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fuchsia / third_party / rust / 03534ac8b70de1134ce7e91b172cd629048a6c8b / . / compiler / rustc_middle / src / mir / mod.rs
blob: 34e47de969c1750c26cff908bbd1d61b40f8c389 [file] [log] [blame]
//! MIR datatypes and passes. See the [rustc dev guide] for more info.
//!
//! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/mir/index.html
use crate::mir::interpret::{
AllocRange, ConstAllocation, ConstValue, ErrorHandled, GlobalAlloc, LitToConstInput, Scalar,
};
use crate::mir::visit::MirVisitable;
use crate::ty::codec::{TyDecoder, TyEncoder};
use crate::ty::fold::{FallibleTypeFolder, TypeFoldable};
use crate::ty::print::{FmtPrinter, Printer};
use crate::ty::visit::TypeVisitableExt;
use crate::ty::{self, List, Ty, TyCtxt};
use crate::ty::{AdtDef, InstanceDef, ScalarInt, UserTypeAnnotationIndex};
use crate::ty::{GenericArg, InternalSubsts, SubstsRef};
use rustc_data_structures::captures::Captures;
use rustc_errors::ErrorGuaranteed;
use rustc_hir::def::{CtorKind, Namespace};
use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID};
use rustc_hir::{self, GeneratorKind, ImplicitSelfKind};
use rustc_hir::{self as hir, HirId};
use rustc_session::Session;
use rustc_target::abi::{FieldIdx, Size, VariantIdx};
use polonius_engine::Atom;
pub use rustc_ast::Mutability;
use rustc_data_structures::fx::FxHashSet;
use rustc_data_structures::graph::dominators::Dominators;
use rustc_index::{Idx, IndexSlice, IndexVec};
use rustc_serialize::{Decodable, Encodable};
use rustc_span::symbol::Symbol;
use rustc_span::{Span, DUMMY_SP};
use either::Either;
use std::borrow::Cow;
use std::fmt::{self, Debug, Display, Formatter, Write};
use std::ops::{Index, IndexMut};
use std::{iter, mem};
pub use self::query::*;
pub use basic_blocks::BasicBlocks;
mod basic_blocks;
pub mod coverage;
mod generic_graph;
pub mod generic_graphviz;
pub mod graphviz;
pub mod interpret;
pub mod mono;
pub mod patch;
pub mod pretty;
mod query;
pub mod spanview;
mod syntax;
pub use syntax::*;
pub mod tcx;
pub mod terminator;
pub use terminator::*;
pub mod traversal;
mod type_foldable;
pub mod visit;
pub use self::generic_graph::graphviz_safe_def_name;
pub use self::graphviz::write_mir_graphviz;
pub use self::pretty::{
create_dump_file, display_allocation, dump_enabled, dump_mir, write_mir_pretty, PassWhere,
};
/// Types for locals
pub type LocalDecls<'tcx> = IndexSlice<Local, LocalDecl<'tcx>>;
pub trait HasLocalDecls<'tcx> {
fn local_decls(&self) -> &LocalDecls<'tcx>;
}
impl<'tcx> HasLocalDecls<'tcx> for IndexVec<Local, LocalDecl<'tcx>> {
#[inline]
fn local_decls(&self) -> &LocalDecls<'tcx> {
self
}
}
impl<'tcx> HasLocalDecls<'tcx> for LocalDecls<'tcx> {
#[inline]
fn local_decls(&self) -> &LocalDecls<'tcx> {
self
}
}
impl<'tcx> HasLocalDecls<'tcx> for Body<'tcx> {
#[inline]
fn local_decls(&self) -> &LocalDecls<'tcx> {
&self.local_decls
}
}
/// A streamlined trait that you can implement to create a pass; the
/// pass will be named after the type, and it will consist of a main
/// loop that goes over each available MIR and applies `run_pass`.
pub trait MirPass<'tcx> {
fn name(&self) -> &'static str {
let name = std::any::type_name::<Self>();
if let Some((_, tail)) = name.rsplit_once(':') { tail } else { name }
}
/// Returns `true` if this pass is enabled with the current combination of compiler flags.
fn is_enabled(&self, _sess: &Session) -> bool {
true
}
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>);
fn is_mir_dump_enabled(&self) -> bool {
true
}
}
impl MirPhase {
/// Gets the index of the current MirPhase within the set of all `MirPhase`s.
///
/// FIXME(JakobDegen): Return a `(usize, usize)` instead.
pub fn phase_index(&self) -> usize {
const BUILT_PHASE_COUNT: usize = 1;
const ANALYSIS_PHASE_COUNT: usize = 2;
match self {
MirPhase::Built => 1,
MirPhase::Analysis(analysis_phase) => {
1 + BUILT_PHASE_COUNT + (*analysis_phase as usize)
}
MirPhase::Runtime(runtime_phase) => {
1 + BUILT_PHASE_COUNT + ANALYSIS_PHASE_COUNT + (*runtime_phase as usize)
}
}
}
/// Parses an `MirPhase` from a pair of strings. Panics if this isn't possible for any reason.
pub fn parse(dialect: String, phase: Option<String>) -> Self {
match &*dialect.to_ascii_lowercase() {
"built" => {
assert!(phase.is_none(), "Cannot specify a phase for `Built` MIR");
MirPhase::Built
}
"analysis" => Self::Analysis(AnalysisPhase::parse(phase)),
"runtime" => Self::Runtime(RuntimePhase::parse(phase)),
_ => panic!("Unknown MIR dialect {}", dialect),
}
}
}
impl AnalysisPhase {
pub fn parse(phase: Option<String>) -> Self {
let Some(phase) = phase else {
return Self::Initial;
};
match &*phase.to_ascii_lowercase() {
"initial" => Self::Initial,
"post_cleanup" | "post-cleanup" | "postcleanup" => Self::PostCleanup,
_ => panic!("Unknown analysis phase {}", phase),
}
}
}
impl RuntimePhase {
pub fn parse(phase: Option<String>) -> Self {
let Some(phase) = phase else {
return Self::Initial;
};
match &*phase.to_ascii_lowercase() {
"initial" => Self::Initial,
"post_cleanup" | "post-cleanup" | "postcleanup" => Self::PostCleanup,
"optimized" => Self::Optimized,
_ => panic!("Unknown runtime phase {}", phase),
}
}
}
/// Where a specific `mir::Body` comes from.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
#[derive(HashStable, TyEncodable, TyDecodable, TypeFoldable, TypeVisitable)]
pub struct MirSource<'tcx> {
pub instance: InstanceDef<'tcx>,
/// If `Some`, this is a promoted rvalue within the parent function.
pub promoted: Option<Promoted>,
}
impl<'tcx> MirSource<'tcx> {
pub fn item(def_id: DefId) -> Self {
MirSource { instance: InstanceDef::Item(def_id), promoted: None }
}
pub fn from_instance(instance: InstanceDef<'tcx>) -> Self {
MirSource { instance, promoted: None }
}
#[inline]
pub fn def_id(&self) -> DefId {
self.instance.def_id()
}
}
#[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable, TypeVisitable)]
pub struct GeneratorInfo<'tcx> {
/// The yield type of the function, if it is a generator.
pub yield_ty: Option<Ty<'tcx>>,
/// Generator drop glue.
pub generator_drop: Option<Body<'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: GeneratorKind,
}
/// The lowered representation of a single function.
#[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable, TypeVisitable)]
pub struct Body<'tcx> {
/// A list of basic blocks. References to basic block use a newtyped index type [`BasicBlock`]
/// that indexes into this vector.
pub basic_blocks: BasicBlocks<'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,
/// How many passses we have executed since starting the current phase. Used for debug output.
pub pass_count: usize,
pub source: MirSource<'tcx>,
/// A list of source scopes; these are referenced by statements
/// and used for debuginfo. Indexed by a `SourceScope`.
pub source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
pub generator: Option<Box<GeneratorInfo<'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: IndexVec<Local, LocalDecl<'tcx>>,
/// User type annotations.
pub user_type_annotations: ty::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>>,
/// A span representing this MIR, for error reporting.
pub span: Span,
/// Constants that are required to evaluate successfully for this MIR to be well-formed.
/// We hold in this field all the constants we are not able to evaluate yet.
pub required_consts: Vec<Constant<'tcx>>,
/// Does this body use generic parameters. This is used for the `ConstEvaluatable` check.
///
/// Note that this does not actually mean that this body is not computable right now.
/// The repeat count in the following example is polymorphic, but can still be evaluated
/// without knowing anything about the type parameter `T`.
///
/// ```rust
/// fn test<T>() {
/// let _ = [0; std::mem::size_of::<*mut T>()];
/// }
/// ```
///
/// **WARNING**: Do not change this flags after the MIR was originally created, even if an optimization
/// removed the last mention of all generic params. We do not want to rely on optimizations and
/// potentially allow things like `[u8; std::mem::size_of::<T>() * 0]` due to this.
pub is_polymorphic: bool,
/// The phase at which this MIR should be "injected" into the compilation process.
///
/// Everything that comes before this `MirPhase` should be skipped.
