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fuchsia / third_party / rust / a6f4ae864eb9a99117f7475325bf9ffb2c8e8b90 / . / src / librustc / mir / mod.rs
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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! MIR datatypes and passes. See the [rustc guide] for more info.
//!
//! [rustc guide]: https://rust-lang-nursery.github.io/rustc-guide/mir/index.html
use graphviz::IntoCow;
use hir::def::CtorKind;
use hir::def_id::DefId;
use hir::{self, HirId, InlineAsm};
use middle::region;
use mir::interpret::{EvalErrorKind, Scalar, Value, ScalarMaybeUndef};
use mir::visit::MirVisitable;
use rustc_apfloat::ieee::{Double, Single};
use rustc_apfloat::Float;
use rustc_data_structures::graph::dominators::{dominators, Dominators};
use rustc_data_structures::graph::{self, GraphPredecessors, GraphSuccessors};
use rustc_data_structures::indexed_vec::{Idx, IndexVec};
use rustc_data_structures::small_vec::SmallVec;
use rustc_data_structures::sync::Lrc;
use rustc_data_structures::sync::ReadGuard;
use rustc_serialize as serialize;
use std::borrow::Cow;
use std::fmt::{self, Debug, Formatter, Write};
use std::ops::{Index, IndexMut};
use std::slice;
use std::vec::IntoIter;
use std::{iter, mem, option, u32};
use syntax::ast::{self, Name};
use syntax::symbol::InternedString;
use syntax_pos::{Span, DUMMY_SP};
use ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
use ty::subst::{Subst, Substs};
use ty::{self, AdtDef, CanonicalTy, ClosureSubsts, GeneratorSubsts, Region, Ty, TyCtxt};
use util::ppaux;
pub use mir::interpret::AssertMessage;
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 Mir<'tcx> {
fn local_decls(&self) -> &LocalDecls<'tcx> {
&self.local_decls
}
}
/// Lowered representation of a single function.
#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
pub struct Mir<'tcx> {
/// 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>>,
/// List of source scopes; these are referenced by statements
/// and used for debuginfo. Indexed by a `SourceScope`.
pub source_scopes: IndexVec<SourceScope, SourceScopeData>,
/// Crate-local information for each source scope, that can't (and
/// needn't) be tracked across crates.
pub source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
/// Rvalues promoted from this function, such as borrows of constants.
/// Each of them is the Mir of a constant with the fn's type parameters
/// in scope, but a separate set of locals.
pub promoted: IndexVec<Promoted, Mir<'tcx>>,
/// Yield type of the function, if it is a generator.
pub yield_ty: Option<Ty<'tcx>>,
/// Generator drop glue
pub generator_drop: Option<Box<Mir<'tcx>>>,
/// The layout of a generator. Produced by the state transformation.
pub generator_layout: Option<GeneratorLayout<'tcx>>,
/// 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>,
/// 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,
/// Names and capture modes of all the closure upvars, assuming
/// the first argument is either the closure or a reference to it.
pub upvar_decls: Vec<UpvarDecl>,
/// 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>,
/// A span representing this MIR, for error reporting
pub span: Span,
/// A cache for various calculations
cache: cache::Cache,
}
/// where execution begins
pub const START_BLOCK: BasicBlock = BasicBlock(0);
impl<'tcx> Mir<'tcx> {
pub fn new(
basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
source_scopes: IndexVec<SourceScope, SourceScopeData>,
source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
promoted: IndexVec<Promoted, Mir<'tcx>>,
yield_ty: Option<Ty<'tcx>>,
local_decls: IndexVec<Local, LocalDecl<'tcx>>,
arg_count: usize,
upvar_decls: Vec<UpvarDecl>,
span: Span,
) -> 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()
);
Mir {
basic_blocks,
source_scopes,
source_scope_local_data,
promoted,
yield_ty,
generator_drop: None,
generator_layout: None,
local_decls,
arg_count,
upvar_decls,
spread_arg: None,
span,
cache: cache::Cache::new(),
}
}
#[inline]
pub fn basic_blocks(&self) -> &IndexVec<BasicBlock, BasicBlockData<'tcx>> {
&self.basic_blocks
}
#[inline]
pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
self.cache.invalidate();
&mut self.basic_blocks
}
#[inline]
pub fn basic_blocks_and_local_decls_mut(
&mut self,
) -> (
&mut IndexVec<BasicBlock, BasicBlockData<'tcx>>,
&mut LocalDecls<'tcx>,
) {
self.cache.invalidate();
(&mut self.basic_blocks, &mut self.local_decls)
}
#[inline]
pub fn predecessors(&self) -> ReadGuard<IndexVec<BasicBlock, Vec<BasicBlock>>> {
self.cache.predecessors(self)
}
#[inline]
pub fn predecessors_for(&self, bb: BasicBlock) -> ReadGuard<Vec<BasicBlock>> {
ReadGuard::map(self.predecessors(), |p| &p[bb])
}
#[inline]
pub fn dominators(&self) -> Dominators<BasicBlock> {
dominators(self)
}
#[inline]
pub fn local_kind(&self, local: Local) -> LocalKind {
let index = local.0 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].name.is_some() {
LocalKind::Var
} else {
debug_assert!(
