKind::GeneratorDrop
| TerminatorKind::Yield { .. }
| TerminatorKind::SwitchInt { .. }
| TerminatorKind::FalseEdges { .. } => None,
TerminatorKind::Call { cleanup: ref mut unwind, .. }
| TerminatorKind::Assert { cleanup: ref mut unwind, .. }
| TerminatorKind::DropAndReplace { ref mut unwind, .. }
| TerminatorKind::Drop { ref mut unwind, .. }
| TerminatorKind::FalseUnwind { ref mut unwind, .. } => Some(unwind),
}
}
}
impl<'tcx> BasicBlockData<'tcx> {
pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
BasicBlockData { statements: vec![], terminator, is_cleanup: false }
}
/// Accessor for terminator.
///
/// Terminator may not be None after construction of the basic block is complete. This accessor
/// provides a convenience way to reach the terminator.
pub fn terminator(&self) -> &Terminator<'tcx> {
self.terminator.as_ref().expect("invalid terminator state")
}
pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
self.terminator.as_mut().expect("invalid terminator state")
}
pub fn retain_statements<F>(&mut self, mut f: F)
where
F: FnMut(&mut Statement<'_>) -> bool,
{
for s in &mut self.statements {
if !f(s) {
s.make_nop();
}
}
}
pub fn expand_statements<F, I>(&mut self, mut f: F)
where
F: FnMut(&mut Statement<'tcx>) -> Option<I>,
I: iter::TrustedLen<Item = Statement<'tcx>>,
{
// Gather all the iterators we'll need to splice in, and their positions.
let mut splices: Vec<(usize, I)> = vec![];
let mut extra_stmts = 0;
for (i, s) in self.statements.iter_mut().enumerate() {
if let Some(mut new_stmts) = f(s) {
if let Some(first) = new_stmts.next() {
// We can already store the first new statement.
*s = first;
// Save the other statements for optimized splicing.
let remaining = new_stmts.size_hint().0;
if remaining > 0 {
splices.push((i + 1 + extra_stmts, new_stmts));
extra_stmts += remaining;
}
} else {
s.make_nop();
}
}
}
// Splice in the new statements, from the end of the block.
// FIXME(eddyb) This could be more efficient with a "gap buffer"
// where a range of elements ("gap") is left uninitialized, with
// splicing adding new elements to the end of that gap and moving
// existing elements from before the gap to the end of the gap.
// For now, this is safe code, emulating a gap but initializing it.
let mut gap = self.statements.len()..self.statements.len() + extra_stmts;
self.statements.resize(
gap.end,
Statement {
source_info: SourceInfo { span: DUMMY_SP, scope: OUTERMOST_SOURCE_SCOPE },
kind: StatementKind::Nop,
},
);
for (splice_start, new_stmts) in splices.into_iter().rev() {
let splice_end = splice_start + new_stmts.size_hint().0;
while gap.end > splice_end {
gap.start -= 1;
gap.end -= 1;
self.statements.swap(gap.start, gap.end);
}
self.statements.splice(splice_start..splice_end, new_stmts);
gap.end = splice_start;
}
}
pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
if index < self.statements.len() {
&self.statements[index]
} else {
&self.terminator
}
}
}
impl<'tcx> Debug for TerminatorKind<'tcx> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
self.fmt_head(fmt)?;
let successor_count = self.successors().count();
let labels = self.fmt_successor_labels();
assert_eq!(successor_count, labels.len());
match successor_count {
0 => Ok(()),
1 => write!(fmt, " -> {:?}", self.successors().nth(0).unwrap()),
_ => {
write!(fmt, " -> [")?;
for (i, target) in self.successors().enumerate() {
if i > 0 {
write!(fmt, ", ")?;
}
write!(fmt, "{}: {:?}", labels[i], target)?;
}
write!(fmt, "]")
}
}
}
}
impl<'tcx> TerminatorKind<'tcx> {
/// Writes the "head" part of the terminator; that is, its name and the data it uses to pick the
/// successor basic block, if any. The only information not included is the list of possible
/// successors, which may be rendered differently between the text and the graphviz format.
pub fn fmt_head<W: Write>(&self, fmt: &mut W) -> fmt::Result {
use self::TerminatorKind::*;
match *self {
Goto { .. } => write!(fmt, "goto"),
SwitchInt { discr: ref place, .. } => write!(fmt, "switchInt({:?})", place),
Return => write!(fmt, "return"),
GeneratorDrop => write!(fmt, "generator_drop"),
Resume => write!(fmt, "resume"),
Abort => write!(fmt, "abort"),
Yield { ref value, .. } => write!(fmt, "_1 = suspend({:?})", value),
Unreachable => write!(fmt, "unreachable"),
Drop { ref location, .. } => write!(fmt, "drop({:?})", location),
DropAndReplace { ref location, ref value, .. } => {
write!(fmt, "replace({:?} <- {:?})", location, value)
}
Call { ref func, ref args, ref destination, .. } => {
if let Some((ref destination, _)) = *destination {
write!(fmt, "{:?} = ", destination)?;
}
write!(fmt, "{:?}(", func)?;
for (index, arg) in args.iter().enumerate() {
if index > 0 {
write!(fmt, ", ")?;
}
write!(fmt, "{:?}", arg)?;
}
write!(fmt, ")")
}
Assert { ref cond, expected, ref msg, .. } => {
write!(fmt, "assert(")?;
if !expected {
write!(fmt, "!")?;
}
write!(fmt, "{:?}, \"{:?}\")", cond, msg)
}
FalseEdges { .. } => write!(fmt, "falseEdges"),
FalseUnwind { .. } => write!(fmt, "falseUnwind"),
}
}
/// Returns the list of labels for the edges to the successor basic blocks.
pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> {
use self::TerminatorKind::*;
match *self {
Return | Resume | Abort | Unreachable | GeneratorDrop => vec![],
Goto { .. } => vec!["".into()],
SwitchInt { ref values, switch_ty, .. } => ty::tls::with(|tcx| {
let param_env = ty::ParamEnv::empty();
let switch_ty = tcx.lift(&switch_ty).unwrap();
let size = tcx.layout_of(param_env.and(switch_ty)).unwrap().size;
values
.iter()
.map(|&u| {
ty::Const::from_scalar(
tcx,
Scalar::from_uint(u, size).into(),
switch_ty,
)
.to_string()
.into()
})
.chain(iter::once("otherwise".into()))
.collect()
}),
Call { destination: Some(_), cleanup: Some(_), .. } => {
vec!["return".into(), "unwind".into()]
}
Call { destination: Some(_), cleanup: None, .. } => vec!["return".into()],
Call { destination: None, cleanup: Some(_), .. } => vec!["unwind".into()],
Call { destination: None, cleanup: None, .. } => vec![],
Yield { drop: Some(_), .. } => vec!["resume".into(), "drop".into()],
Yield { drop: None, .. } => vec!["resume".into()],
DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => {
vec!["return".into()]
}
DropAndReplace { unwind: Some(_), .. } | Drop { unwind: Some(_), .. } => {
vec!["return".into(), "unwind".into()]
}
Assert { cleanup: None, .. } => vec!["".into()],
Assert { .. } => vec!["success".into(), "unwind".into()],
FalseEdges { .. } => vec!["real".into(), "imaginary".into()],
FalseUnwind { unwind: Some(_), .. } => vec!["real".into(), "cleanup".into()],
FalseUnwind { unwind: None, .. } => vec!["real".into()],
}
}
}
///////////////////////////////////////////////////////////////////////////
// Statements
#[derive(Clone, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
pub struct Statement<'tcx> {
pub source_info: SourceInfo,
pub kind: StatementKind<'tcx>,
}
// `Statement` is used a lot. Make sure it doesn't unintentionally get bigger.