///
/// This is only `Some` if the function that this body comes from was annotated with `rustc_custom_mir`.
pub injection_phase: Option<MirPhase>,
pub tainted_by_errors: Option<ErrorGuaranteed>,
}
impl<'tcx> Body<'tcx> {
pub fn new(
source: MirSource<'tcx>,
basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
local_decls: IndexVec<Local, LocalDecl<'tcx>>,
user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
arg_count: usize,
var_debug_info: Vec<VarDebugInfo<'tcx>>,
span: Span,
generator_kind: Option<GeneratorKind>,
tainted_by_errors: Option<ErrorGuaranteed>,
) -> Self {
// We need `arg_count` locals, and one for the return place.
assert!(
local_decls.len() > arg_count,
"expected at least {} locals, got {}",
arg_count + 1,
local_decls.len()
);
let mut body = Body {
phase: MirPhase::Built,
pass_count: 0,
source,
basic_blocks: BasicBlocks::new(basic_blocks),
source_scopes,
generator: generator_kind.map(|generator_kind| {
Box::new(GeneratorInfo {
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,
required_consts: Vec::new(),
is_polymorphic: false,
injection_phase: None,
tainted_by_errors,
};
body.is_polymorphic = body.has_non_region_param();
body
}
/// Returns a partially initialized MIR body containing only a list of basic blocks.
///
/// The returned MIR contains no `LocalDecl`s (even for the return place) or source scopes. It
/// is only useful for testing but cannot be `#[cfg(test)]` because it is used in a different
/// crate.
pub fn new_cfg_only(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>) -> Self {
let mut body = Body {
phase: MirPhase::Built,
pass_count: 0,
source: MirSource::item(CRATE_DEF_ID.to_def_id()),
basic_blocks: BasicBlocks::new(basic_blocks),
source_scopes: IndexVec::new(),
generator: None,
local_decls: IndexVec::new(),
user_type_annotations: IndexVec::new(),
arg_count: 0,
spread_arg: None,
span: DUMMY_SP,
required_consts: Vec::new(),
var_debug_info: Vec::new(),
is_polymorphic: false,
injection_phase: None,
tainted_by_errors: None,
};
body.is_polymorphic = body.has_non_region_param();
body
}
#[inline]
pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
self.basic_blocks.as_mut()
}
#[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 {
LocalKind::Temp
}
}
/// Returns an iterator over all user-declared mutable locals.
#[inline]
pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + Captures<'tcx> + 'a {
(self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
let local = Local::new(index);
let decl = &self.local_decls[local];
(decl.is_user_variable() && decl.mutability.is_mut()).then_some(local)
})
}
/// 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> + Captures<'tcx> + '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> + ExactSizeIterator {
(1..self.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 DoubleEndedIterator<Item = Local> + ExactSizeIterator {
(self.arg_count + 1..self.local_decls.len()).map(Local::new)
}
#[inline]
pub fn drain_vars_and_temps<'a>(&'a mut self) -> impl Iterator<Item = LocalDecl<'tcx>> + 'a {
self.local_decls.drain(self.arg_count + 1..)
}
/// 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
}
}
/// Returns the return type; it always return first element from `local_decls` array.
#[inline]
pub fn return_ty(&self) -> Ty<'tcx> {
self.local_decls[RETURN_PLACE].ty
}
/// Returns the return type; it always return first element from `local_decls` array.
#[inline]
pub fn bound_return_ty(&self) -> ty::EarlyBinder<Ty<'tcx>> {
ty::EarlyBinder::new(self.local_decls[RETURN_PLACE].ty)
}
/// Gets the location of the terminator for the given block.
#[inline]
pub fn terminator_loc(&self, bb: BasicBlock) -> Location {
Location { block: bb, statement_index: self[bb].statements.len() }
}
pub fn stmt_at(&self, location: Location) -> Either<&Statement<'tcx>, &Terminator<'tcx>> {
let Location { block, statement_index } = location;
let block_data = &self.basic_blocks[block];
block_data
.statements
.get(statement_index)
.map(Either::Left)
.unwrap_or_else(|| Either::Right(block_data.terminator()))
}
#[inline]
pub fn yield_ty(&self) -> Option<Ty<'tcx>> {
self.generator.as_ref().and_then(|generator| generator.yield_ty)
}
#[inline]
pub fn generator_layout(&self) -> Option<&GeneratorLayout<'tcx>> {
self.generator.as_ref().and_then(|generator| generator.generator_layout.as_ref())
}
#[inline]
pub fn generator_drop(&self) -> Option<&Body<'tcx>> {
self.generator.as_ref().and_then(|generator| generator.generator_drop.as_ref())
}
#[inline]
pub fn generator_kind(&self) -> Option<GeneratorKind> {
self.generator.as_ref().map(|generator| generator.generator_kind)
}
#[inline]
pub fn should_skip(&self) -> bool {
let Some(injection_phase) = self.injection_phase else {
return false;
};
injection_phase > self.phase
}
#[inline]
pub fn is_custom_mir(&self) -> bool {
self.injection_phase.is_some()
}
}
#[derive(Copy, Clone, PartialEq, Eq, Debug, TyEncodable, TyDecodable, HashStable)]
pub enum Safety {
Safe,
/// Unsafe because of compiler-generated unsafe code, like `await` desugaring
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]
}
}
impl<'tcx> IndexMut<BasicBlock> for Body<'tcx> {
#[inline]
fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> {
&mut self.basic_blocks.as_mut()[index]
}
}
#[derive(Copy, Clone, Debug, HashStable, TypeFoldable, TypeVisitable)]
pub enum ClearCrossCrate<T> {
Clear,
Set(T),
}
impl<T> ClearCrossCrate<T> {
pub fn as_ref(&self) -> ClearCrossCrate<&T> {
match self {
ClearCrossCrate::Clear => ClearCrossCrate::Clear,
ClearCrossCrate::Set(v) => ClearCrossCrate::Set(v),
}
}
pub fn as_mut(&mut self) -> ClearCrossCrate<&mut 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,
}
}
}
const TAG_CLEAR_CROSS_CRATE_CLEAR: u8 = 0;
const TAG_CLEAR_CROSS_CRATE_SET: u8 = 1;
impl<E: TyEncoder, T: Encodable<E>> Encodable<E> for ClearCrossCrate<T> {
#[inline]
fn encode(&self, e: &mut E) {
if E::CLEAR_CROSS_CRATE {
return;
}
match *self {
ClearCrossCrate::Clear => TAG_CLEAR_CROSS_CRATE_CLEAR.encode(e),
ClearCrossCrate::Set(ref val) => {
TAG_CLEAR_CROSS_CRATE_SET.encode(e);
val.encode(e);
}
}
}
}
impl<D: TyDecoder, T: Decodable<D>> Decodable<D> for ClearCrossCrate<T> {
#[inline]
fn decode(d: &mut D) -> ClearCrossCrate<T> {
if D::CLEAR_CROSS_CRATE {
return ClearCrossCrate::Clear;
}
let discr = u8::decode(d);
match discr {
TAG_CLEAR_CROSS_CRATE_CLEAR => ClearCrossCrate::Clear,
TAG_CLEAR_CROSS_CRATE_SET => {
let val = T::decode(d);
ClearCrossCrate::Set(val)
}
tag => panic!("Invalid tag for ClearCrossCrate: {:?}", tag),
}
}
}
/// 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, TyEncodable, TyDecodable, 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,
}
impl SourceInfo {
#[inline]
pub fn outermost(span: Span) -> Self {
SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE }
}
}
///////////////////////////////////////////////////////////////////////////
// Variables and temps
rustc_index::newtype_index! {
#[derive(HashStable)]
#[debug_format = "_{}"]
pub struct Local {
const RETURN_PLACE = 0;
}
}
impl Atom for Local {
fn index(self) -> usize {
Idx::index(self)
}
}
/// Classifies locals into categories. See `Body::local_kind`.
#[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable)]
pub enum LocalKind {
/// User-declared variable binding or compiler-introduced temporary.
Temp,
/// Function argument.
Arg,
/// Location of function's return value.
ReturnPointer,
}
#[derive(Clone, Debug, TyEncodable, TyDecodable, 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, TyEncodable, TyDecodable)]
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,
}
TrivialTypeTraversalAndLiftImpls! {
BindingForm<'tcx>,
}
mod binding_form_impl {
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_query_system::ich::StableHashingContext;
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, TyEncodable, TyDecodable, 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,
/// `Span` of the tail expression.
pub span: Span,
}
/// 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, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
pub struct LocalDecl<'tcx> {
/// Whether this is a mutable binding (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: ClearCrossCrate<Box<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
/// outside of type inference.
///
/// This should be sound because the drop flags are fully algebraic, and
/// therefore don't affect the auto-trait or outlives properties of the
/// generator.
pub internal: bool,
/// 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: Option<Box<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::<u32>().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 some locals that's used for diagnostics and for
/// classifying variables into local variables, statics, etc, which is needed e.g.
/// for unsafety checking.
///
/// Not used for non-StaticRef temporaries, the return place, or anonymous
/// function parameters.
#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
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(BindingForm<'tcx>),
/// A temporary created that references the static with the given `DefId`.
StaticRef { def_id: DefId, is_thread_local: bool },
/// A temporary created that references the const with the given `DefId`
ConstRef { def_id: DefId },
/// A temporary created during the creation of an aggregate
/// (e.g. a temporary for `foo` in `MyStruct { my_field: foo }`)
AggregateTemp,
/// 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`
BlockTailTemp(BlockTailInfo),
/// A temporary created during the pass `Derefer` to avoid it's retagging
DerefTemp,
/// A temporary created for borrow checking.
FakeBorrow,
/// A local without anything interesting about it.