self.local_decls[local].mutability == Mutability::Mut,
"temp should be mutable"
);
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.is_some() {
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);
if self.local_decls[local].is_user_variable.is_some() {
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.is_some() || 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 + 1).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[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!(idx == stmts.len());
&block.terminator().source_info
}
}
/// Check if `sub` is a sub scope of `sup`
pub fn is_sub_scope(&self, mut sub: SourceScope, sup: SourceScope) -> bool {
loop {
if sub == sup {
return true;
}
match self.source_scopes[sub].parent_scope {
None => return false,
Some(p) => sub = p,
}
}
}
/// Return 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
}
}
#[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
pub enum Safety {
Safe,
/// Unsafe because of a PushUnsafeBlock
BuiltinUnsafe,
/// Unsafe because of an unsafe fn
FnUnsafe,
/// Unsafe because of an `unsafe` block
ExplicitUnsafe(ast::NodeId),
}
impl_stable_hash_for!(struct Mir<'tcx> {
basic_blocks,
source_scopes,
source_scope_local_data,
promoted,
yield_ty,
generator_drop,
generator_layout,
local_decls,
arg_count,
upvar_decls,
spread_arg,
span,
cache
});
impl<'tcx> Index<BasicBlock> for Mir<'tcx> {
type Output = BasicBlockData<'tcx>;
#[inline]
fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
&self.basic_blocks()[index]
}
}
impl<'tcx> IndexMut<BasicBlock> for Mir<'tcx> {
#[inline]
fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> {
&mut self.basic_blocks_mut()[index]
}
}
#[derive(Copy, Clone, Debug)]
pub enum ClearCrossCrate<T> {
Clear,
Set(T),
}
impl<T> ClearCrossCrate<T> {
pub fn assert_crate_local(self) -> T {
match self {
ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"),
ClearCrossCrate::Set(v) => v,
}
}
}
impl<T: serialize::Encodable> serialize::UseSpecializedEncodable for ClearCrossCrate<T> {}
impl<T: serialize::Decodable> 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.
#[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
pub struct SourceInfo {
/// 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)]
pub enum Mutability {
Mut,
Not,
}
impl From<Mutability> for hir::Mutability {
fn from(m: Mutability) -> Self {
match m {
Mutability::Mut => hir::MutMutable,
Mutability::Not => hir::MutImmutable,
}
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
pub enum BorrowKind {
/// Data must be immutable and is aliasable.
Shared,
/// 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 you 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 a `&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::Unique => false,
BorrowKind::Mut {
allow_two_phase_borrow,
} => allow_two_phase_borrow,
}
}
}
///////////////////////////////////////////////////////////////////////////
// Variables and temps
newtype_index!(Local
{
DEBUG_FORMAT = "_{}",
const RETURN_PLACE = 0,
});
/// Classifies locals into categories. See `Mir::local_kind`.
#[derive(PartialEq, Eq, Debug)]
pub enum LocalKind {
/// User-declared variable binding
Var,
/// Compiler-introduced temporary
Temp,
/// Function argument
Arg,
/// Location of function's return value
ReturnPointer,
}
#[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
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)>,
}
#[derive(Clone, PartialEq, Eq, Hash, 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,
/// Reference used in a guard expression to ensure immutability.
RefForGuard,
}
CloneTypeFoldableAndLiftImpls! { BindingForm<'tcx>, }
impl_stable_hash_for!(struct self::VarBindingForm<'tcx> {
binding_mode,
opt_ty_info,
opt_match_place
});
mod binding_form_impl {
use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableHasherResult};
use ich::StableHashingContext;
impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
fn hash_stable<W: StableHasherResult>(&self,
hcx: &mut StableHashingContext<'a>,
hasher: &mut StableHasher<W>) {
use super::BindingForm::*;
::std::mem::discriminant(self).hash_stable(hcx, hasher);
match self {
Var(binding) => binding.hash_stable(hcx, hasher),
ImplicitSelf => (),
RefForGuard => (),
}
}
}
}
/// 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)]
pub struct LocalDecl<'tcx> {
/// `let mut x` vs `let x`.
///
/// Temporaries and the return place are always mutable.
pub mutability: Mutability,
/// Some(binding_mode) if this corresponds to a user-declared local variable.
///
/// This is solely used for local diagnostics when generating
/// warnings/errors when compiling the current crate, and
/// therefore it need not be visible across crates. pnkfelix
/// currently hypothesized we *need* to wrap this in a
/// `ClearCrossCrate` as long as it carries as `HirId`.
pub is_user_variable: Option<ClearCrossCrate<BindingForm<'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,
/// Type of this local.
pub ty: Ty<'tcx>,
/// Name of the local, used in debuginfo and pretty-printing.