#[cfg(target_arch = "x86_64")]
static_assert_size!(Statement<'_>, 32);
impl Statement<'_> {
/// Changes a statement to a nop. This is both faster than deleting instructions and avoids
/// invalidating statement indices in `Location`s.
pub fn make_nop(&mut self) {
self.kind = StatementKind::Nop
}
/// Changes a statement to a nop and returns the original statement.
pub fn replace_nop(&mut self) -> Self {
Statement {
source_info: self.source_info,
kind: mem::replace(&mut self.kind, StatementKind::Nop),
}
}
}
#[derive(Clone, Debug, PartialEq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
pub enum StatementKind<'tcx> {
/// Write the RHS Rvalue to the LHS Place.
Assign(Box<(Place<'tcx>, Rvalue<'tcx>)>),
/// This represents all the reading that a pattern match may do
/// (e.g., inspecting constants and discriminant values), and the
/// kind of pattern it comes from. This is in order to adapt potential
/// error messages to these specific patterns.
///
/// Note that this also is emitted for regular `let` bindings to ensure that locals that are
/// never accessed still get some sanity checks for, e.g., `let x: ! = ..;`
FakeRead(FakeReadCause, Box<Place<'tcx>>),
/// Write the discriminant for a variant to the enum Place.
SetDiscriminant { place: Box<Place<'tcx>>, variant_index: VariantIdx },
/// Start a live range for the storage of the local.
StorageLive(Local),
/// End the current live range for the storage of the local.
StorageDead(Local),
/// Executes a piece of inline Assembly. Stored in a Box to keep the size
/// of `StatementKind` low.
InlineAsm(Box<InlineAsm<'tcx>>),
/// Retag references in the given place, ensuring they got fresh tags. This is
/// part of the Stacked Borrows model. These statements are currently only interpreted
/// by miri and only generated when "-Z mir-emit-retag" is passed.
/// See <https://internals.rust-lang.org/t/stacked-borrows-an-aliasing-model-for-rust/8153/>
/// for more details.
Retag(RetagKind, Box<Place<'tcx>>),
/// Encodes a user's type ascription. These need to be preserved
/// intact so that NLL can respect them. For example:
///
/// let a: T = y;
///
/// The effect of this annotation is to relate the type `T_y` of the place `y`
/// to the user-given type `T`. The effect depends on the specified variance:
///
/// - `Covariant` -- requires that `T_y <: T`
/// - `Contravariant` -- requires that `T_y :> T`
/// - `Invariant` -- requires that `T_y == T`
/// - `Bivariant` -- no effect
AscribeUserType(Box<(Place<'tcx>, UserTypeProjection)>, ty::Variance),
/// No-op. Useful for deleting instructions without affecting statement indices.
Nop,
}
/// Describes what kind of retag is to be performed.
#[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, PartialEq, Eq, HashStable)]
pub enum RetagKind {
/// The initial retag when entering a function.
FnEntry,
/// Retag preparing for a two-phase borrow.
TwoPhase,
/// Retagging raw pointers.
Raw,
/// A "normal" retag.
Default,
}
/// The `FakeReadCause` describes the type of pattern why a FakeRead statement exists.
#[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable, PartialEq)]
pub enum FakeReadCause {
/// Inject a fake read of the borrowed input at the end of each guards
/// code.
///
/// This should ensure that you cannot change the variant for an enum while
/// you are in the midst of matching on it.
ForMatchGuard,
/// `let x: !; match x {}` doesn't generate any read of x so we need to
/// generate a read of x to check that it is initialized and safe.
ForMatchedPlace,
/// A fake read of the RefWithinGuard version of a bind-by-value variable
/// in a match guard to ensure that it's value hasn't change by the time
/// we create the OutsideGuard version.
ForGuardBinding,
/// Officially, the semantics of
///
/// `let pattern = <expr>;`
///
/// is that `<expr>` is evaluated into a temporary and then this temporary is
/// into the pattern.
///
/// However, if we see the simple pattern `let var = <expr>`, we optimize this to
/// evaluate `<expr>` directly into the variable `var`. This is mostly unobservable,
/// but in some cases it can affect the borrow checker, as in #53695.
/// Therefore, we insert a "fake read" here to ensure that we get
/// appropriate errors.
ForLet,
/// If we have an index expression like
///
/// (*x)[1][{ x = y; 4}]
///
/// then the first bounds check is invalidated when we evaluate the second
/// index expression. Thus we create a fake borrow of `x` across the second
/// indexer, which will cause a borrow check error.
ForIndex,
}
#[derive(Clone, Debug, PartialEq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
pub struct InlineAsm<'tcx> {
pub asm: hir::InlineAsmInner,
pub outputs: Box<[Place<'tcx>]>,
pub inputs: Box<[(Span, Operand<'tcx>)]>,
}
impl Debug for Statement<'_> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
use self::StatementKind::*;
match self.kind {
Assign(box(ref place, ref rv)) => write!(fmt, "{:?} = {:?}", place, rv),
FakeRead(ref cause, ref place) => write!(fmt, "FakeRead({:?}, {:?})", cause, place),
Retag(ref kind, ref place) => write!(
fmt,
"Retag({}{:?})",
match kind {
RetagKind::FnEntry => "[fn entry] ",
RetagKind::TwoPhase => "[2phase] ",
RetagKind::Raw => "[raw] ",
RetagKind::Default => "",
},
place,
),
StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place),
StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place),
SetDiscriminant { ref place, variant_index } => {
write!(fmt, "discriminant({:?}) = {:?}", place, variant_index)
}
InlineAsm(ref asm) => {
write!(fmt, "asm!({:?} : {:?} : {:?})", asm.asm, asm.outputs, asm.inputs)
}
AscribeUserType(box(ref place, ref c_ty), ref variance) => {
write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty)
}
Nop => write!(fmt, "nop"),
}
}
}
///////////////////////////////////////////////////////////////////////////
// Places
/// A path to a value; something that can be evaluated without
/// changing or disturbing program state.
#[derive(
Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, HashStable,
)]
pub struct Place<'tcx> {
pub base: PlaceBase<'tcx>,
/// projection out of a place (access a field, deref a pointer, etc)
pub projection: &'tcx List<PlaceElem<'tcx>>,
}
impl<'tcx> rustc_serialize::UseSpecializedDecodable for Place<'tcx> {}
#[derive(
Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, HashStable,
)]
pub enum PlaceBase<'tcx> {
/// local variable
Local(Local),
/// static or static mut variable
Static(Box<Static<'tcx>>),
}
/// We store the normalized type to avoid requiring normalization when reading MIR
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash,
RustcEncodable, RustcDecodable, HashStable)]
pub struct Static<'tcx> {
pub ty: Ty<'tcx>,
pub kind: StaticKind<'tcx>,
/// The `DefId` of the item this static was declared in. For promoted values, usually, this is
/// the same as the `DefId` of the `mir::Body` containing the `Place` this promoted appears in.