Boring,
}
impl<'tcx> LocalDecl<'tcx> {
pub fn local_info(&self) -> &LocalInfo<'tcx> {
&self.local_info.as_ref().assert_crate_local()
}
/// 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 {
matches!(
self.local_info(),
LocalInfo::User(
BindingForm::Var(VarBindingForm {
binding_mode: ty::BindingMode::BindByValue(_),
opt_ty_info: _,
opt_match_place: _,
pat_span: _,
}) | BindingForm::ImplicitSelf(ImplicitSelfKind::Imm),
)
)
}
/// 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 {
matches!(
self.local_info(),
LocalInfo::User(
BindingForm::Var(VarBindingForm {
binding_mode: ty::BindingMode::BindByValue(_),
opt_ty_info: _,
opt_match_place: _,
pat_span: _,
}) | BindingForm::ImplicitSelf(_),
)
)
}
/// Returns `true` if this variable is a named variable or function
/// parameter declared by the user.
#[inline]
pub fn is_user_variable(&self) -> bool {
matches!(self.local_info(), LocalInfo::User(_))
}
/// 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 {
matches!(self.local_info(), LocalInfo::User(BindingForm::RefForGuard))
}
/// 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 {
matches!(self.local_info(), LocalInfo::StaticRef { .. })
}
/// Returns `Some` if this is a reference to a thread-local 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` if this is a DerefTemp
pub fn is_deref_temp(&self) -> bool {
match self.local_info() {
LocalInfo::DerefTemp => return true,
_ => (),
}
return 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: mutable, non-internal.
#[inline]
pub fn new(ty: Ty<'tcx>, span: Span) -> Self {
Self::with_source_info(ty, SourceInfo::outermost(span))
}
/// Like `LocalDecl::new`, but takes a `SourceInfo` instead of a `Span`.
#[inline]
pub fn with_source_info(ty: Ty<'tcx>, source_info: SourceInfo) -> Self {
LocalDecl {
mutability: Mutability::Mut,
local_info: ClearCrossCrate::Set(Box::new(LocalInfo::Boring)),
internal: false,
ty,
user_ty: None,
source_info,
}
}
/// Converts `self` into same `LocalDecl` except tagged as internal.
#[inline]
pub fn internal(mut self) -> Self {
self.internal = true;
self
}
/// Converts `self` into same `LocalDecl` except tagged as immutable.
#[inline]
pub fn immutable(mut self) -> Self {
self.mutability = Mutability::Not;
self
}
}
#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
pub enum VarDebugInfoContents<'tcx> {
/// This `Place` only contains projection which satisfy `can_use_in_debuginfo`.
Place(Place<'tcx>),
Const(Constant<'tcx>),
/// The user variable's data is split across several fragments,
/// each described by a `VarDebugInfoFragment`.
/// See DWARF 5's "2.6.1.2 Composite Location Descriptions"
/// and LLVM's `DW_OP_LLVM_fragment` for more details on
/// the underlying debuginfo feature this relies on.
Composite {
/// Type of the original user variable.
/// This cannot contain a union or an enum.
ty: Ty<'tcx>,
/// All the parts of the original user variable, which ended
/// up in disjoint places, due to optimizations.
fragments: Vec<VarDebugInfoFragment<'tcx>>,
},
}
impl<'tcx> Debug for VarDebugInfoContents<'tcx> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
match self {
VarDebugInfoContents::Const(c) => write!(fmt, "{}", c),
VarDebugInfoContents::Place(p) => write!(fmt, "{:?}", p),
VarDebugInfoContents::Composite { ty, fragments } => {
write!(fmt, "{:?}{{ ", ty)?;
for f in fragments.iter() {
write!(fmt, "{:?}, ", f)?;
}
write!(fmt, "}}")
}
}
}
}
#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
pub struct VarDebugInfoFragment<'tcx> {
/// Where in the composite user variable this fragment is,
/// represented as a "projection" into the composite variable.
/// At lower levels, this corresponds to a byte/bit range.
///
/// This can only contain `PlaceElem::Field`.
// FIXME support this for `enum`s by either using DWARF's
// more advanced control-flow features (unsupported by LLVM?)
// to match on the discriminant, or by using custom type debuginfo
// with non-overlapping variants for the composite variable.
pub projection: Vec<PlaceElem<'tcx>>,
/// Where the data for this fragment can be found.
/// This `Place` only contains projection which satisfy `can_use_in_debuginfo`.
pub contents: Place<'tcx>,
}
impl Debug for VarDebugInfoFragment<'_> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
for elem in self.projection.iter() {
match elem {
ProjectionElem::Field(field, _) => {
write!(fmt, ".{:?}", field.index())?;
}
_ => bug!("unsupported fragment projection `{:?}`", elem),
}
}
write!(fmt, " => {:?}", self.contents)
}
}
/// Debug information pertaining to a user variable.
#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
pub struct VarDebugInfo<'tcx> {
pub name: Symbol,
/// 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.
pub value: VarDebugInfoContents<'tcx>,
/// When present, indicates what argument number this variable is in the function that it
/// originated from (starting from 1). Note, if MIR inlining is enabled, then this is the
/// argument number in the original function before it was inlined.
pub argument_index: Option<u16>,
/// The data represents `name` dereferenced `references` times,
/// and not the direct value.
pub references: u8,
}
///////////////////////////////////////////////////////////////////////////
// BasicBlock
rustc_index::newtype_index! {
/// A node in the MIR [control-flow graph][CFG].
///
/// There are no branches (e.g., `if`s, function calls, etc.) within a basic block, which makes
/// it easier to do [data-flow analyses] and optimizations. Instead, branches are represented
/// as an edge in a graph between basic blocks.
///
/// Basic blocks consist of a series of [statements][Statement], ending with a
/// [terminator][Terminator]. Basic blocks can have multiple predecessors and successors,
/// however there is a MIR pass ([`CriticalCallEdges`]) that removes *critical edges*, which
/// are edges that go from a multi-successor node to a multi-predecessor node. This pass is
/// needed because some analyses require that there are no critical edges in the CFG.
///
/// Note that this type is just an index into [`Body.basic_blocks`](Body::basic_blocks);
/// the actual data that a basic block holds is in [`BasicBlockData`].
///
/// Read more about basic blocks in the [rustc-dev-guide][guide-mir].
///
/// [CFG]: https://rustc-dev-guide.rust-lang.org/appendix/background.html#cfg
/// [data-flow analyses]:
/// https://rustc-dev-guide.rust-lang.org/appendix/background.html#what-is-a-dataflow-analysis
/// [`CriticalCallEdges`]: ../../rustc_const_eval/transform/add_call_guards/enum.AddCallGuards.html#variant.CriticalCallEdges
/// [guide-mir]: https://rustc-dev-guide.rust-lang.org/mir/
#[derive(HashStable)]
#[debug_format = "bb{}"]
pub struct BasicBlock {
const START_BLOCK = 0;
}
}
impl BasicBlock {
pub fn start_location(self) -> Location {
Location { block: self, statement_index: 0 }
}
}
///////////////////////////////////////////////////////////////////////////
// BasicBlockData
/// Data for a basic block, including a list of its statements.
///
/// See [`BasicBlock`] for documentation on what basic blocks are at a high level.
#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
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,
}
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 convenient way to reach the terminator.
#[inline]
pub fn terminator(&self) -> &Terminator<'tcx> {
self.terminator.as_ref().expect("invalid terminator state")
}
#[inline]
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::outermost(DUMMY_SP), 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 }
}
/// Does the block have no statements and an unreachable terminator?
pub fn is_empty_unreachable(&self) -> bool {
self.statements.is_empty() && matches!(self.terminator().kind, TerminatorKind::Unreachable)
}
}
impl<O> AssertKind<O> {
/// Returns true if this an overflow checking assertion controlled by -C overflow-checks.
pub fn is_optional_overflow_check(&self) -> bool {
use AssertKind::*;
use BinOp::*;
matches!(self, OverflowNeg(..) | Overflow(Add | Sub | Mul | Shl | Shr, ..))
}
/// Getting a description does not require `O` to be printable, and does not
/// require allocation.
/// The caller is expected to handle `BoundsCheck` and `MisalignedPointerDereference` separately.
pub fn description(&self) -> &'static str {
use AssertKind::*;
match self {
Overflow(BinOp::Add, _, _) => "attempt to add with overflow",
Overflow(BinOp::Sub, _, _) => "attempt to subtract with overflow",
Overflow(BinOp::Mul, _, _) => "attempt to multiply with overflow",
Overflow(BinOp::Div, _, _) => "attempt to divide with overflow",
Overflow(BinOp::Rem, _, _) => "attempt to calculate the remainder with overflow",
OverflowNeg(_) => "attempt to negate with overflow",
Overflow(BinOp::Shr, _, _) => "attempt to shift right with overflow",
Overflow(BinOp::Shl, _, _) => "attempt to shift left with overflow",
Overflow(op, _, _) => bug!("{:?} cannot overflow", op),
DivisionByZero(_) => "attempt to divide by zero",
RemainderByZero(_) => "attempt to calculate the remainder with a divisor of zero",
ResumedAfterReturn(GeneratorKind::Gen) => "generator resumed after completion",
ResumedAfterReturn(GeneratorKind::Async(_)) => "`async fn` resumed after completion",
ResumedAfterPanic(GeneratorKind::Gen) => "generator resumed after panicking",
ResumedAfterPanic(GeneratorKind::Async(_)) => "`async fn` resumed after panicking",
BoundsCheck { .. } | MisalignedPointerDereference { .. } => {
bug!("Unexpected AssertKind")
}
}
}
/// Format the message arguments for the `assert(cond, msg..)` terminator in MIR printing.