///
/// Note that function arguments can also have this set to `Some(_)`
/// to generate better debuginfo.
pub name: Option<Name>,
/// 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 `visibility_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.visibility_scope
/// │ │ │← `y + 2`
/// │
/// │ │{ let x: u32 }
/// │ │← x.visibility_scope
/// │ │← `drop(x)` // this accesses `x: u32`
/// ```
pub source_info: SourceInfo,
/// Source scope within which the local is visible (for debuginfo)
/// (see `source_info` for more details).
pub visibility_scope: SourceScope,
}
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.is_user_variable {
Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
binding_mode: ty::BindingMode::BindByValue(_),
opt_ty_info: _,
opt_match_place: _,
}))) => true,
// FIXME: might be able to thread the distinction between
// `self`/`mut self`/`&self`/`&mut self` into the
// `BindingForm::ImplicitSelf` variant, (and then return
// true here for solely the first case).
_ => 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.is_user_variable {
Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
binding_mode: ty::BindingMode::BindByValue(_),
opt_ty_info: _,
opt_match_place: _,
}))) => true,
Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf)) => true,
_ => false,
}
}
/// Create a new `LocalDecl` for a temporary.
#[inline]
pub fn new_temp(ty: Ty<'tcx>, span: Span) -> Self {
LocalDecl {
mutability: Mutability::Mut,
ty,
name: None,
source_info: SourceInfo {
span,
scope: OUTERMOST_SOURCE_SCOPE,
},
visibility_scope: OUTERMOST_SOURCE_SCOPE,
internal: false,
is_user_variable: None,
}
}
/// Create a new `LocalDecl` for a internal temporary.
#[inline]
pub fn new_internal(ty: Ty<'tcx>, span: Span) -> Self {
LocalDecl {
mutability: Mutability::Mut,
ty,
name: None,
source_info: SourceInfo {
span,
scope: OUTERMOST_SOURCE_SCOPE,
},
visibility_scope: OUTERMOST_SOURCE_SCOPE,
internal: true,
is_user_variable: 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,
source_info: SourceInfo {
span,
scope: OUTERMOST_SOURCE_SCOPE,
},
visibility_scope: OUTERMOST_SOURCE_SCOPE,
internal: false,
name: None, // FIXME maybe we do want some name here?
is_user_variable: None,
}
}
}
/// A closure capture, with its name and mode.
#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
pub struct UpvarDecl {
pub debug_name: Name,
/// `HirId` of the captured variable
pub var_hir_id: ClearCrossCrate<HirId>,
/// If true, the capture is behind a reference.
pub by_ref: bool,
pub mutability: Mutability,
}
///////////////////////////////////////////////////////////////////////////
// BasicBlock
newtype_index!(BasicBlock { DEBUG_FORMAT = "bb{}" });
impl BasicBlock {
pub fn start_location(self) -> Location {
Location {
block: self,
statement_index: 0,
}
}
}
///////////////////////////////////////////////////////////////////////////
// BasicBlockData and Terminator
#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
pub struct BasicBlockData<'tcx> {
/// List of statements in this block.
pub statements: Vec<Statement<'tcx>>,
/// Terminator for this block.
///
/// NB. 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)]
pub struct Terminator<'tcx> {
pub source_info: SourceInfo,
pub kind: TerminatorKind<'tcx>,
}
#[derive(Clone, RustcEncodable, RustcDecodable)]
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 {
/// discriminant value being tested
discr: Operand<'tcx>,
/// 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 by the
/// elaboration:
///
/// ```
/// BB0 {
/// DropAndReplace(P <- V, goto BB1, unwind BB2)
/// }
/// ```
///
/// becomes
///
/// ```
/// BB0 {
/// Drop(P, goto BB1, unwind BB2)
/// }
/// BB1 {
/// // P is now unitialized
/// P <- V
/// }
/// BB2 {
/// // P is now unitialized -- 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>,
},
/// 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,
/// The list of blocks control flow could conceptually take, but won't
/// in practice
imaginary_targets: Vec<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_<'a, 'gcx>(
tcx: TyCtxt<'a, 'gcx, '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_targets,
} => Some(real_target).into_iter().chain(&imaginary_targets[..]),
}
}
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_targets,
} => Some(real_target)
.into_iter()
.chain(&mut imaginary_targets[..]),
}
}
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> {
/// Write 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"),
}
}
/// Return 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,
..
} => {
let size = ty::tls::with(|tcx| {
let param_env = ty::ParamEnv::empty();
let switch_ty = tcx.lift_to_global(&switch_ty).unwrap();
tcx.layout_of(param_env.and(switch_ty)).unwrap().size
});
values
.iter()
.map(|&u| {
let mut s = String::new();
print_miri_value(
Scalar::Bits {
bits: u,
size: size.bytes() as u8,
}.to_value(),
switch_ty,
&mut s,
).unwrap();
s.into()
})
.chain(iter::once(String::from("otherwise").into()))
.collect()
}
Call {
destination: Some(_),
cleanup: Some(_),
..