/// However, after inlining, that might no longer be the case as inlined `Place`s are copied
/// into the calling frame.
pub def_id: DefId,
}
#[derive(
Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable, RustcEncodable, RustcDecodable,
)]
pub enum StaticKind<'tcx> {
/// Promoted references consist of an id (`Promoted`) and the substs necessary to monomorphize
/// it. Usually, these substs are just the identity substs for the item. However, the inliner
/// will adjust these substs when it inlines a function based on the substs at the callsite.
Promoted(Promoted, SubstsRef<'tcx>),
Static,
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[derive(RustcEncodable, RustcDecodable, HashStable)]
pub enum ProjectionElem<V, T> {
Deref,
Field(Field, T),
Index(V),
/// These indices are generated by slice patterns. Easiest to explain
/// by example:
///
/// ```
/// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
/// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
/// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
/// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
/// ```
ConstantIndex {
/// index or -index (in Python terms), depending on from_end
offset: u32,
/// thing being indexed must be at least this long
min_length: u32,
/// counting backwards from end?
from_end: bool,
},
/// These indices are generated by slice patterns.
///
/// slice[from:-to] in Python terms.
Subslice {
from: u32,
to: u32,
},
/// "Downcast" to a variant of an ADT. Currently, we only introduce
/// this for ADTs with more than one variant. It may be better to
/// just introduce it always, or always for enums.
///
/// The included Symbol is the name of the variant, used for printing MIR.
Downcast(Option<Symbol>, VariantIdx),
}
impl<V, T> ProjectionElem<V, T> {
/// Returns `true` if the target of this projection may refer to a different region of memory
/// than the base.
fn is_indirect(&self) -> bool {
match self {
Self::Deref => true,
| Self::Field(_, _)
| Self::Index(_)
| Self::ConstantIndex { .. }
| Self::Subslice { .. }
| Self::Downcast(_, _)
=> false
}
}
}
/// Alias for projections as they appear in places, where the base is a place
/// and the index is a local.
pub type PlaceElem<'tcx> = ProjectionElem<Local, Ty<'tcx>>;
impl<'tcx> Copy for PlaceElem<'tcx> { }
// At least on 64 bit systems, `PlaceElem` should not be larger than two pointers.
#[cfg(target_arch = "x86_64")]
static_assert_size!(PlaceElem<'_>, 16);
/// Alias for projections as they appear in `UserTypeProjection`, where we
/// need neither the `V` parameter for `Index` nor the `T` for `Field`.
pub type ProjectionKind = ProjectionElem<(), ()>;
rustc_index::newtype_index! {
pub struct Field {
derive [HashStable]
DEBUG_FORMAT = "field[{}]"
}
}
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct PlaceRef<'a, 'tcx> {
pub base: &'a PlaceBase<'tcx>,
pub projection: &'a [PlaceElem<'tcx>],
}
impl<'tcx> Place<'tcx> {
// FIXME change this to a const fn by also making List::empty a const fn.
pub fn return_place() -> Place<'tcx> {
Place {
base: PlaceBase::Local(RETURN_PLACE),
projection: List::empty(),
}
}
/// Returns `true` if this `Place` contains a `Deref` projection.
///
/// If `Place::is_indirect` returns false, the caller knows that the `Place` refers to the
/// same region of memory as its base.
pub fn is_indirect(&self) -> bool {
self.projection.iter().any(|elem| elem.is_indirect())
}
/// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
/// a single deref of a local.
//
// FIXME: can we safely swap the semantics of `fn base_local` below in here instead?
pub fn local_or_deref_local(&self) -> Option<Local> {
match self.as_ref() {
PlaceRef {
base: &PlaceBase::Local(local),
projection: &[],
} |
PlaceRef {
base: &PlaceBase::Local(local),
projection: &[ProjectionElem::Deref],
} => Some(local),
_ => None,
}
}
/// If this place represents a local variable like `_X` with no
/// projections, return `Some(_X)`.
pub fn as_local(&self) -> Option<Local> {
self.as_ref().as_local()
}
pub fn as_ref(&self) -> PlaceRef<'_, 'tcx> {
PlaceRef {
base: &self.base,
projection: &self.projection,
}
}
}
impl From<Local> for Place<'_> {
fn from(local: Local) -> Self {
Place {
base: local.into(),
projection: List::empty(),
}
}
}
impl From<Local> for PlaceBase<'_> {
fn from(local: Local) -> Self {
PlaceBase::Local(local)
}
}
impl<'a, 'tcx> PlaceRef<'a, 'tcx> {
/// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
/// a single deref of a local.
//
// FIXME: can we safely swap the semantics of `fn base_local` below in here instead?
pub fn local_or_deref_local(&self) -> Option<Local> {
match self {
PlaceRef {
base: PlaceBase::Local(local),
projection: [],
} |
PlaceRef {
base: PlaceBase::Local(local),
projection: [ProjectionElem::Deref],
} => Some(*local),
_ => None,
}
}
/// If this place represents a local variable like `_X` with no
/// projections, return `Some(_X)`.
pub fn as_local(&self) -> Option<Local> {
match self {
PlaceRef { base: PlaceBase::Local(l), projection: [] } => Some(*l),
_ => None,
}
}
}
impl Debug for Place<'_> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
for elem in self.projection.iter().rev() {
match elem {
ProjectionElem::Downcast(_, _) | ProjectionElem::Field(_, _) => {
write!(fmt, "(").unwrap();
}
ProjectionElem::Deref => {
write!(fmt, "(*").unwrap();
}
ProjectionElem::Index(_)
| ProjectionElem::ConstantIndex { .. }
| ProjectionElem::Subslice { .. } => {}
}
}
write!(fmt, "{:?}", self.base)?;
for elem in self.projection.iter() {
match elem {
ProjectionElem::Downcast(Some(name), _index) => {
write!(fmt, " as {})", name)?;
}
ProjectionElem::Downcast(None, index) => {
write!(fmt, " as variant#{:?})", index)?;
}
ProjectionElem::Deref => {
write!(fmt, ")")?;
}
ProjectionElem::Field(field, ty) => {
write!(fmt, ".{:?}: {:?})", field.index(), ty)?;
}
ProjectionElem::Index(ref index) => {
write!(fmt, "[{:?}]", index)?;
}
ProjectionElem::ConstantIndex { offset, min_length, from_end: false } => {
write!(fmt, "[{:?} of {:?}]", offset, min_length)?;
}
ProjectionElem::ConstantIndex { offset, min_length, from_end: true } => {
write!(fmt, "[-{:?} of {:?}]", offset, min_length)?;
}
ProjectionElem::Subslice { from, to } if *to == 0 => {
write!(fmt, "[{:?}:]", from)?;
}
ProjectionElem::Subslice { from, to } if *from == 0 => {
write!(fmt, "[:-{:?}]", to)?;
}
ProjectionElem::Subslice { from, to } => {
write!(fmt, "[{:?}:-{:?}]", from, to)?;
}
}
}
Ok(())
}
}
impl Debug for PlaceBase<'_> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
match *self {
PlaceBase::Local(id) => write!(fmt, "{:?}", id),
PlaceBase::Static(box self::Static { ty, kind: StaticKind::Static, def_id }) => {
write!(fmt, "({}: {:?})", ty::tls::with(|tcx| tcx.def_path_str(def_id)), ty)
}
PlaceBase::Static(box self::Static {
ty, kind: StaticKind::Promoted(promoted, _), def_id: _
}) => {
write!(fmt, "({:?}: {:?})", promoted, ty)
}
}
}
}
///////////////////////////////////////////////////////////////////////////
// Scopes
rustc_index::newtype_index! {
pub struct SourceScope {
derive [HashStable]
DEBUG_FORMAT = "scope[{}]",
const OUTERMOST_SOURCE_SCOPE = 0,
}
}
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub struct SourceScopeData {
pub span: Span,
pub parent_scope: Option<SourceScope>,
/// Crate-local information for this source scope, that can't (and
/// needn't) be tracked across crates.
pub local_data: ClearCrossCrate<SourceScopeLocalData>,
}
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub struct SourceScopeLocalData {
/// An `HirId` with lint levels equivalent to this scope's lint levels.
pub lint_root: hir::HirId,
/// The unsafe block that contains this node.
pub safety: Safety,
}
///////////////////////////////////////////////////////////////////////////
// Operands
/// These are values that can appear inside an rvalue. They are intentionally
/// limited to prevent rvalues from being nested in one another.