pub fn fmt_assert_args<W: Write>(&self, f: &mut W) -> fmt::Result
where
O: Debug,
{
use AssertKind::*;
match self {
BoundsCheck { ref len, ref index } => write!(
f,
"\"index out of bounds: the length is {{}} but the index is {{}}\", {:?}, {:?}",
len, index
),
OverflowNeg(op) => {
write!(f, "\"attempt to negate `{{}}`, which would overflow\", {:?}", op)
}
DivisionByZero(op) => write!(f, "\"attempt to divide `{{}}` by zero\", {:?}", op),
RemainderByZero(op) => write!(
f,
"\"attempt to calculate the remainder of `{{}}` with a divisor of zero\", {:?}",
op
),
Overflow(BinOp::Add, l, r) => write!(
f,
"\"attempt to compute `{{}} + {{}}`, which would overflow\", {:?}, {:?}",
l, r
),
Overflow(BinOp::Sub, l, r) => write!(
f,
"\"attempt to compute `{{}} - {{}}`, which would overflow\", {:?}, {:?}",
l, r
),
Overflow(BinOp::Mul, l, r) => write!(
f,
"\"attempt to compute `{{}} * {{}}`, which would overflow\", {:?}, {:?}",
l, r
),
Overflow(BinOp::Div, l, r) => write!(
f,
"\"attempt to compute `{{}} / {{}}`, which would overflow\", {:?}, {:?}",
l, r
),
Overflow(BinOp::Rem, l, r) => write!(
f,
"\"attempt to compute the remainder of `{{}} % {{}}`, which would overflow\", {:?}, {:?}",
l, r
),
Overflow(BinOp::Shr, _, r) => {
write!(f, "\"attempt to shift right by `{{}}`, which would overflow\", {:?}", r)
}
Overflow(BinOp::Shl, _, r) => {
write!(f, "\"attempt to shift left by `{{}}`, which would overflow\", {:?}", r)
}
MisalignedPointerDereference { required, found } => {
write!(
f,
"\"misaligned pointer dereference: address must be a multiple of {{}} but is {{}}\", {:?}, {:?}",
required, found
)
}
_ => write!(f, "\"{}\"", self.description()),
}
}
}
impl<O: fmt::Debug> fmt::Debug for AssertKind<O> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
use AssertKind::*;
match self {
BoundsCheck { ref len, ref index } => write!(
f,
"index out of bounds: the length is {:?} but the index is {:?}",
len, index
),
OverflowNeg(op) => write!(f, "attempt to negate `{:#?}`, which would overflow", op),
DivisionByZero(op) => write!(f, "attempt to divide `{:#?}` by zero", op),
RemainderByZero(op) => write!(
f,
"attempt to calculate the remainder of `{:#?}` with a divisor of zero",
op
),
Overflow(BinOp::Add, l, r) => {
write!(f, "attempt to compute `{:#?} + {:#?}`, which would overflow", l, r)
}
Overflow(BinOp::Sub, l, r) => {
write!(f, "attempt to compute `{:#?} - {:#?}`, which would overflow", l, r)
}
Overflow(BinOp::Mul, l, r) => {
write!(f, "attempt to compute `{:#?} * {:#?}`, which would overflow", l, r)
}
Overflow(BinOp::Div, l, r) => {
write!(f, "attempt to compute `{:#?} / {:#?}`, which would overflow", l, r)
}
Overflow(BinOp::Rem, l, r) => write!(
f,
"attempt to compute the remainder of `{:#?} % {:#?}`, which would overflow",
l, r
),
Overflow(BinOp::Shr, _, r) => {
write!(f, "attempt to shift right by `{:#?}`, which would overflow", r)
}
Overflow(BinOp::Shl, _, r) => {
write!(f, "attempt to shift left by `{:#?}`, which would overflow", r)
}
MisalignedPointerDereference { required, found } => {
write!(
f,
"misaligned pointer dereference: address must be a multiple of {:?} but is {:?}",
required, found
)
}
_ => write!(f, "{}", self.description()),
}
}
}
///////////////////////////////////////////////////////////////////////////
// Statements
/// A statement in a basic block, including information about its source code.
#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
pub struct Statement<'tcx> {
pub source_info: SourceInfo,
pub kind: StatementKind<'tcx>,
}
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.
#[must_use = "If you don't need the statement, use `make_nop` instead"]
pub fn replace_nop(&mut self) -> Self {
Statement {
source_info: self.source_info,
kind: mem::replace(&mut self.kind, StatementKind::Nop),
}
}
}
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(box (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)
}
Deinit(ref place) => write!(fmt, "Deinit({:?})", place),
PlaceMention(ref place) => {
write!(fmt, "PlaceMention({:?})", place)
}
AscribeUserType(box (ref place, ref c_ty), ref variance) => {
write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty)
}
Coverage(box self::Coverage { ref kind, code_region: Some(ref rgn) }) => {
write!(fmt, "Coverage::{:?} for {:?}", kind, rgn)
}
Coverage(box ref coverage) => write!(fmt, "Coverage::{:?}", coverage.kind),
Intrinsic(box ref intrinsic) => write!(fmt, "{intrinsic}"),
ConstEvalCounter => write!(fmt, "ConstEvalCounter"),
Nop => write!(fmt, "nop"),
}
}
}
impl<'tcx> StatementKind<'tcx> {
pub fn as_assign_mut(&mut self) -> Option<&mut (Place<'tcx>, Rvalue<'tcx>)> {
match self {
StatementKind::Assign(x) => Some(x),
_ => None,
}
}
pub fn as_assign(&self) -> Option<&(Place<'tcx>, Rvalue<'tcx>)> {
match self {
StatementKind::Assign(x) => Some(x),
_ => None,
}
}
}
///////////////////////////////////////////////////////////////////////////
// Places
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::OpaqueCast(_)
| Self::ConstantIndex { .. }
| Self::Subslice { .. }
| Self::Downcast(_, _) => false,
}
}
/// Returns `true` if the target of this projection always refers to the same memory region
/// whatever the state of the program.
pub fn is_stable_offset(&self) -> bool {
match self {
Self::Deref | Self::Index(_) => false,
Self::Field(_, _)
| Self::OpaqueCast(_)
| Self::ConstantIndex { .. }
| Self::Subslice { .. }
| Self::Downcast(_, _) => true,
}
}
/// Returns `true` if this is a `Downcast` projection with the given `VariantIdx`.
pub fn is_downcast_to(&self, v: VariantIdx) -> bool {
matches!(*self, Self::Downcast(_, x) if x == v)
}
/// Returns `true` if this is a `Field` projection with the given index.
pub fn is_field_to(&self, f: FieldIdx) -> bool {
matches!(*self, Self::Field(x, _) if x == f)
}
/// Returns `true` if this is accepted inside `VarDebugInfoContents::Place`.
pub fn can_use_in_debuginfo(&self) -> bool {
match self {
Self::ConstantIndex { from_end: false, .. }
| Self::Deref
| Self::Downcast(_, _)
| Self::Field(_, _) => true,
Self::ConstantIndex { from_end: true, .. }
| Self::Index(_)
| Self::OpaqueCast(_)
| Self::Subslice { .. } => false,
}
}
}
/// 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<(), ()>;
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct PlaceRef<'tcx> {
pub local: Local,
pub projection: &'tcx [PlaceElem<'tcx>],
}
// Once we stop implementing `Ord` for `DefId`,
// this impl will be unnecessary. Until then, we'll
// leave this impl in place to prevent re-adding a
// dependency on the `Ord` impl for `DefId`
impl<'tcx> !PartialOrd for PlaceRef<'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 { 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())
}
/// If MirPhase >= Derefered and if projection contains Deref,
/// It's guaranteed to be in the first place
pub fn has_deref(&self) -> bool {
// To make sure this is not accidentally used in wrong mir phase
debug_assert!(
self.projection.is_empty() || !self.projection[1..].contains(&PlaceElem::Deref)
);
self.projection.first() == Some(&PlaceElem::Deref)
}
/// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
/// a single deref of a local.
#[inline(always)]
pub fn local_or_deref_local(&self) -> Option<Local> {
self.as_ref().local_or_deref_local()
}
/// If this place represents a local variable like `_X` with no
/// projections, return `Some(_X)`.
#[inline(always)]
pub fn as_local(&self) -> Option<Local> {
self.as_ref().as_local()
}
#[inline]
pub fn as_ref(&self) -> PlaceRef<'tcx> {
PlaceRef { local: self.local, projection: &self.projection }
}
/// Iterate over the projections in evaluation order, i.e., the first element is the base with
/// its projection and then subsequently more projections are added.
/// As a concrete example, given the place a.b.c, this would yield:
/// - (a, .b)
/// - (a.b, .c)
///
/// Given a place without projections, the iterator is empty.
#[inline]
pub fn iter_projections(
self,
) -> impl Iterator<Item = (PlaceRef<'tcx>, PlaceElem<'tcx>)> + DoubleEndedIterator {
self.as_ref().iter_projections()
}
/// Generates a new place by appending `more_projections` to the existing ones
/// and interning the result.
pub fn project_deeper(self, more_projections: &[PlaceElem<'tcx>], tcx: TyCtxt<'tcx>) -> Self {
if more_projections.is_empty() {
return self;
}
self.as_ref().project_deeper(more_projections, tcx)
}
}
impl From<Local> for Place<'_> {
#[inline]
fn from(local: Local) -> Self {
Place { local, projection: List::empty() }
}
}
impl<'tcx> PlaceRef<'tcx> {
/// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
/// a single deref of a local.
pub fn local_or_deref_local(&self) -> Option<Local> {
match *self {
PlaceRef { local, projection: [] }
| PlaceRef { local, projection: [ProjectionElem::Deref] } => Some(local),
_ => None,
}
}
/// 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())
}
/// If MirPhase >= Derefered and if projection contains Deref,
/// It's guaranteed to be in the first place
pub fn has_deref(&self) -> bool {
self.projection.first() == Some(&PlaceElem::Deref)
}
/// If this place represents a local variable like `_X` with no
/// projections, return `Some(_X)`.