} => vec!["return".into_cow(), "unwind".into_cow()],
Call {
destination: Some(_),
cleanup: None,
..
} => vec!["return".into_cow()],
Call {
destination: None,
cleanup: Some(_),
..
} => vec!["unwind".into_cow()],
Call {
destination: None,
cleanup: None,
..
} => vec![],
Yield { drop: Some(_), .. } => vec!["resume".into_cow(), "drop".into_cow()],
Yield { drop: None, .. } => vec!["resume".into_cow()],
DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => {
vec!["return".into_cow()]
}
DropAndReplace {
unwind: Some(_), ..
}
| Drop {
unwind: Some(_), ..
} => vec!["return".into_cow(), "unwind".into_cow()],
Assert { cleanup: None, .. } => vec!["".into()],
Assert { .. } => vec!["success".into_cow(), "unwind".into_cow()],
FalseEdges {
ref imaginary_targets,
..
} => {
let mut l = vec!["real".into()];
l.resize(imaginary_targets.len() + 1, "imaginary".into());
l
}
FalseUnwind {
unwind: Some(_), ..
} => vec!["real".into(), "cleanup".into()],
FalseUnwind { unwind: None, .. } => vec!["real".into()],
}
}
}
///////////////////////////////////////////////////////////////////////////
// Statements
#[derive(Clone, RustcEncodable, RustcDecodable)]
pub struct Statement<'tcx> {
pub source_info: SourceInfo,
pub kind: StatementKind<'tcx>,
}
impl<'tcx> Statement<'tcx> {
/// 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, RustcEncodable, RustcDecodable)]
pub enum StatementKind<'tcx> {
/// Write the RHS Rvalue to the LHS Place.
Assign(Place<'tcx>, Rvalue<'tcx>),
/// This represents all the reading that a pattern match may do
/// (e.g. inspecting constants and discriminant values).
ReadForMatch(Place<'tcx>),
/// Write the discriminant for a variant to the enum Place.
SetDiscriminant {
place: Place<'tcx>,
variant_index: usize,
},
/// 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),
/// Execute a piece of inline Assembly.
InlineAsm {
asm: Box<InlineAsm>,
outputs: Vec<Place<'tcx>>,
inputs: Vec<Operand<'tcx>>,
},
/// Assert the given places to be valid inhabitants of their type. These statements are
/// currently only interpreted by miri and only generated when "-Z mir-emit-validate" is passed.
/// See <https://internals.rust-lang.org/t/types-as-contracts/5562/73> for more details.
Validate(ValidationOp, Vec<ValidationOperand<'tcx, Place<'tcx>>>),
/// Mark one terminating point of a region scope (i.e. static region).
/// (The starting point(s) arise implicitly from borrows.)
EndRegion(region::Scope),
/// Encodes a user's type assertion. These need to be preserved intact so that NLL can respect
/// them. For example:
///
/// let (a, b): (T, U) = y;
///
/// Here we would insert a `UserAssertTy<(T, U)>(y)` instruction to check that the type of `y`
/// is the right thing.
///
/// `CanonicalTy` is used to capture "inference variables" from the user's types. For example:
///
/// let x: Vec<_> = ...;
/// let y: &u32 = ...;
///
/// would result in `Vec<?0>` and `&'?0 u32` respectively (where `?0` is a canonicalized
/// variable).
UserAssertTy(CanonicalTy<'tcx>, Local),
/// No-op. Useful for deleting instructions without affecting statement indices.
Nop,
}
/// The `ValidationOp` describes what happens with each of the operands of a
/// `Validate` statement.
#[derive(Copy, Clone, RustcEncodable, RustcDecodable, PartialEq, Eq)]
pub enum ValidationOp {
/// Recursively traverse the place following the type and validate that all type
/// invariants are maintained. Furthermore, acquire exclusive/read-only access to the
/// memory reachable from the place.
Acquire,
/// Recursive traverse the *mutable* part of the type and relinquish all exclusive
/// access.
Release,
/// Recursive traverse the *mutable* part of the type and relinquish all exclusive
/// access *until* the given region ends. Then, access will be recovered.
Suspend(region::Scope),
}
impl Debug for ValidationOp {
fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
use self::ValidationOp::*;
match *self {
Acquire => write!(fmt, "Acquire"),
Release => write!(fmt, "Release"),
// (reuse lifetime rendering policy from ppaux.)