#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)]
pub enum Operand<'tcx> {
/// Copy: The value must be available for use afterwards.
///
/// This implies that the type of the place must be `Copy`; this is true
/// by construction during build, but also checked by the MIR type checker.
Copy(Place<'tcx>),
/// Move: The value (including old borrows of it) will not be used again.
///
/// Safe for values of all types (modulo future developments towards `?Move`).
/// Correct usage patterns are enforced by the borrow checker for safe code.
/// `Copy` may be converted to `Move` to enable "last-use" optimizations.
Move(Place<'tcx>),
/// Synthesizes a constant value.
Constant(Box<Constant<'tcx>>),
}
impl<'tcx> Debug for Operand<'tcx> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
use self::Operand::*;
match *self {
Constant(ref a) => write!(fmt, "{:?}", a),
Copy(ref place) => write!(fmt, "{:?}", place),
Move(ref place) => write!(fmt, "move {:?}", place),
}
}
}
impl<'tcx> Operand<'tcx> {
/// Convenience helper to make a constant that refers to the fn
/// with given `DefId` and substs. Since this is used to synthesize
/// MIR, assumes `user_ty` is None.
pub fn function_handle(
tcx: TyCtxt<'tcx>,
def_id: DefId,
substs: SubstsRef<'tcx>,
span: Span,
) -> Self {
let ty = tcx.type_of(def_id).subst(tcx, substs);
Operand::Constant(box Constant {
span,
user_ty: None,
literal: ty::Const::zero_sized(tcx, ty),
})
}
pub fn to_copy(&self) -> Self {
match *self {
Operand::Copy(_) | Operand::Constant(_) => self.clone(),
Operand::Move(ref place) => Operand::Copy(place.clone()),
}
}
}
///////////////////////////////////////////////////////////////////////////
/// Rvalues
#[derive(Clone, RustcEncodable, RustcDecodable, HashStable, PartialEq)]
pub enum Rvalue<'tcx> {
/// x (either a move or copy, depending on type of x)
Use(Operand<'tcx>),
/// [x; 32]
Repeat(Operand<'tcx>, u64),
/// &x or &mut x
Ref(Region<'tcx>, BorrowKind, Place<'tcx>),
/// length of a [X] or [X;n] value
Len(Place<'tcx>),
Cast(CastKind, Operand<'tcx>, Ty<'tcx>),
BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
NullaryOp(NullOp, Ty<'tcx>),
UnaryOp(UnOp, Operand<'tcx>),
/// Read the discriminant of an ADT.
///
/// Undefined (i.e., no effort is made to make it defined, but there’s no reason why it cannot
/// be defined to return, say, a 0) if ADT is not an enum.
Discriminant(Place<'tcx>),
/// Creates an aggregate value, like a tuple or struct. This is
/// only needed because we want to distinguish `dest = Foo { x:
/// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case
/// that `Foo` has a destructor. These rvalues can be optimized
/// away after type-checking and before lowering.
Aggregate(Box<AggregateKind<'tcx>>, Vec<Operand<'tcx>>),
}
#[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
pub enum CastKind {
Misc,
Pointer(PointerCast),
}
#[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
pub enum AggregateKind<'tcx> {
/// The type is of the element
Array(Ty<'tcx>),
Tuple,
/// The second field is the variant index. It's equal to 0 for struct
/// and union expressions. The fourth field is
/// active field number and is present only for union expressions
/// -- e.g., for a union expression `SomeUnion { c: .. }`, the
/// active field index would identity the field `c`
Adt(&'tcx AdtDef, VariantIdx, SubstsRef<'tcx>, Option<UserTypeAnnotationIndex>, Option<usize>),
Closure(DefId, SubstsRef<'tcx>),
Generator(DefId, SubstsRef<'tcx>, hir::Movability),
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
pub enum BinOp {
/// The `+` operator (addition)
Add,
/// The `-` operator (subtraction)
Sub,
/// The `*` operator (multiplication)
Mul,
/// The `/` operator (division)
Div,
/// The `%` operator (modulus)
Rem,
/// The `^` operator (bitwise xor)
BitXor,
/// The `&` operator (bitwise and)
BitAnd,
/// The `|` operator (bitwise or)
BitOr,
/// The `<<` operator (shift left)
Shl,
/// The `>>` operator (shift right)
Shr,
/// The `==` operator (equality)
Eq,
/// The `<` operator (less than)
Lt,
/// The `<=` operator (less than or equal to)
Le,
/// The `!=` operator (not equal to)
Ne,
/// The `>=` operator (greater than or equal to)
Ge,
/// The `>` operator (greater than)
Gt,
/// The `ptr.offset` operator
Offset,
}
impl BinOp {
pub fn is_checkable(self) -> bool {
use self::BinOp::*;
match self {
Add | Sub | Mul | Shl | Shr => true,
_ => false,
}
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
pub enum NullOp {
/// Returns the size of a value of that type
SizeOf,
/// Creates a new uninitialized box for a value of that type
Box,
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
pub enum UnOp {
/// The `!` operator for logical inversion
Not,
/// The `-` operator for negation
Neg,
}
impl<'tcx> Debug for Rvalue<'tcx> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
use self::Rvalue::*;
match *self {
Use(ref place) => write!(fmt, "{:?}", place),
Repeat(ref a, ref b) => write!(fmt, "[{:?}; {:?}]", a, b),
Len(ref a) => write!(fmt, "Len({:?})", a),
Cast(ref kind, ref place, ref ty) => {
write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind)
}
BinaryOp(ref op, ref a, ref b) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
CheckedBinaryOp(ref op, ref a, ref b) => {
write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b)
}
UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
Discriminant(ref place) => write!(fmt, "discriminant({:?})", place),
NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
Ref(region, borrow_kind, ref place) => {
let kind_str = match borrow_kind {
BorrowKind::Shared => "",
BorrowKind::Shallow => "shallow ",
BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ",
};
// When printing regions, add trailing space if necessary.