#[inline]
pub fn as_local(&self) -> Option<Local> {
match *self {
PlaceRef { local, projection: [] } => Some(local),
_ => None,
}
}
#[inline]
pub fn last_projection(&self) -> Option<(PlaceRef<'tcx>, PlaceElem<'tcx>)> {
if let &[ref proj_base @ .., elem] = self.projection {
Some((PlaceRef { local: self.local, projection: proj_base }, elem))
} else {
None
}
}
/// Iterate over the projections in evaluation order, i.e., the first element is the base with
/// its projection and then subsequently more projections are added.
/// As a concrete example, given the place a.b.c, this would yield:
/// - (a, .b)
/// - (a.b, .c)
///
/// Given a place without projections, the iterator is empty.
#[inline]
pub fn iter_projections(
self,
) -> impl Iterator<Item = (PlaceRef<'tcx>, PlaceElem<'tcx>)> + DoubleEndedIterator {
self.projection.iter().enumerate().map(move |(i, proj)| {
let base = PlaceRef { local: self.local, projection: &self.projection[..i] };
(base, *proj)
})
}
/// Generates a new place by appending `more_projections` to the existing ones
/// and interning the result.
pub fn project_deeper(
self,
more_projections: &[PlaceElem<'tcx>],
tcx: TyCtxt<'tcx>,
) -> Place<'tcx> {
let mut v: Vec<PlaceElem<'tcx>>;
let new_projections = if self.projection.is_empty() {
more_projections
} else {
v = Vec::with_capacity(self.projection.len() + more_projections.len());
v.extend(self.projection);
v.extend(more_projections);
&v
};
Place { local: self.local, projection: tcx.mk_place_elems(new_projections) }
}
}
impl Debug for Place<'_> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
for elem in self.projection.iter().rev() {
match elem {
ProjectionElem::OpaqueCast(_)
| ProjectionElem::Downcast(_, _)
| ProjectionElem::Field(_, _) => {
write!(fmt, "(").unwrap();
}
ProjectionElem::Deref => {
write!(fmt, "(*").unwrap();
}
ProjectionElem::Index(_)
| ProjectionElem::ConstantIndex { .. }
| ProjectionElem::Subslice { .. } => {}
}
}
write!(fmt, "{:?}", self.local)?;
for elem in self.projection.iter() {
match elem {
ProjectionElem::OpaqueCast(ty) => {
write!(fmt, " as {})", ty)?;
}
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, from_end: true } if to == 0 => {
write!(fmt, "[{:?}:]", from)?;
}
ProjectionElem::Subslice { from, to, from_end: true } if from == 0 => {
write!(fmt, "[:-{:?}]", to)?;
}
ProjectionElem::Subslice { from, to, from_end: true } => {
write!(fmt, "[{:?}:-{:?}]", from, to)?;
}
ProjectionElem::Subslice { from, to, from_end: false } => {
write!(fmt, "[{:?}..{:?}]", from, to)?;
}
}
}
Ok(())
}
}
///////////////////////////////////////////////////////////////////////////
// Scopes
rustc_index::newtype_index! {
#[derive(HashStable)]
#[debug_format = "scope[{}]"]
pub struct SourceScope {
const OUTERMOST_SOURCE_SCOPE = 0;
}
}
impl SourceScope {
/// Finds the original HirId this MIR item came from.
/// This is necessary after MIR optimizations, as otherwise we get a HirId
/// from the function that was inlined instead of the function call site.
pub fn lint_root(
self,
source_scopes: &IndexSlice<SourceScope, SourceScopeData<'_>>,
) -> Option<HirId> {
let mut data = &source_scopes[self];
// FIXME(oli-obk): we should be able to just walk the `inlined_parent_scope`, but it
// does not work as I thought it would. Needs more investigation and documentation.
while data.inlined.is_some() {
trace!(?data);
data = &source_scopes[data.parent_scope.unwrap()];
}
trace!(?data);
match &data.local_data {
ClearCrossCrate::Set(data) => Some(data.lint_root),
ClearCrossCrate::Clear => None,
}
}
/// The instance this source scope was inlined from, if any.
#[inline]
pub fn inlined_instance<'tcx>(
self,
source_scopes: &IndexSlice<SourceScope, SourceScopeData<'tcx>>,
) -> Option<ty::Instance<'tcx>> {
let scope_data = &source_scopes[self];
if let Some((inlined_instance, _)) = scope_data.inlined {
Some(inlined_instance)
} else if let Some(inlined_scope) = scope_data.inlined_parent_scope {
Some(source_scopes[inlined_scope].inlined.unwrap().0)
} else {
None
}
}
}
#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
pub struct SourceScopeData<'tcx> {
pub span: Span,
pub parent_scope: Option<SourceScope>,
/// Whether this scope is the root of a scope tree of another body,
/// inlined into this body by the MIR inliner.
/// `ty::Instance` is the callee, and the `Span` is the call site.
pub inlined: Option<(ty::Instance<'tcx>, Span)>,
/// Nearest (transitive) parent scope (if any) which is inlined.
/// This is an optimization over walking up `parent_scope`
/// until a scope with `inlined: Some(...)` is found.
pub inlined_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, TyEncodable, TyDecodable, 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
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: impl IntoIterator<Item = GenericArg<'tcx>>,
span: Span,
) -> Self {
let ty = tcx.mk_fn_def(def_id, substs);
Operand::Constant(Box::new(Constant {
span,
user_ty: None,
literal: ConstantKind::Val(ConstValue::ZeroSized, ty),
}))
}
pub fn is_move(&self) -> bool {
matches!(self, Operand::Move(..))
}
/// Convenience helper to make a literal-like constant from a given scalar value.
/// Since this is used to synthesize MIR, assumes `user_ty` is None.
pub fn const_from_scalar(
tcx: TyCtxt<'tcx>,
ty: Ty<'tcx>,
val: Scalar,
span: Span,
) -> Operand<'tcx> {
debug_assert!({
let param_env_and_ty = ty::ParamEnv::empty().and(ty);
let type_size = tcx
.layout_of(param_env_and_ty)
.unwrap_or_else(|e| panic!("could not compute layout for {:?}: {:?}", ty, e))
.size;
let scalar_size = match val {
Scalar::Int(int) => int.size(),
_ => panic!("Invalid scalar type {:?}", val),
};
scalar_size == type_size
});
Operand::Constant(Box::new(Constant {
span,
user_ty: None,
literal: ConstantKind::Val(ConstValue::Scalar(val), ty),
}))
}
pub fn to_copy(&self) -> Self {
match *self {
Operand::Copy(_) | Operand::Constant(_) => self.clone(),
Operand::Move(place) => Operand::Copy(place),
}
}
/// Returns the `Place` that is the target of this `Operand`, or `None` if this `Operand` is a
/// constant.
pub fn place(&self) -> Option<Place<'tcx>> {
match self {
Operand::Copy(place) | Operand::Move(place) => Some(*place),
Operand::Constant(_) => None,
}
}
/// Returns the `Constant` that is the target of this `Operand`, or `None` if this `Operand` is a
/// place.
pub fn constant(&self) -> Option<&Constant<'tcx>> {
match self {
Operand::Constant(x) => Some(&**x),
Operand::Copy(_) | Operand::Move(_) => None,
}
}
/// Gets the `ty::FnDef` from an operand if it's a constant function item.
///
/// While this is unlikely in general, it's the normal case of what you'll
/// find as the `func` in a [`TerminatorKind::Call`].
pub fn const_fn_def(&self) -> Option<(DefId, SubstsRef<'tcx>)> {
let const_ty = self.constant()?.literal.ty();
if let ty::FnDef(def_id, substs) = *const_ty.kind() { Some((def_id, substs)) } else { None }
}
}
///////////////////////////////////////////////////////////////////////////
/// Rvalues
impl<'tcx> Rvalue<'tcx> {
/// Returns true if rvalue can be safely removed when the result is unused.
#[inline]
pub fn is_safe_to_remove(&self) -> bool {
match self {
// Pointer to int casts may be side-effects due to exposing the provenance.