Suspend(ref ce) => write!(fmt, "Suspend({})", ty::ReScope(*ce)),
}
}
}
// This is generic so that it can be reused by miri
#[derive(Clone, Hash, PartialEq, Eq, RustcEncodable, RustcDecodable)]
pub struct ValidationOperand<'tcx, T> {
pub place: T,
pub ty: Ty<'tcx>,
pub re: Option<region::Scope>,
pub mutbl: hir::Mutability,
}
impl<'tcx, T: Debug> Debug for ValidationOperand<'tcx, T> {
fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
write!(fmt, "{:?}: {:?}", self.place, self.ty)?;
if let Some(ce) = self.re {
// (reuse lifetime rendering policy from ppaux.)
write!(fmt, "/{}", ty::ReScope(ce))?;
}
if let hir::MutImmutable = self.mutbl {
write!(fmt, " (imm)")?;
}
Ok(())
}
}
impl<'tcx> Debug for Statement<'tcx> {
fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
use self::StatementKind::*;
match self.kind {
Assign(ref place, ref rv) => write!(fmt, "{:?} = {:?}", place, rv),
ReadForMatch(ref place) => write!(fmt, "ReadForMatch({:?})", place),
// (reuse lifetime rendering policy from ppaux.)
EndRegion(ref ce) => write!(fmt, "EndRegion({})", ty::ReScope(*ce)),
Validate(ref op, ref places) => write!(fmt, "Validate({:?}, {:?})", op, places),
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,
ref outputs,
ref inputs,
} => write!(fmt, "asm!({:?} : {:?} : {:?})", asm, outputs, inputs),
UserAssertTy(ref c_ty, ref local) => {
write!(fmt, "UserAssertTy({:?}, {:?})", c_ty, local)
}
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, Hash, RustcEncodable, RustcDecodable)]
pub enum Place<'tcx> {
/// local variable
Local(Local),
/// static or static mut variable
Static(Box<Static<'tcx>>),
/// Constant code promoted to an injected static
Promoted(Box<(Promoted, Ty<'tcx>)>),
/// projection out of a place (access a field, deref a pointer, etc)
Projection(Box<PlaceProjection<'tcx>>),
}
/// The def-id of a static, along with its normalized type (which is
/// stored to avoid requiring normalization when reading MIR).
#[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub struct Static<'tcx> {
pub def_id: DefId,
pub ty: Ty<'tcx>,
}
impl_stable_hash_for!(struct Static<'tcx> {
def_id,
ty
});
/// The `Projection` data structure defines things of the form `B.x`
/// or `*B` or `B[index]`. Note that it is parameterized because it is
/// shared between `Constant` and `Place`. See the aliases
/// `PlaceProjection` etc below.
#[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub struct Projection<'tcx, B, V, T> {
pub base: B,
pub elem: ProjectionElem<'tcx, V, T>,
}
#[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub enum ProjectionElem<'tcx, 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.
Downcast(&'tcx AdtDef, usize),
}
/// Alias for projections as they appear in places, where the base is a place
/// and the index is a local.
pub type PlaceProjection<'tcx> = Projection<'tcx, Place<'tcx>, Local, Ty<'tcx>>;
/// 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<'tcx, Local, Ty<'tcx>>;
newtype_index!(Field { DEBUG_FORMAT = "field[{}]" });
impl<'tcx> Place<'tcx> {
pub fn field(self, f: Field, ty: Ty<'tcx>) -> Place<'tcx> {
self.elem(ProjectionElem::Field(f, ty))
}
pub fn deref(self) -> Place<'tcx> {
self.elem(ProjectionElem::Deref)
}
pub fn downcast(self, adt_def: &'tcx AdtDef, variant_index: usize) -> Place<'tcx> {
self.elem(ProjectionElem::Downcast(adt_def, variant_index))
}
pub fn index(self, index: Local) -> Place<'tcx> {
self.elem(ProjectionElem::Index(index))
}
pub fn elem(self, elem: PlaceElem<'tcx>) -> Place<'tcx> {
Place::Projection(Box::new(PlaceProjection { base: self, elem }))
}
}
impl<'tcx> Debug for Place<'tcx> {
fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
use self::Place::*;
match *self {
Local(id) => write!(fmt, "{:?}", id),
Static(box self::Static { def_id, ty }) => write!(
fmt,
"({}: {:?})",
ty::tls::with(|tcx| tcx.item_path_str(def_id)),
ty
),
Promoted(ref promoted) => write!(fmt, "({:?}: {:?})", promoted.0, promoted.1),
Projection(ref data) => match data.elem {
ProjectionElem::Downcast(ref adt_def, index) => {
write!(fmt, "({:?} as {})", data.base, adt_def.variants[index].name)
}
ProjectionElem::Deref => write!(fmt, "(*{:?})", data.base),
ProjectionElem::Field(field, ty) => {
write!(fmt, "({:?}.{:?}: {:?})", data.base, field.index(), ty)
}
ProjectionElem::Index(ref index) => write!(fmt, "{:?}[{:?}]", data.base, index),
ProjectionElem::ConstantIndex {
offset,
min_length,
from_end: false,
} => write!(fmt, "{:?}[{:?} of {:?}]", data.base, offset, min_length),
ProjectionElem::ConstantIndex {
offset,
min_length,
from_end: true,
} => write!(fmt, "{:?}[-{:?} of {:?}]", data.base, offset, min_length),
ProjectionElem::Subslice { from, to } if to == 0 => {
write!(fmt, "{:?}[{:?}:]", data.base, from)
}
ProjectionElem::Subslice { from, to } if from == 0 => {
write!(fmt, "{:?}[:-{:?}]", data.base, to)
}
ProjectionElem::Subslice { from, to } => {
write!(fmt, "{:?}[{:?}:-{:?}]", data.base, from, to)
}
},
}
}
}
///////////////////////////////////////////////////////////////////////////
// Scopes
newtype_index!(SourceScope
{
DEBUG_FORMAT = "scope[{}]",
const OUTERMOST_SOURCE_SCOPE = 0,
});
#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
pub struct SourceScopeData {
pub span: Span,
pub parent_scope: Option<SourceScope>,
}
#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
pub struct SourceScopeLocalData {
/// A NodeId with lint levels equivalent to this scope's lint levels.