let print_region = ty::tls::with(|tcx| {
tcx.sess.verbose() || tcx.sess.opts.debugging_opts.identify_regions
});
let region = if print_region {
let mut region = region.to_string();
if region.len() > 0 {
region.push(' ');
}
region
} else {
// Do not even print 'static
String::new()
};
write!(fmt, "&{}{}{:?}", region, kind_str, place)
}
Aggregate(ref kind, ref places) => {
fn fmt_tuple(fmt: &mut Formatter<'_>, places: &[Operand<'_>]) -> fmt::Result {
let mut tuple_fmt = fmt.debug_tuple("");
for place in places {
tuple_fmt.field(place);
}
tuple_fmt.finish()
}
match **kind {
AggregateKind::Array(_) => write!(fmt, "{:?}", places),
AggregateKind::Tuple => match places.len() {
0 => write!(fmt, "()"),
1 => write!(fmt, "({:?},)", places[0]),
_ => fmt_tuple(fmt, places),
},
AggregateKind::Adt(adt_def, variant, substs, _user_ty, _) => {
let variant_def = &adt_def.variants[variant];
let f = &mut *fmt;
ty::tls::with(|tcx| {
let substs = tcx.lift(&substs).expect("could not lift for printing");
FmtPrinter::new(tcx, f, Namespace::ValueNS)
.print_def_path(variant_def.def_id, substs)?;
Ok(())
})?;
match variant_def.ctor_kind {
CtorKind::Const => Ok(()),
CtorKind::Fn => fmt_tuple(fmt, places),
CtorKind::Fictive => {
let mut struct_fmt = fmt.debug_struct("");
for (field, place) in variant_def.fields.iter().zip(places) {
struct_fmt.field(&field.ident.as_str(), place);
}
struct_fmt.finish()
}
}
}
AggregateKind::Closure(def_id, substs) => ty::tls::with(|tcx| {
if let Some(hir_id) = tcx.hir().as_local_hir_id(def_id) {
let name = if tcx.sess.opts.debugging_opts.span_free_formats {
let substs = tcx.lift(&substs).unwrap();
format!(
"[closure@{}]",
tcx.def_path_str_with_substs(def_id, substs),
)
} else {
format!("[closure@{:?}]", tcx.hir().span(hir_id))
};
let mut struct_fmt = fmt.debug_struct(&name);
if let Some(upvars) = tcx.upvars(def_id) {
for (&var_id, place) in upvars.keys().zip(places) {
let var_name = tcx.hir().name(var_id);
struct_fmt.field(&var_name.as_str(), place);
}
}
struct_fmt.finish()
} else {
write!(fmt, "[closure]")
}
}),
AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
if let Some(hir_id) = tcx.hir().as_local_hir_id(def_id) {
let name = format!("[generator@{:?}]", tcx.hir().span(hir_id));
let mut struct_fmt = fmt.debug_struct(&name);
if let Some(upvars) = tcx.upvars(def_id) {
for (&var_id, place) in upvars.keys().zip(places) {
let var_name = tcx.hir().name(var_id);
struct_fmt.field(&var_name.as_str(), place);
}
}
struct_fmt.finish()
} else {
write!(fmt, "[generator]")
}
}),
}
}
}
}
}
///////////////////////////////////////////////////////////////////////////
/// Constants
///
/// Two constants are equal if they are the same constant. Note that
/// this does not necessarily mean that they are "==" in Rust -- in
/// particular one must be wary of `NaN`!
#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)]
pub struct Constant<'tcx> {
pub span: Span,
/// Optional user-given type: for something like
/// `collect::<Vec<_>>`, this would be present and would
/// indicate that `Vec<_>` was explicitly specified.
///
/// Needed for NLL to impose user-given type constraints.
pub user_ty: Option<UserTypeAnnotationIndex>,
pub literal: &'tcx ty::Const<'tcx>,
}
impl Constant<'tcx> {
pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option<DefId> {
match self.literal.val.try_to_scalar() {
Some(Scalar::Ptr(ptr)) => match tcx.alloc_map.lock().get(ptr.alloc_id) {
Some(GlobalAlloc::Static(def_id)) => Some(def_id),
Some(_) => None,
None => {
tcx.sess.delay_span_bug(
DUMMY_SP, "MIR cannot contain dangling const pointers",
);
None
},
},
_ => None,
}
}
}
/// A collection of projections into user types.
///
/// They are projections because a binding can occur a part of a
/// parent pattern that has been ascribed a type.
///
/// Its a collection because there can be multiple type ascriptions on
/// the path from the root of the pattern down to the binding itself.
///
/// An example:
///
/// ```rust
/// struct S<'a>((i32, &'a str), String);
/// let S((_, w): (i32, &'static str), _): S = ...;
/// // ------ ^^^^^^^^^^^^^^^^^^^ (1)
/// // --------------------------------- ^ (2)
/// ```
///
/// The highlights labelled `(1)` show the subpattern `(_, w)` being
/// ascribed the type `(i32, &'static str)`.
///
/// The highlights labelled `(2)` show the whole pattern being
/// ascribed the type `S`.
///
/// In this example, when we descend to `w`, we will have built up the
/// following two projected types:
///
/// * base: `S`, projection: `(base.0).1`
/// * base: `(i32, &'static str)`, projection: `base.1`
///
/// The first will lead to the constraint `w: &'1 str` (for some
/// inferred region `'1`). The second will lead to the constraint `w:
/// &'static str`.
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
pub struct UserTypeProjections {
pub(crate) contents: Vec<(UserTypeProjection, Span)>,
}
impl<'tcx> UserTypeProjections {
pub fn none() -> Self {
UserTypeProjections { contents: vec![] }
}
pub fn from_projections(projs: impl Iterator<Item = (UserTypeProjection, Span)>) -> Self {
UserTypeProjections { contents: projs.collect() }
}
pub fn projections_and_spans(&self) -> impl Iterator<Item = &(UserTypeProjection, Span)> {
self.contents.iter()
}
pub fn projections(&self) -> impl Iterator<Item = &UserTypeProjection> {
self.contents.iter().map(|&(ref user_type, _span)| user_type)
}
pub fn push_projection(mut self, user_ty: &UserTypeProjection, span: Span) -> Self {
self.contents.push((user_ty.clone(), span));
self
}
fn map_projections(
mut self,
mut f: impl FnMut(UserTypeProjection) -> UserTypeProjection,
) -> Self {
self.contents = self.contents.drain(..).map(|(proj, span)| (f(proj), span)).collect();
self
}
pub fn index(self) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.index())
}
pub fn subslice(self, from: u32, to: u32) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.subslice(from, to))
}
pub fn deref(self) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.deref())
}
pub fn leaf(self, field: Field) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.leaf(field))
}
pub fn variant(self, adt_def: &'tcx AdtDef, variant_index: VariantIdx, field: Field) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.variant(adt_def, variant_index, field))
}
}
/// Encodes the effect of a user-supplied type annotation on the
/// subcomponents of a pattern. The effect is determined by applying the
/// given list of proejctions to some underlying base type. Often,
/// the projection element list `projs` is empty, in which case this
/// directly encodes a type in `base`. But in the case of complex patterns with
/// subpatterns and bindings, we want to apply only a *part* of the type to a variable,
/// in which case the `projs` vector is used.
///
/// Examples:
///
/// * `let x: T = ...` -- here, the `projs` vector is empty.
///
/// * `let (x, _): T = ...` -- here, the `projs` vector would contain
/// `field[0]` (aka `.0`), indicating that the type of `s` is
/// determined by finding the type of the `.0` field from `T`.