// While the model is undecided, we should be conservative. See
// <https://www.ralfj.de/blog/2022/04/11/provenance-exposed.html>
Rvalue::Cast(CastKind::PointerExposeAddress, _, _) => false,
Rvalue::Use(_)
| Rvalue::CopyForDeref(_)
| Rvalue::Repeat(_, _)
| Rvalue::Ref(_, _, _)
| Rvalue::ThreadLocalRef(_)
| Rvalue::AddressOf(_, _)
| Rvalue::Len(_)
| Rvalue::Cast(
CastKind::IntToInt
| CastKind::FloatToInt
| CastKind::FloatToFloat
| CastKind::IntToFloat
| CastKind::FnPtrToPtr
| CastKind::PtrToPtr
| CastKind::Pointer(_)
| CastKind::PointerFromExposedAddress
| CastKind::DynStar
| CastKind::Transmute,
_,
_,
)
| Rvalue::BinaryOp(_, _)
| Rvalue::CheckedBinaryOp(_, _)
| Rvalue::NullaryOp(_, _)
| Rvalue::UnaryOp(_, _)
| Rvalue::Discriminant(_)
| Rvalue::Aggregate(_, _)
| Rvalue::ShallowInitBox(_, _) => true,
}
}
}
impl BorrowKind {
pub fn mutability(&self) -> Mutability {
match *self {
BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => Mutability::Not,
BorrowKind::Mut { .. } => Mutability::Mut,
}
}
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,
}
}
// FIXME: won't be used after diagnostic migration
pub fn describe_mutability(&self) -> &str {
match *self {
BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => "immutable",
BorrowKind::Mut { .. } => "mutable",
}
}
}
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, b) => {
write!(fmt, "[{:?}; ", a)?;
pretty_print_const(b, fmt, false)?;
write!(fmt, "]")
}
Len(ref a) => write!(fmt, "Len({:?})", a),
Cast(ref kind, ref place, ref ty) => {
write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind)
}
BinaryOp(ref op, box (ref a, ref b)) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
CheckedBinaryOp(ref op, box (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) => match op {
NullOp::SizeOf => write!(fmt, "SizeOf({:?})", t),
NullOp::AlignOf => write!(fmt, "AlignOf({:?})", t),
NullOp::OffsetOf(fields) => write!(fmt, "OffsetOf({:?}, {:?})", t, fields),
},
ThreadLocalRef(did) => ty::tls::with(|tcx| {
let muta = tcx.static_mutability(did).unwrap().prefix_str();
write!(fmt, "&/*tls*/ {}{}", muta, tcx.def_path_str(did))
}),
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.unstable_opts.identify_regions
});
let region = if print_region {
let mut region = region.to_string();
if !region.is_empty() {
region.push(' ');
}
region
} else {
// Do not even print 'static
String::new()
};
write!(fmt, "&{}{}{:?}", region, kind_str, place)
}
CopyForDeref(ref place) => write!(fmt, "deref_copy {:#?}", place),
AddressOf(mutability, ref place) => {
let kind_str = match mutability {
Mutability::Mut => "mut",
Mutability::Not => "const",
};
write!(fmt, "&raw {} {:?}", kind_str, place)
}
Aggregate(ref kind, ref places) => {
let fmt_tuple = |fmt: &mut Formatter<'_>, name: &str| {
let mut tuple_fmt = fmt.debug_tuple(name);
for place in places {
tuple_fmt.field(place);
}
tuple_fmt.finish()
};
match **kind {
AggregateKind::Array(_) => write!(fmt, "{:?}", places),
AggregateKind::Tuple => {
if places.is_empty() {
write!(fmt, "()")
} else {
fmt_tuple(fmt, "")
}
}
AggregateKind::Adt(adt_did, variant, substs, _user_ty, _) => {
ty::tls::with(|tcx| {
let variant_def = &tcx.adt_def(adt_did).variant(variant);
let substs = tcx.lift(substs).expect("could not lift for printing");
let name = FmtPrinter::new(tcx, Namespace::ValueNS)
.print_def_path(variant_def.def_id, substs)?
.into_buffer();
match variant_def.ctor_kind() {
Some(CtorKind::Const) => fmt.write_str(&name),
Some(CtorKind::Fn) => fmt_tuple(fmt, &name),
None => {
let mut struct_fmt = fmt.debug_struct(&name);
for (field, place) in iter::zip(&variant_def.fields, places) {
struct_fmt.field(field.name.as_str(), place);
}
struct_fmt.finish()
}
}
})
}
AggregateKind::Closure(def_id, substs) => ty::tls::with(|tcx| {
let name = if tcx.sess.opts.unstable_opts.span_free_formats {
let substs = tcx.lift(substs).unwrap();
format!("[closure@{}]", tcx.def_path_str_with_substs(def_id, substs),)
} else {
let span = tcx.def_span(def_id);
format!(
"[closure@{}]",
tcx.sess.source_map().span_to_diagnostic_string(span)
)
};
let mut struct_fmt = fmt.debug_struct(&name);
// FIXME(project-rfc-2229#48): This should be a list of capture names/places
if let Some(def_id) = def_id.as_local()
&& let Some(upvars) = tcx.upvars_mentioned(def_id)
{
for (&var_id, place) in iter::zip(upvars.keys(), places) {
let var_name = tcx.hir().name(var_id);
struct_fmt.field(var_name.as_str(), place);
}
} else {
for (index, place) in places.iter().enumerate() {
struct_fmt.field(&format!("{index}"), place);
}
}
struct_fmt.finish()
}),
AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
let name = format!("[generator@{:?}]", tcx.def_span(def_id));
let mut struct_fmt = fmt.debug_struct(&name);
// FIXME(project-rfc-2229#48): This should be a list of capture names/places
if let Some(def_id) = def_id.as_local()
&& let Some(upvars) = tcx.upvars_mentioned(def_id)
{
for (&var_id, place) in iter::zip(upvars.keys(), places) {
let var_name = tcx.hir().name(var_id);
struct_fmt.field(var_name.as_str(), place);
}
} else {
for (index, place) in places.iter().enumerate() {
struct_fmt.field(&format!("{index}"), place);
}
}
struct_fmt.finish()
}),
}
}
ShallowInitBox(ref place, ref ty) => {
write!(fmt, "ShallowInitBox({:?}, {:?})", place, ty)
}
}
}
}
///////////////////////////////////////////////////////////////////////////
/// 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, Copy, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)]
#[derive(TypeFoldable, TypeVisitable)]
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: ConstantKind<'tcx>,
}
#[derive(Clone, Copy, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable, Debug)]
#[derive(Lift, TypeFoldable, TypeVisitable)]
pub enum ConstantKind<'tcx> {
/// This constant came from the type system
Ty(ty::Const<'tcx>),
/// An unevaluated mir constant which is not part of the type system.
Unevaluated(UnevaluatedConst<'tcx>, Ty<'tcx>),
/// This constant cannot go back into the type system, as it represents
/// something the type system cannot handle (e.g. pointers).
Val(interpret::ConstValue<'tcx>, Ty<'tcx>),
}
impl<'tcx> Constant<'tcx> {
pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option<DefId> {
match self.literal.try_to_scalar() {
Some(Scalar::Ptr(ptr, _size)) => match tcx.global_alloc(ptr.provenance) {
GlobalAlloc::Static(def_id) => {
assert!(!tcx.is_thread_local_static(def_id));
Some(def_id)
}
_ => None,
},
_ => None,
}
}
#[inline]
pub fn ty(&self) -> Ty<'tcx> {
self.literal.ty()
}
}
impl<'tcx> ConstantKind<'tcx> {
#[inline(always)]
pub fn ty(&self) -> Ty<'tcx> {
match self {
ConstantKind::Ty(c) => c.ty(),
ConstantKind::Val(_, ty) | ConstantKind::Unevaluated(_, ty) => *ty,
}
}
#[inline]
pub fn try_to_value(self, tcx: TyCtxt<'tcx>) -> Option<interpret::ConstValue<'tcx>> {
match self {
ConstantKind::Ty(c) => match c.kind() {
ty::ConstKind::Value(valtree) => Some(tcx.valtree_to_const_val((c.ty(), valtree))),
_ => None,
},
ConstantKind::Val(val, _) => Some(val),
ConstantKind::Unevaluated(..) => None,
}
}
#[inline]
pub fn try_to_scalar(self) -> Option<Scalar> {
match self {
ConstantKind::Ty(c) => match c.kind() {
ty::ConstKind::Value(valtree) => match valtree {
ty::ValTree::Leaf(scalar_int) => Some(Scalar::Int(scalar_int)),
ty::ValTree::Branch(_) => None,
},
_ => None,
},
ConstantKind::Val(val, _) => val.try_to_scalar(),
ConstantKind::Unevaluated(..) => None,
}
}
#[inline]
pub fn try_to_scalar_int(self) -> Option<ScalarInt> {
Some(self.try_to_scalar()?.assert_int())
}
#[inline]
pub fn try_to_bits(self, size: Size) -> Option<u128> {
self.try_to_scalar_int()?.to_bits(size).ok()
}
#[inline]
pub fn try_to_bool(self) -> Option<bool> {
self.try_to_scalar_int()?.try_into().ok()
}
#[inline]
pub fn eval(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self {
match self {
Self::Ty(c) => {
if let Some(val) = c.kind().try_eval_for_mir(tcx, param_env) {
match val {
Ok(val) => Self::Val(val, c.ty()),
Err(guar) => Self::Ty(tcx.const_error(self.ty(), guar)),
}
} else {
self
}
}
Self::Val(_, _) => self,
Self::Unevaluated(uneval, ty) => {
// FIXME: We might want to have a `try_eval`-like function on `Unevaluated`
match tcx.const_eval_resolve(param_env, uneval, None) {
Ok(val) => Self::Val(val, ty),
Err(ErrorHandled::TooGeneric) => self,
Err(ErrorHandled::Reported(guar)) => Self::Ty(tcx.const_error(ty, guar.into())),
}
}
}
}
/// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type.
#[inline]
pub fn eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 {
self.try_eval_bits(tcx, param_env, ty)
.unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self))
}
#[inline]
pub fn try_eval_bits(
&self,
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
ty: Ty<'tcx>,
) -> Option<u128> {
match self {
Self::Ty(ct) => ct.try_eval_bits(tcx, param_env, ty),
Self::Val(val, t) => {
assert_eq!(*t, ty);
let size =
tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size;
val.try_to_bits(size)
}
Self::Unevaluated(uneval, ty) => {
match tcx.const_eval_resolve(param_env, *uneval, None) {
Ok(val) => {
let size = tcx
.layout_of(param_env.with_reveal_all_normalized(tcx).and(*ty))
.ok()?