pub lint_root: ast::NodeId,
/// The unsafe block that contains this node.
pub safety: Safety,
}
///////////////////////////////////////////////////////////////////////////
// Operands
/// These are values that can appear inside an rvalue (or an index
/// place). They are intentionally limited to prevent rvalues from
/// being nested in one another.
#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
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>),
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> {
pub fn function_handle<'a>(
tcx: TyCtxt<'a, 'tcx, 'tcx>,
def_id: DefId,
substs: &'tcx Substs<'tcx>,
span: Span,
) -> Self {
let ty = tcx.type_of(def_id).subst(tcx, substs);
Operand::Constant(box Constant {
span,
ty,
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)]
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>),
/// Create 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)]
pub enum CastKind {
Misc,
/// Convert unique, zero-sized type for a fn to fn()
ReifyFnPointer,
/// Convert non capturing closure to fn()
ClosureFnPointer,
/// Convert safe fn() to unsafe fn()
UnsafeFnPointer,
/// "Unsize" -- convert a thin-or-fat pointer to a fat pointer.
/// codegen must figure out the details once full monomorphization
/// is known. For example, this could be used to cast from a
/// `&[i32;N]` to a `&[i32]`, or a `Box<T>` to a `Box<Trait>`
/// (presuming `T: Trait`).
Unsize,
}
#[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
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, usize, &'tcx Substs<'tcx>, Option<usize>),
Closure(DefId, ClosureSubsts<'tcx>),
Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
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)]
pub enum NullOp {
/// Return the size of a value of that type
SizeOf,
/// Create a new uninitialized box for a value of that type
Box,
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
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::Mut { .. } | BorrowKind::Unique => "mut ",
};
// When printing regions, add trailing space if necessary.
let region = if ppaux::verbose() || ppaux::identify_regions() {
let mut region = region.to_string();
if region.len() > 0 {
region.push(' ');
}
region
} else {
// Do not even print 'static
"".to_owned()
};
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, _) => {
let variant_def = &adt_def.variants[variant];
ppaux::parameterized(fmt, substs, variant_def.did, &[])?;
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, _) => ty::tls::with(|tcx| {
if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
let name = if tcx.sess.opts.debugging_opts.span_free_formats {
format!("[closure@{:?}]", node_id)
} else {
format!("[closure@{:?}]", tcx.hir.span(node_id))
};
let mut struct_fmt = fmt.debug_struct(&name);
tcx.with_freevars(node_id, |freevars| {
for (freevar, place) in freevars.iter().zip(places) {
let var_name = tcx.hir.name(freevar.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(node_id) = tcx.hir.as_local_node_id(def_id) {
let name = format!("[generator@{:?}]", tcx.hir.span(node_id));
let mut struct_fmt = fmt.debug_struct(&name);
tcx.with_freevars(node_id, |freevars| {
for (freevar, place) in freevars.iter().zip(places) {
let var_name = tcx.hir.name(freevar.var_id());
struct_fmt.field(&var_name.as_str(), place);
}
struct_fmt.field("$state", &places[freevars.len()]);
for i in (freevars.len() + 1)..places.len() {
struct_fmt
.field(&format!("${}", i - freevars.len() - 1), &places[i]);
}
});
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, Eq, Hash, RustcEncodable, RustcDecodable)]
pub struct Constant<'tcx> {
pub span: Span,
pub ty: Ty<'tcx>,
pub literal: &'tcx ty::Const<'tcx>,
}
newtype_index!(Promoted { DEBUG_FORMAT = "promoted[{}]" });
impl<'tcx> Debug for Constant<'tcx> {
fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
write!(fmt, "const ")?;
fmt_const_val(fmt, self.literal)
}
}
/// Write a `ConstValue` in a way closer to the original source code than the `Debug` output.