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, PartialEq)]
pub struct UserTypeProjection {
pub base: UserTypeAnnotationIndex,
pub projs: Vec<ProjectionKind>,
}
impl Copy for ProjectionKind {}
impl UserTypeProjection {
pub(crate) fn index(mut self) -> Self {
self.projs.push(ProjectionElem::Index(()));
self
}
pub(crate) fn subslice(mut self, from: u32, to: u32) -> Self {
self.projs.push(ProjectionElem::Subslice { from, to });
self
}
pub(crate) fn deref(mut self) -> Self {
self.projs.push(ProjectionElem::Deref);
self
}
pub(crate) fn leaf(mut self, field: Field) -> Self {
self.projs.push(ProjectionElem::Field(field, ()));
self
}
pub(crate) fn variant(
mut self,
adt_def: &'tcx AdtDef,
variant_index: VariantIdx,
field: Field,
) -> Self {
self.projs.push(ProjectionElem::Downcast(
Some(adt_def.variants[variant_index].ident.name),
variant_index,
));
self.projs.push(ProjectionElem::Field(field, ()));
self
}
}
CloneTypeFoldableAndLiftImpls! { ProjectionKind, }
impl<'tcx> TypeFoldable<'tcx> for UserTypeProjection {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
use crate::mir::ProjectionElem::*;
let base = self.base.fold_with(folder);
let projs: Vec<_> = self
.projs
.iter()
.map(|elem| match elem {
Deref => Deref,
Field(f, ()) => Field(f.clone(), ()),
Index(()) => Index(()),
elem => elem.clone(),
})
.collect();
UserTypeProjection { base, projs }
}
fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool {
self.base.visit_with(visitor)
// Note: there's nothing in `self.proj` to visit.
}
}
rustc_index::newtype_index! {
pub struct Promoted {
derive [HashStable]
DEBUG_FORMAT = "promoted[{}]"
}
}
impl<'tcx> Debug for Constant<'tcx> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
write!(fmt, "{}", self)
}
}
impl<'tcx> Display for Constant<'tcx> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
write!(fmt, "const ")?;
// FIXME make the default pretty printing of raw pointers more detailed. Here we output the
// debug representation of raw pointers, so that the raw pointers in the mir dump output are
// detailed and just not '{pointer}'.
if let ty::RawPtr(_) = self.literal.ty.kind {
write!(fmt, "{:?} : {}", self.literal.val, self.literal.ty)
} else {
write!(fmt, "{}", self.literal)
}
}
}
impl<'tcx> graph::DirectedGraph for Body<'tcx> {
type Node = BasicBlock;
}
impl<'tcx> graph::WithNumNodes for Body<'tcx> {
fn num_nodes(&self) -> usize {
self.basic_blocks.len()
}
}
impl<'tcx> graph::WithStartNode for Body<'tcx> {
fn start_node(&self) -> Self::Node {
START_BLOCK
}
}
impl<'tcx> graph::WithSuccessors for Body<'tcx> {
fn successors(
&self,
node: Self::Node,
) -> <Self as GraphSuccessors<'_>>::Iter {
self.basic_blocks[node].terminator().successors().cloned()
}
}
impl<'a, 'b> graph::GraphSuccessors<'b> for Body<'a> {
type Item = BasicBlock;
type Iter = iter::Cloned<Successors<'b>>;
}
#[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd, HashStable)]
pub struct Location {
/// The block that the location is within.
pub block: BasicBlock,
/// The location is the position of the start of the statement; or, if
/// `statement_index` equals the number of statements, then the start of the
/// terminator.
pub statement_index: usize,
}
impl fmt::Debug for Location {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(fmt, "{:?}[{}]", self.block, self.statement_index)
}
}
impl Location {
pub const START: Location = Location { block: START_BLOCK, statement_index: 0 };
/// Returns the location immediately after this one within the enclosing block.
///
/// Note that if this location represents a terminator, then the
/// resulting location would be out of bounds and invalid.
pub fn successor_within_block(&self) -> Location {
Location { block: self.block, statement_index: self.statement_index + 1 }
}
/// Returns `true` if `other` is earlier in the control flow graph than `self`.
pub fn is_predecessor_of<'tcx>(
&self,
other: Location,
body: ReadOnlyBodyCache<'_, 'tcx>
) -> bool {
// If we are in the same block as the other location and are an earlier statement
// then we are a predecessor of `other`.
if self.block == other.block && self.statement_index < other.statement_index {
return true;
}
// If we're in another block, then we want to check that block is a predecessor of `other`.
let mut queue: Vec<BasicBlock> = body.predecessors_for(other.block).to_vec();
let mut visited = FxHashSet::default();
while let Some(block) = queue.pop() {
// If we haven't visited this block before, then make sure we visit it's predecessors.
if visited.insert(block) {
queue.extend(body.predecessors_for(block).iter().cloned());
} else {
continue;
}
// If we found the block that `self` is in, then we are a predecessor of `other` (since
// we found that block by looking at the predecessors of `other`).
if self.block == block {
return true;
}
}
false
}
pub fn dominates(&self, other: Location, dominators: &Dominators<BasicBlock>) -> bool {
if self.block == other.block {
self.statement_index <= other.statement_index
} else {
dominators.is_dominated_by(other.block, self.block)
}
}
}
#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)]
pub enum UnsafetyViolationKind {
General,
/// Permitted both in `const fn`s and regular `fn`s.
GeneralAndConstFn,
BorrowPacked(hir::HirId),
}
#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)]
pub struct UnsafetyViolation {
pub source_info: SourceInfo,
pub description: Symbol,
pub details: Symbol,
pub kind: UnsafetyViolationKind,
}
#[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]
pub struct UnsafetyCheckResult {
/// Violations that are propagated *upwards* from this function.
pub violations: Lrc<[UnsafetyViolation]>,
/// `unsafe` blocks in this function, along with whether they are used. This is
/// used for the "unused_unsafe" lint.
pub unsafe_blocks: Lrc<[(hir::HirId, bool)]>,
}
rustc_index::newtype_index! {
pub struct GeneratorSavedLocal {
derive [HashStable]
DEBUG_FORMAT = "_{}",
}
}
/// The layout of generator state.
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
pub struct GeneratorLayout<'tcx> {
/// The type of every local stored inside the generator.
pub field_tys: IndexVec<GeneratorSavedLocal, Ty<'tcx>>,
/// Which of the above fields are in each variant. Note that one field may
/// be stored in multiple variants.
pub variant_fields: IndexVec<VariantIdx, IndexVec<Field, GeneratorSavedLocal>>,
/// Which saved locals are storage-live at the same time. Locals that do not
/// have conflicts with each other are allowed to overlap in the computed
/// layout.
pub storage_conflicts: BitMatrix<GeneratorSavedLocal, GeneratorSavedLocal>,
}
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub struct BorrowCheckResult<'tcx> {
pub closure_requirements: Option<ClosureRegionRequirements<'tcx>>,
pub used_mut_upvars: SmallVec<[Field; 8]>,
}
/// The result of the `mir_const_qualif` query.
///
/// Each field corresponds to an implementer of the `Qualif` trait in
/// `librustc_mir/transform/check_consts/qualifs.rs`. See that file for more information on each
/// `Qualif`.
#[derive(Clone, Copy, Debug, Default, RustcEncodable, RustcDecodable, HashStable)]
pub struct ConstQualifs {
pub has_mut_interior: bool,
pub needs_drop: bool,
}
/// After we borrow check a closure, we are left with various
/// requirements that we have inferred between the free regions that
/// appear in the closure's signature or on its field types. These
/// requirements are then verified and proved by the closure's
/// creating function. This struct encodes those requirements.