.size;
val.try_to_bits(size)
}
Err(_) => None,
}
}
}
}
#[inline]
pub fn try_eval_bool(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Option<bool> {
match self {
Self::Ty(ct) => ct.try_eval_bool(tcx, param_env),
Self::Val(val, _) => val.try_to_bool(),
Self::Unevaluated(uneval, _) => {
match tcx.const_eval_resolve(param_env, *uneval, None) {
Ok(val) => val.try_to_bool(),
Err(_) => None,
}
}
}
}
#[inline]
pub fn try_eval_target_usize(
&self,
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
) -> Option<u64> {
match self {
Self::Ty(ct) => ct.try_eval_target_usize(tcx, param_env),
Self::Val(val, _) => val.try_to_target_usize(tcx),
Self::Unevaluated(uneval, _) => {
match tcx.const_eval_resolve(param_env, *uneval, None) {
Ok(val) => val.try_to_target_usize(tcx),
Err(_) => None,
}
}
}
}
#[inline]
pub fn from_value(val: ConstValue<'tcx>, ty: Ty<'tcx>) -> Self {
Self::Val(val, ty)
}
pub fn from_bits(
tcx: TyCtxt<'tcx>,
bits: u128,
param_env_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
) -> Self {
let size = tcx
.layout_of(param_env_ty)
.unwrap_or_else(|e| {
bug!("could not compute layout for {:?}: {:?}", param_env_ty.value, e)
})
.size;
let cv = ConstValue::Scalar(Scalar::from_uint(bits, size));
Self::Val(cv, param_env_ty.value)
}
#[inline]
pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> Self {
let cv = ConstValue::from_bool(v);
Self::Val(cv, tcx.types.bool)
}
#[inline]
pub fn zero_sized(ty: Ty<'tcx>) -> Self {
let cv = ConstValue::ZeroSized;
Self::Val(cv, ty)
}
pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self {
let ty = tcx.types.usize;
Self::from_bits(tcx, n as u128, ty::ParamEnv::empty().and(ty))
}
#[inline]
pub fn from_scalar(_tcx: TyCtxt<'tcx>, s: Scalar, ty: Ty<'tcx>) -> Self {
let val = ConstValue::Scalar(s);
Self::Val(val, ty)
}
#[instrument(skip(tcx), level = "debug", ret)]
pub fn from_inline_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
let body_id = match tcx.hir().get(hir_id) {
hir::Node::AnonConst(ac) => ac.body,
_ => span_bug!(
tcx.def_span(def_id.to_def_id()),
"from_inline_const can only process anonymous constants"
),
};
let expr = &tcx.hir().body(body_id).value;
let ty = tcx.typeck(def_id).node_type(hir_id);
let lit_input = match expr.kind {
hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => match expr.kind {
hir::ExprKind::Lit(ref lit) => {
Some(LitToConstInput { lit: &lit.node, ty, neg: true })
}
_ => None,
},
_ => None,
};
if let Some(lit_input) = lit_input {
// If an error occurred, ignore that it's a literal and leave reporting the error up to
// mir.
match tcx.at(expr.span).lit_to_mir_constant(lit_input) {
Ok(c) => return c,
Err(_) => {}
}
}
let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id());
let parent_substs =
tcx.erase_regions(InternalSubsts::identity_for_item(tcx, typeck_root_def_id));
let substs =
ty::InlineConstSubsts::new(tcx, ty::InlineConstSubstsParts { parent_substs, ty })
.substs;
let uneval = UnevaluatedConst { def: def_id.to_def_id(), substs, promoted: None };
debug_assert!(!uneval.has_free_regions());
Self::Unevaluated(uneval, ty)
}
/// Literals are converted to `ConstantKindVal`, const generic parameters are eagerly
/// converted to a constant, everything else becomes `Unevaluated`.
#[instrument(skip(tcx), level = "debug", ret)]
pub fn from_anon_const(
tcx: TyCtxt<'tcx>,
def: LocalDefId,
param_env: ty::ParamEnv<'tcx>,
) -> Self {
let body_id = match tcx.hir().get_by_def_id(def) {
hir::Node::AnonConst(ac) => ac.body,
_ => {
span_bug!(tcx.def_span(def), "from_anon_const can only process anonymous constants")
}
};
let expr = &tcx.hir().body(body_id).value;
debug!(?expr);
// Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments
// currently have to be wrapped in curly brackets, so it's necessary to special-case.
let expr = match &expr.kind {
hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => {
block.expr.as_ref().unwrap()
}
_ => expr,
};
debug!("expr.kind: {:?}", expr.kind);
let ty = tcx.type_of(def).subst_identity();
debug!(?ty);
// FIXME(const_generics): We currently have to special case parameters because `min_const_generics`
// does not provide the parents generics to anonymous constants. We still allow generic const
// parameters by themselves however, e.g. `N`. These constants would cause an ICE if we were to
// ever try to substitute the generic parameters in their bodies.
//
// While this doesn't happen as these constants are always used as `ty::ConstKind::Param`, it does
// cause issues if we were to remove that special-case and try to evaluate the constant instead.
use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath};
match expr.kind {
ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => {
// Find the name and index of the const parameter by indexing the generics of
// the parent item and construct a `ParamConst`.
let item_def_id = tcx.parent(def_id);
let generics = tcx.generics_of(item_def_id);
let index = generics.param_def_id_to_index[&def_id];
let name = tcx.item_name(def_id);
let ty_const = tcx.mk_const(ty::ParamConst::new(index, name), ty);
debug!(?ty_const);
return Self::Ty(ty_const);
}
_ => {}
}
let hir_id = tcx.hir().local_def_id_to_hir_id(def);
let parent_substs = if let Some(parent_hir_id) = tcx.hir().opt_parent_id(hir_id)
&& let Some(parent_did) = parent_hir_id.as_owner()
{
InternalSubsts::identity_for_item(tcx, parent_did)
} else {
List::empty()
};
debug!(?parent_substs);
let did = def.to_def_id();
let child_substs = InternalSubsts::identity_for_item(tcx, did);
let substs =
tcx.mk_substs_from_iter(parent_substs.into_iter().chain(child_substs.into_iter()));
debug!(?substs);
let span = tcx.def_span(def);
let uneval = UnevaluatedConst::new(did, substs);
debug!(?span, ?param_env);
match tcx.const_eval_resolve(param_env, uneval, Some(span)) {
Ok(val) => {
debug!("evaluated const value");
Self::Val(val, ty)
}
Err(_) => {
debug!("error encountered during evaluation");
// Error was handled in `const_eval_resolve`. Here we just create a
// new unevaluated const and error hard later in codegen
Self::Unevaluated(
UnevaluatedConst {
def: did,
substs: InternalSubsts::identity_for_item(tcx, did),
promoted: None,
},
ty,
)
}
}
}
pub fn from_const(c: ty::Const<'tcx>, tcx: TyCtxt<'tcx>) -> Self {
match c.kind() {
ty::ConstKind::Value(valtree) => {
let const_val = tcx.valtree_to_const_val((c.ty(), valtree));
Self::Val(const_val, c.ty())
}
ty::ConstKind::Unevaluated(uv) => Self::Unevaluated(uv.expand(), c.ty()),
_ => Self::Ty(c),
}
}
}
/// An unevaluated (potentially generic) constant used in MIR.
#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Lift)]
#[derive(Hash, HashStable, TypeFoldable, TypeVisitable)]
pub struct UnevaluatedConst<'tcx> {
pub def: DefId,
pub substs: SubstsRef<'tcx>,
pub promoted: Option<Promoted>,
}
impl<'tcx> UnevaluatedConst<'tcx> {
// FIXME: probably should get rid of this method. It's also wrong to
// shrink and then later expand a promoted.
#[inline]
pub fn shrink(self) -> ty::UnevaluatedConst<'tcx> {
ty::UnevaluatedConst { def: self.def, substs: self.substs }
}
}
impl<'tcx> UnevaluatedConst<'tcx> {
#[inline]
pub fn new(def: DefId, substs: SubstsRef<'tcx>) -> UnevaluatedConst<'tcx> {
UnevaluatedConst { def, substs, promoted: Default::default() }
}
}
/// 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:
///
/// ```ignore (illustrative)
/// 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, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
pub struct UserTypeProjections {
pub contents: Vec<(UserTypeProjection, Span)>,
}
impl<'tcx> UserTypeProjections {
pub fn none() -> Self {
UserTypeProjections { contents: vec![] }
}
pub fn is_empty(&self) -> bool {
self.contents.is_empty()
}
pub fn projections_and_spans(
&self,
) -> impl Iterator<Item = &(UserTypeProjection, Span)> + ExactSizeIterator {
self.contents.iter()
}
pub fn projections(&self) -> impl Iterator<Item = &UserTypeProjection> + ExactSizeIterator {
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.into_iter().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: u64, to: u64) -> 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: FieldIdx) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.leaf(field))
}
pub fn variant(
self,
adt_def: AdtDef<'tcx>,
variant_index: VariantIdx,
field_index: FieldIdx,
) -> Self {
self.map_projections(|pat_ty_proj| pat_ty_proj.variant(adt_def, variant_index, field_index))
}
}
/// 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 projections 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, TyEncodable, TyDecodable, Hash, HashStable, PartialEq)]
#[derive(TypeFoldable, TypeVisitable)]
pub struct UserTypeProjection {
pub base: UserTypeAnnotationIndex,
pub projs: Vec<ProjectionKind>,
}
impl UserTypeProjection {
pub(crate) fn index(mut self) -> Self {
self.projs.push(ProjectionElem::Index(()));
self
}
pub(crate) fn subslice(mut self, from: u64, to: u64) -> Self {
self.projs.push(ProjectionElem::Subslice { from, to, from_end: true });
self
}
pub(crate) fn deref(mut self) -> Self {
self.projs.push(ProjectionElem::Deref);
self
}
pub(crate) fn leaf(mut self, field: FieldIdx) -> Self {
self.projs.push(ProjectionElem::Field(field, ()));
self
}
pub(crate) fn variant(
mut self,
adt_def: AdtDef<'_>,
variant_index: VariantIdx,
field_index: FieldIdx,
) -> Self {
self.projs.push(ProjectionElem::Downcast(
Some(adt_def.variant(variant_index).name),
variant_index,
));
self.projs.push(ProjectionElem::Field(field_index, ()));
self
}
}
rustc_index::newtype_index! {
#[derive(HashStable)]
#[debug_format = "promoted[{}]"]
pub struct 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 {
match self.ty().kind() {
ty::FnDef(..) => {}
_ => write!(fmt, "const ")?,
}
Display::fmt(&self.literal, fmt)
}
}
impl<'tcx> Display for ConstantKind<'tcx> {
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
match *self {
ConstantKind::Ty(c) => pretty_print_const(c, fmt, true),
ConstantKind::Val(val, ty) => pretty_print_const_value(val, ty, fmt, true),
// FIXME(valtrees): Correctly print mir constants.