pub fn fmt_const_val<W: Write>(fmt: &mut W, const_val: &ty::Const) -> fmt::Result {
if let Some(value) = const_val.to_byval_value() {
print_miri_value(value, const_val.ty, fmt)
} else {
write!(fmt, "{:?}:{}", const_val.val, const_val.ty)
}
}
pub fn print_miri_value<W: Write>(value: Value, ty: Ty, f: &mut W) -> fmt::Result {
use ty::TypeVariants::*;
// print some primitives
if let Value::Scalar(ScalarMaybeUndef::Scalar(Scalar::Bits { bits, .. })) = value {
match ty.sty {
TyBool if bits == 0 => return write!(f, "false"),
TyBool if bits == 1 => return write!(f, "true"),
TyFloat(ast::FloatTy::F32) => return write!(f, "{}f32", Single::from_bits(bits)),
TyFloat(ast::FloatTy::F64) => return write!(f, "{}f64", Double::from_bits(bits)),
TyUint(ui) => return write!(f, "{:?}{}", bits, ui),
TyInt(i) => {
let bit_width = ty::tls::with(|tcx| {
let ty = tcx.lift_to_global(&ty).unwrap();
tcx.layout_of(ty::ParamEnv::empty().and(ty))
.unwrap()
.size
.bits()
});
let shift = 128 - bit_width;
return write!(f, "{:?}{}", ((bits as i128) << shift) >> shift, i);
}
TyChar => return write!(f, "{:?}", ::std::char::from_u32(bits as u32).unwrap()),
_ => {},
}
}
// print function definitons
if let TyFnDef(did, _) = ty.sty {
return write!(f, "{}", item_path_str(did));
}
// print string literals
if let Value::ScalarPair(ptr, len) = value {
if let ScalarMaybeUndef::Scalar(Scalar::Ptr(ptr)) = ptr {
if let ScalarMaybeUndef::Scalar(Scalar::Bits { bits: len, .. }) = len {
if let TyRef(_, &ty::TyS { sty: TyStr, .. }, _) = ty.sty {
return ty::tls::with(|tcx| {
let alloc = tcx.alloc_map.lock().get(ptr.alloc_id);
if let Some(interpret::AllocType::Memory(alloc)) = alloc {
assert_eq!(len as usize as u128, len);
let slice = &alloc
.bytes
[(ptr.offset.bytes() as usize)..]
[..(len as usize)];
let s = ::std::str::from_utf8(slice).expect("non utf8 str from miri");
write!(f, "{:?}", s)
} else {
write!(f, "pointer to erroneous constant {:?}, {:?}", ptr, len)
}
});
}
}
}
}
// just raw dump everything else
write!(f, "{:?}:{}", value, ty)
}
fn item_path_str(def_id: DefId) -> String {
ty::tls::with(|tcx| tcx.item_path_str(def_id))
}
impl<'tcx> graph::DirectedGraph for Mir<'tcx> {
type Node = BasicBlock;
}
impl<'tcx> graph::WithNumNodes for Mir<'tcx> {
fn num_nodes(&self) -> usize {
self.basic_blocks.len()
}
}
impl<'tcx> graph::WithStartNode for Mir<'tcx> {
fn start_node(&self) -> Self::Node {
START_BLOCK
}
}
impl<'tcx> graph::WithPredecessors for Mir<'tcx> {
fn predecessors<'graph>(
&'graph self,
node: Self::Node,
) -> <Self as GraphPredecessors<'graph>>::Iter {
self.predecessors_for(node).clone().into_iter()
}
}
impl<'tcx> graph::WithSuccessors for Mir<'tcx> {
fn successors<'graph>(
&'graph self,
node: Self::Node,
) -> <Self as GraphSuccessors<'graph>>::Iter {
self.basic_blocks[node].terminator().successors().cloned()
}
}
impl<'a, 'b> graph::GraphPredecessors<'b> for Mir<'a> {
type Item = BasicBlock;
type Iter = IntoIter<BasicBlock>;
}
impl<'a, 'b> graph::GraphSuccessors<'b> for Mir<'a> {
type Item = BasicBlock;
type Iter = iter::Cloned<Successors<'b>>;
}
#[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
pub struct Location {
/// the location is within this block
pub block: BasicBlock,
/// the location is the start of the statement; or, if `statement_index`
/// == num-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,
}
}
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, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub enum UnsafetyViolationKind {
General,
ExternStatic(ast::NodeId),
BorrowPacked(ast::NodeId),
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub struct UnsafetyViolation {
pub source_info: SourceInfo,
pub description: InternedString,
pub details: InternedString,
pub kind: UnsafetyViolationKind,
}
#[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
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<[(ast::NodeId, bool)]>,
}
/// The layout of generator state
#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
pub struct GeneratorLayout<'tcx> {
pub fields: Vec<LocalDecl<'tcx>>,
}
#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
pub struct BorrowCheckResult<'gcx> {
pub closure_requirements: Option<ClosureRegionRequirements<'gcx>>,
pub used_mut_upvars: SmallVec<[Field; 8]>,
}
/// 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)]
pub struct ClosureRegionRequirements<'gcx> {
/// 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<'gcx>>,
}
/// Indicates an outlives constraint between a type or between two
/// free-regions declared on the closure.