///
/// The requirements are listed as being between various
/// `RegionVid`. The 0th region refers to `'static`; subsequent region
/// vids refer to the free regions that appear in the closure (or
/// generator's) type, in order of appearance. (This numbering is
/// actually defined by the `UniversalRegions` struct in the NLL
/// region checker. See for example
/// `UniversalRegions::closure_mapping`.) Note that we treat the free
/// regions in the closure's type "as if" they were erased, so their
/// precise identity is not important, only their position.
///
/// Example: If type check produces a closure with the closure substs:
///
/// ```text
/// ClosureSubsts = [
/// i8, // the "closure kind"
/// for<'x> fn(&'a &'x u32) -> &'x u32, // the "closure signature"
/// &'a String, // some upvar
/// ]
/// ```
///
/// here, there is one unique free region (`'a`) but it appears
/// twice. We would "renumber" each occurrence to a unique vid, as follows:
///
/// ```text
/// ClosureSubsts = [
/// i8, // the "closure kind"
/// for<'x> fn(&'1 &'x u32) -> &'x u32, // the "closure signature"
/// &'2 String, // some upvar
/// ]
/// ```
///
/// Now the code might impose a requirement like `'1: '2`. When an
/// instance of the closure is created, the corresponding free regions
/// can be extracted from its type and constrained to have the given
/// outlives relationship.
///
/// In some cases, we have to record outlives requirements between
/// types and regions as well. In that case, if those types include
/// any regions, those regions are recorded as `ReClosureBound`
/// instances assigned one of these same indices. Those regions will
/// be substituted away by the creator. We use `ReClosureBound` in
/// that case because the regions must be allocated in the global
/// `TyCtxt`, and hence we cannot use `ReVar` (which is what we use
/// internally within the rest of the NLL code).
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub struct ClosureRegionRequirements<'tcx> {
/// The number of external regions defined on the closure. In our
/// example above, it would be 3 -- one for `'static`, then `'1`
/// and `'2`. This is just used for a sanity check later on, to
/// make sure that the number of regions we see at the callsite
/// matches.
pub num_external_vids: usize,
/// Requirements between the various free regions defined in
/// indices.
pub outlives_requirements: Vec<ClosureOutlivesRequirement<'tcx>>,
}
/// Indicates an outlives-constraint between a type or between two
/// free regions declared on the closure.
#[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub struct ClosureOutlivesRequirement<'tcx> {
// This region or type ...
pub subject: ClosureOutlivesSubject<'tcx>,
// ... must outlive this one.
pub outlived_free_region: ty::RegionVid,
// If not, report an error here ...
pub blame_span: Span,
// ... due to this reason.
pub category: ConstraintCategory,
}
/// Outlives-constraints can be categorized to determine whether and why they
/// are interesting (for error reporting). Order of variants indicates sort
/// order of the category, thereby influencing diagnostic output.
///
/// See also [rustc_mir::borrow_check::nll::constraints].
#[derive(
Copy,
Clone,
Debug,
Eq,
PartialEq,
PartialOrd,
Ord,
Hash,
RustcEncodable,
RustcDecodable,
HashStable,
)]
pub enum ConstraintCategory {
Return,
Yield,
UseAsConst,
UseAsStatic,
TypeAnnotation,
Cast,
/// A constraint that came from checking the body of a closure.
///
/// We try to get the category that the closure used when reporting this.
ClosureBounds,
CallArgument,
CopyBound,
SizedBound,
Assignment,
OpaqueType,
/// A "boring" constraint (caused by the given location) is one that
/// the user probably doesn't want to see described in diagnostics,
/// because it is kind of an artifact of the type system setup.
/// Example: `x = Foo { field: y }` technically creates
/// intermediate regions representing the "type of `Foo { field: y
/// }`", and data flows from `y` into those variables, but they
/// are not very interesting. The assignment into `x` on the other
/// hand might be.
Boring,
// Boring and applicable everywhere.
BoringNoLocation,
/// A constraint that doesn't correspond to anything the user sees.
Internal,
}
/// The subject of a `ClosureOutlivesRequirement` -- that is, the thing
/// that must outlive some region.
#[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub enum ClosureOutlivesSubject<'tcx> {
/// Subject is a type, typically a type parameter, but could also
/// be a projection. Indicates a requirement like `T: 'a` being
/// passed to the caller, where the type here is `T`.
///
/// The type here is guaranteed not to contain any free regions at
/// present.
Ty(Ty<'tcx>),
/// Subject is a free region from the closure. Indicates a requirement
/// like `'a: 'b` being passed to the caller; the region here is `'a`.
Region(ty::RegionVid),
}
/*
* `TypeFoldable` implementations for MIR types
*/
CloneTypeFoldableAndLiftImpls! {
BlockTailInfo,
MirPhase,
Mutability,
SourceInfo,
FakeReadCause,
RetagKind,
SourceScope,
SourceScopeData,
SourceScopeLocalData,
UserTypeAnnotationIndex,
}
impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
use crate::mir::TerminatorKind::*;
let kind = match self.kind {
Goto { target } => Goto { target },
SwitchInt { ref discr, switch_ty, ref values, ref targets } => SwitchInt {
discr: discr.fold_with(folder),
switch_ty: switch_ty.fold_with(folder),
values: values.clone(),
targets: targets.clone(),
},
Drop { ref location, target, unwind } => {
Drop { location: location.fold_with(folder), target, unwind }
}
DropAndReplace { ref location, ref value, target, unwind } => DropAndReplace {
location: location.fold_with(folder),
value: value.fold_with(folder),
target,
unwind,
},
Yield { ref value, resume, drop } => {
Yield { value: value.fold_with(folder), resume: resume, drop: drop }
}
Call { ref func, ref args, ref destination, cleanup, from_hir_call } => {
let dest =
destination.as_ref().map(|&(ref loc, dest)| (loc.fold_with(folder), dest));
Call {
func: func.fold_with(folder),
args: args.fold_with(folder),
destination: dest,
cleanup,
from_hir_call,
}
}
Assert { ref cond, expected, ref msg, target, cleanup } => {
use PanicInfo::*;
let msg = match msg {
BoundsCheck { ref len, ref index } =>
BoundsCheck {
len: len.fold_with(folder),
index: index.fold_with(folder),
},
Panic { .. } | Overflow(_) | OverflowNeg | DivisionByZero | RemainderByZero |
ResumedAfterReturn(_) | ResumedAfterPanic(_) =>
msg.clone(),
};
Assert { cond: cond.fold_with(folder), expected, msg, target, cleanup }
}
GeneratorDrop => GeneratorDrop,
Resume => Resume,
Abort => Abort,
Return => Return,
Unreachable => Unreachable,
FalseEdges { real_target, imaginary_target } => {
FalseEdges { real_target, imaginary_target }
}
FalseUnwind { real_target, unwind } => FalseUnwind { real_target, unwind },
};
Terminator { source_info: self.source_info, kind }
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
use crate::mir::TerminatorKind::*;
match self.kind {
SwitchInt { ref discr, switch_ty, .. } => {
discr.visit_with(visitor) || switch_ty.visit_with(visitor)
}
Drop { ref location, .. } => location.visit_with(visitor),
DropAndReplace { ref location, ref value, .. } => {
location.visit_with(visitor) || value.visit_with(visitor)