ConstantKind::Unevaluated(..) => {
fmt.write_str("_")?;
Ok(())
}
}
}
}
fn pretty_print_const<'tcx>(
c: ty::Const<'tcx>,
fmt: &mut Formatter<'_>,
print_types: bool,
) -> fmt::Result {
use crate::ty::print::PrettyPrinter;
ty::tls::with(|tcx| {
let literal = tcx.lift(c).unwrap();
let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
cx.print_alloc_ids = true;
let cx = cx.pretty_print_const(literal, print_types)?;
fmt.write_str(&cx.into_buffer())?;
Ok(())
})
}
fn pretty_print_byte_str(fmt: &mut Formatter<'_>, byte_str: &[u8]) -> fmt::Result {
write!(fmt, "b\"{}\"", byte_str.escape_ascii())
}
fn comma_sep<'tcx>(fmt: &mut Formatter<'_>, elems: Vec<ConstantKind<'tcx>>) -> fmt::Result {
let mut first = true;
for elem in elems {
if !first {
fmt.write_str(", ")?;
}
fmt.write_str(&format!("{}", elem))?;
first = false;
}
Ok(())
}
// FIXME: Move that into `mir/pretty.rs`.
fn pretty_print_const_value<'tcx>(
ct: ConstValue<'tcx>,
ty: Ty<'tcx>,
fmt: &mut Formatter<'_>,
print_ty: bool,
) -> fmt::Result {
use crate::ty::print::PrettyPrinter;
ty::tls::with(|tcx| {
let ct = tcx.lift(ct).unwrap();
let ty = tcx.lift(ty).unwrap();
if tcx.sess.verbose() {
fmt.write_str(&format!("ConstValue({:?}: {})", ct, ty))?;
return Ok(());
}
let u8_type = tcx.types.u8;
match (ct, ty.kind()) {
// Byte/string slices, printed as (byte) string literals.
(ConstValue::Slice { data, start, end }, ty::Ref(_, inner, _)) => {
match inner.kind() {
ty::Slice(t) => {
if *t == u8_type {
// The `inspect` here is okay since we checked the bounds, and `u8` carries
// no provenance (we have an active slice reference here). We don't use
// this result to affect interpreter execution.
let byte_str = data
.inner()
.inspect_with_uninit_and_ptr_outside_interpreter(start..end);
pretty_print_byte_str(fmt, byte_str)?;
return Ok(());
}
}
ty::Str => {
// The `inspect` here is okay since we checked the bounds, and `str` carries
// no provenance (we have an active `str` reference here). We don't use this
// result to affect interpreter execution.
let slice = data
.inner()
.inspect_with_uninit_and_ptr_outside_interpreter(start..end);
fmt.write_str(&format!("{:?}", String::from_utf8_lossy(slice)))?;
return Ok(());
}
_ => {}
}
}
(ConstValue::ByRef { alloc, offset }, ty::Array(t, n)) if *t == u8_type => {
let n = n.kind().try_to_bits(tcx.data_layout.pointer_size).unwrap();
// cast is ok because we already checked for pointer size (32 or 64 bit) above
let range = AllocRange { start: offset, size: Size::from_bytes(n) };
let byte_str = alloc.inner().get_bytes_strip_provenance(&tcx, range).unwrap();
fmt.write_str("*")?;
pretty_print_byte_str(fmt, byte_str)?;
return Ok(());
}
// Aggregates, printed as array/tuple/struct/variant construction syntax.
//
// NB: the `has_non_region_param` check ensures that we can use
// the `destructure_const` query with an empty `ty::ParamEnv` without
// introducing ICEs (e.g. via `layout_of`) from missing bounds.
// E.g. `transmute([0usize; 2]): (u8, *mut T)` needs to know `T: Sized`
// to be able to destructure the tuple into `(0u8, *mut T)`
//
// FIXME(eddyb) for `--emit=mir`/`-Z dump-mir`, we should provide the
// correct `ty::ParamEnv` to allow printing *all* constant values.
(_, ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) if !ty.has_non_region_param() => {
let ct = tcx.lift(ct).unwrap();
let ty = tcx.lift(ty).unwrap();
if let Some(contents) = tcx.try_destructure_mir_constant(
ty::ParamEnv::reveal_all().and(ConstantKind::Val(ct, ty)),
) {
let fields = contents.fields.to_vec();
match *ty.kind() {
ty::Array(..) => {
fmt.write_str("[")?;
comma_sep(fmt, fields)?;
fmt.write_str("]")?;
}
ty::Tuple(..) => {
fmt.write_str("(")?;
comma_sep(fmt, fields)?;
if contents.fields.len() == 1 {
fmt.write_str(",")?;
}
fmt.write_str(")")?;
}
ty::Adt(def, _) if def.variants().is_empty() => {
fmt.write_str(&format!("{{unreachable(): {}}}", ty))?;
}
ty::Adt(def, substs) => {
let variant_idx = contents
.variant
.expect("destructed mir constant of adt without variant idx");
let variant_def = &def.variant(variant_idx);
let substs = tcx.lift(substs).unwrap();
let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
cx.print_alloc_ids = true;
let cx = cx.print_value_path(variant_def.def_id, substs)?;
fmt.write_str(&cx.into_buffer())?;
match variant_def.ctor_kind() {
Some(CtorKind::Const) => {}
Some(CtorKind::Fn) => {
fmt.write_str("(")?;
comma_sep(fmt, fields)?;
fmt.write_str(")")?;
}
None => {
fmt.write_str(" {{ ")?;
let mut first = true;
for (field_def, field) in iter::zip(&variant_def.fields, fields)
{
if !first {
fmt.write_str(", ")?;
}
fmt.write_str(&format!("{}: {}", field_def.name, field))?;
first = false;
}
fmt.write_str(" }}")?;
}
}
}
_ => unreachable!(),
}
return Ok(());
} else {
// Fall back to debug pretty printing for invalid constants.
fmt.write_str(&format!("{:?}", ct))?;
if print_ty {
fmt.write_str(&format!(": {}", ty))?;
}
return Ok(());
};
}
(ConstValue::Scalar(scalar), _) => {
let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
cx.print_alloc_ids = true;
let ty = tcx.lift(ty).unwrap();
cx = cx.pretty_print_const_scalar(scalar, ty, print_ty)?;
fmt.write_str(&cx.into_buffer())?;
return Ok(());
}
(ConstValue::ZeroSized, ty::FnDef(d, s)) => {
let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
cx.print_alloc_ids = true;
let cx = cx.print_value_path(*d, s)?;
fmt.write_str(&cx.into_buffer())?;
return Ok(());
}
// FIXME(oli-obk): also pretty print arrays and other aggregate constants by reading
// their fields instead of just dumping the memory.
_ => {}
}
// fallback
fmt.write_str(&format!("{:?}", ct))?;
if print_ty {
fmt.write_str(&format!(": {}", ty))?;
}
Ok(())
})
}
/// `Location` represents the position of the start of the statement; or, if
/// `statement_index` equals the number of statements, then the start of the
/// terminator.
#[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd, HashStable)]
pub struct Location {
/// The block that the location is within.
pub block: BasicBlock,
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: &Body<'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;
}
let predecessors = body.basic_blocks.predecessors();
// If we're in another block, then we want to check that block is a predecessor of `other`.
let mut queue: Vec<BasicBlock> = predecessors[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 its predecessors.
if visited.insert(block) {
queue.extend(predecessors[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.dominates(self.block, other.block)
}
}
}
// Some nodes are used a lot. Make sure they don't unintentionally get bigger.
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
mod size_asserts {
use super::*;
use rustc_data_structures::static_assert_size;
// tidy-alphabetical-start
static_assert_size!(BasicBlockData<'_>, 136);
static_assert_size!(LocalDecl<'_>, 40);
static_assert_size!(SourceScopeData<'_>, 72);
static_assert_size!(Statement<'_>, 32);
static_assert_size!(StatementKind<'_>, 16);
static_assert_size!(Terminator<'_>, 104);
static_assert_size!(TerminatorKind<'_>, 88);
static_assert_size!(VarDebugInfo<'_>, 80);
// tidy-alphabetical-end
}