#[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
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,
}
/// The subject of a ClosureOutlivesRequirement -- that is, the thing
/// that must outlive some region.
#[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
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! {
Mutability,
SourceInfo,
UpvarDecl,
ValidationOp,
SourceScope,
SourceScopeData,
SourceScopeLocalData,
}
BraceStructTypeFoldableImpl! {
impl<'tcx> TypeFoldable<'tcx> for Mir<'tcx> {
basic_blocks,
source_scopes,
source_scope_local_data,
promoted,
yield_ty,
generator_drop,
generator_layout,
local_decls,
arg_count,
upvar_decls,
spread_arg,
span,
cache,
}
}
BraceStructTypeFoldableImpl! {
impl<'tcx> TypeFoldable<'tcx> for GeneratorLayout<'tcx> {
fields
}
}
BraceStructTypeFoldableImpl! {
impl<'tcx> TypeFoldable<'tcx> for LocalDecl<'tcx> {
mutability,
is_user_variable,
internal,
ty,
name,
source_info,
visibility_scope,
}
}
BraceStructTypeFoldableImpl! {
impl<'tcx> TypeFoldable<'tcx> for BasicBlockData<'tcx> {
statements,
terminator,
is_cleanup,
}
}
BraceStructTypeFoldableImpl! {
impl<'tcx> TypeFoldable<'tcx> for ValidationOperand<'tcx, Place<'tcx>> {
place, ty, re, mutbl
}
}
BraceStructTypeFoldableImpl! {
impl<'tcx> TypeFoldable<'tcx> for Statement<'tcx> {
source_info, kind
}
}
EnumTypeFoldableImpl! {
impl<'tcx> TypeFoldable<'tcx> for StatementKind<'tcx> {
(StatementKind::Assign)(a, b),
(StatementKind::ReadForMatch)(place),
(StatementKind::SetDiscriminant) { place, variant_index },
(StatementKind::StorageLive)(a),
(StatementKind::StorageDead)(a),
(StatementKind::InlineAsm) { asm, outputs, inputs },
(StatementKind::Validate)(a, b),
(StatementKind::EndRegion)(a),
(StatementKind::UserAssertTy)(a, b),
(StatementKind::Nop),
}
}
EnumTypeFoldableImpl! {
impl<'tcx, T> TypeFoldable<'tcx> for ClearCrossCrate<T> {
(ClearCrossCrate::Clear),
(ClearCrossCrate::Set)(a),
} where T: TypeFoldable<'tcx>
}
impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
use mir::TerminatorKind::*;
let kind = match self.kind {
Goto { target } => Goto { target: 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,
} => {
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,
}
}
Assert {
ref cond,
expected,
ref msg,
target,
cleanup,
} => {
let msg = if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
EvalErrorKind::BoundsCheck {
len: len.fold_with(folder),
index: index.fold_with(folder),
}
} else {
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,
ref imaginary_targets,
} => FalseEdges {
real_target,
imaginary_targets: imaginary_targets.clone(),
},
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 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) {
if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
len.visit_with(visitor) || index.visit_with(visitor)
} else {
false
}
} else {
false
}
}
Goto { .. }
| Resume
| Abort
| Return
| GeneratorDrop
| Unreachable
| FalseEdges { .. }
| FalseUnwind { .. } => false,
}
}
}
impl<'tcx> TypeFoldable<'tcx> for Place<'tcx> {
fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
match self {
&Place::Projection(ref p) => Place::Projection(p.fold_with(folder)),
_ => self.clone(),
}
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
if let &Place::Projection(ref p) = self {
p.visit_with(visitor)
} else {
false
}
}
}
impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
use 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, n) => {
AggregateKind::Adt(def, v, substs.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 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, _) => substs.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<'gcx: 'tcx, F: TypeFolder<'gcx, '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, B, V, T> TypeFoldable<'tcx> for Projection<'tcx, B, V, T>
where
B: TypeFoldable<'tcx>,
V: TypeFoldable<'tcx>,
T: TypeFoldable<'tcx>,
{
fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
use mir::ProjectionElem::*;
let base = self.base.fold_with(folder);
let elem = match self.elem {
Deref => Deref,
Field(f, ref ty) => Field(f, ty.fold_with(folder)),
Index(ref v) => Index(v.fold_with(folder)),
ref elem => elem.clone(),
};
Projection { base, elem }
}
fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool {
use mir::ProjectionElem::*;
self.base.visit_with(visitor) || match self.elem {
Field(_, ref ty) => ty.visit_with(visitor),
Index(ref v) => v.visit_with(visitor),
_ => false,
}
}
}
impl<'tcx> TypeFoldable<'tcx> for Field {
fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _: &mut F) -> Self {
*self
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
false
}
}
impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> {
fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
Constant {
span: self.span.clone(),
ty: self.ty.fold_with(folder),
literal: self.literal.fold_with(folder),
}
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
self.ty.visit_with(visitor) || self.literal.visit_with(visitor)
}
}