}
Yield { ref value, .. } => value.visit_with(visitor),
Call { ref func, ref args, ref destination, .. } => {
let dest = if let Some((ref loc, _)) = *destination {
loc.visit_with(visitor)
} else {
false
};
dest || func.visit_with(visitor) || args.visit_with(visitor)
}
Assert { ref cond, ref msg, .. } => {
if cond.visit_with(visitor) {
use PanicInfo::*;
match msg {
BoundsCheck { ref len, ref index } =>
len.visit_with(visitor) || index.visit_with(visitor),
Panic { .. } | Overflow(_) | OverflowNeg |
DivisionByZero | RemainderByZero |
ResumedAfterReturn(_) | ResumedAfterPanic(_) =>
false
}
} else {
false
}
}
Goto { .. }
| Resume
| Abort
| Return
| GeneratorDrop
| Unreachable
| FalseEdges { .. }
| FalseUnwind { .. } => false,
}
}
}
impl<'tcx> TypeFoldable<'tcx> for GeneratorKind {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, _: &mut F) -> Self {
*self
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
false
}
}
impl<'tcx> TypeFoldable<'tcx> for Place<'tcx> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
Place {
base: self.base.fold_with(folder),
projection: self.projection.fold_with(folder),
}
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
self.base.visit_with(visitor) || self.projection.visit_with(visitor)
}
}
impl<'tcx> TypeFoldable<'tcx> for PlaceBase<'tcx> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
match self {
PlaceBase::Local(local) => PlaceBase::Local(local.fold_with(folder)),
PlaceBase::Static(static_) => PlaceBase::Static(static_.fold_with(folder)),
}
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
match self {
PlaceBase::Local(local) => local.visit_with(visitor),
PlaceBase::Static(static_) => (**static_).visit_with(visitor),
}
}
}
impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<PlaceElem<'tcx>> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
let v = self.iter().map(|t| t.fold_with(folder)).collect::<Vec<_>>();
folder.tcx().intern_place_elems(&v)
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
self.iter().any(|t| t.visit_with(visitor))
}
}
impl<'tcx> TypeFoldable<'tcx> for Static<'tcx> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
Static {
ty: self.ty.fold_with(folder),
kind: self.kind.fold_with(folder),
def_id: self.def_id,
}
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
let Static { ty, kind, def_id: _ } = self;
ty.visit_with(visitor) || kind.visit_with(visitor)
}
}
impl<'tcx> TypeFoldable<'tcx> for StaticKind<'tcx> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
match self {
StaticKind::Promoted(promoted, substs) =>
StaticKind::Promoted(promoted.fold_with(folder), substs.fold_with(folder)),
StaticKind::Static => StaticKind::Static
}
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
match self {
StaticKind::Promoted(promoted, substs) =>
promoted.visit_with(visitor) || substs.visit_with(visitor),
StaticKind::Static => { false }
}
}
}
impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
use crate::mir::Rvalue::*;
match *self {
Use(ref op) => Use(op.fold_with(folder)),
Repeat(ref op, len) => Repeat(op.fold_with(folder), len),
Ref(region, bk, ref place) => {
Ref(region.fold_with(folder), bk, place.fold_with(folder))
}
Len(ref place) => Len(place.fold_with(folder)),
Cast(kind, ref op, ty) => Cast(kind, op.fold_with(folder), ty.fold_with(folder)),
BinaryOp(op, ref rhs, ref lhs) => {
BinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
}
CheckedBinaryOp(op, ref rhs, ref lhs) => {
CheckedBinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
}
UnaryOp(op, ref val) => UnaryOp(op, val.fold_with(folder)),
Discriminant(ref place) => Discriminant(place.fold_with(folder)),
NullaryOp(op, ty) => NullaryOp(op, ty.fold_with(folder)),
Aggregate(ref kind, ref fields) => {
let kind = box match **kind {
AggregateKind::Array(ty) => AggregateKind::Array(ty.fold_with(folder)),
AggregateKind::Tuple => AggregateKind::Tuple,
AggregateKind::Adt(def, v, substs, user_ty, n) => AggregateKind::Adt(
def,
v,
substs.fold_with(folder),
user_ty.fold_with(folder),
n,
),
AggregateKind::Closure(id, substs) => {
AggregateKind::Closure(id, substs.fold_with(folder))
}
AggregateKind::Generator(id, substs, movablity) => {
AggregateKind::Generator(id, substs.fold_with(folder), movablity)
}
};
Aggregate(kind, fields.fold_with(folder))
}
}
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
use crate::mir::Rvalue::*;
match *self {
Use(ref op) => op.visit_with(visitor),
Repeat(ref op, _) => op.visit_with(visitor),
Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor),
Len(ref place) => place.visit_with(visitor),
Cast(_, ref op, ty) => op.visit_with(visitor) || ty.visit_with(visitor),
BinaryOp(_, ref rhs, ref lhs) | CheckedBinaryOp(_, ref rhs, ref lhs) => {
rhs.visit_with(visitor) || lhs.visit_with(visitor)
}
UnaryOp(_, ref val) => val.visit_with(visitor),
Discriminant(ref place) => place.visit_with(visitor),
NullaryOp(_, ty) => ty.visit_with(visitor),
Aggregate(ref kind, ref fields) => {
(match **kind {
AggregateKind::Array(ty) => ty.visit_with(visitor),
AggregateKind::Tuple => false,
AggregateKind::Adt(_, _, substs, user_ty, _) => {
substs.visit_with(visitor) || user_ty.visit_with(visitor)
}
AggregateKind::Closure(_, substs) => substs.visit_with(visitor),
AggregateKind::Generator(_, substs, _) => substs.visit_with(visitor),
}) || fields.visit_with(visitor)
}
}
}
}
impl<'tcx> TypeFoldable<'tcx> for Operand<'tcx> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
match *self {
Operand::Copy(ref place) => Operand::Copy(place.fold_with(folder)),
Operand::Move(ref place) => Operand::Move(place.fold_with(folder)),
Operand::Constant(ref c) => Operand::Constant(c.fold_with(folder)),
}
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
match *self {
Operand::Copy(ref place) | Operand::Move(ref place) => place.visit_with(visitor),
Operand::Constant(ref c) => c.visit_with(visitor),
}
}
}
impl<'tcx> TypeFoldable<'tcx> for PlaceElem<'tcx> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
use crate::mir::ProjectionElem::*;
match self {
Deref => Deref,
Field(f, ty) => Field(*f, ty.fold_with(folder)),
Index(v) => Index(v.fold_with(folder)),
elem => elem.clone(),
}
}
fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool {
use crate::mir::ProjectionElem::*;
match self {
Field(_, ty) => ty.visit_with(visitor),
Index(v) => v.visit_with(visitor),
_ => false,
}
}
}
impl<'tcx> TypeFoldable<'tcx> for Field {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, _: &mut F) -> Self {
*self
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
false
}
}
impl<'tcx> TypeFoldable<'tcx> for GeneratorSavedLocal {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, _: &mut F) -> Self {
*self
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
false
}
}
impl<'tcx, R: Idx, C: Idx> TypeFoldable<'tcx> for BitMatrix<R, C> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, _: &mut F) -> Self {
self.clone()
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
false
}
}
impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> {
fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
Constant {
span: self.span.clone(),
user_ty: self.user_ty.fold_with(folder),
literal: self.literal.fold_with(folder),
}
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
self.literal.visit_with(visitor)
}
}