2860 lines
101 KiB
Rust
2860 lines
101 KiB
Rust
//! MIR datatypes and passes. See the [rustc dev guide] for more info.
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//!
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//! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/mir/index.html
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use crate::mir::coverage::{CodeRegion, CoverageKind};
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use crate::mir::interpret::{Allocation, GlobalAlloc, Scalar};
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use crate::mir::visit::MirVisitable;
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use crate::ty::adjustment::PointerCast;
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use crate::ty::codec::{TyDecoder, TyEncoder};
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use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
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use crate::ty::print::{FmtPrinter, Printer};
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use crate::ty::subst::{Subst, SubstsRef};
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use crate::ty::{self, List, Ty, TyCtxt};
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use crate::ty::{AdtDef, InstanceDef, Region, ScalarInt, UserTypeAnnotationIndex};
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use rustc_hir as hir;
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use rustc_hir::def::{CtorKind, Namespace};
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use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
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use rustc_hir::{self, GeneratorKind};
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use rustc_target::abi::{Size, VariantIdx};
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use polonius_engine::Atom;
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pub use rustc_ast::Mutability;
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use rustc_data_structures::fx::FxHashSet;
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use rustc_data_structures::graph::dominators::{dominators, Dominators};
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use rustc_data_structures::graph::{self, GraphSuccessors};
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use rustc_index::bit_set::BitMatrix;
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use rustc_index::vec::{Idx, IndexVec};
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use rustc_serialize::{Decodable, Encodable};
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use rustc_span::symbol::Symbol;
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use rustc_span::{Span, DUMMY_SP};
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use rustc_target::asm::InlineAsmRegOrRegClass;
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use std::borrow::Cow;
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use std::convert::TryInto;
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use std::fmt::{self, Debug, Display, Formatter, Write};
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use std::ops::{ControlFlow, Index, IndexMut};
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use std::slice;
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use std::{iter, mem, option};
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use self::graph_cyclic_cache::GraphIsCyclicCache;
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use self::predecessors::{PredecessorCache, Predecessors};
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pub use self::query::*;
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pub mod abstract_const;
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pub mod coverage;
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mod graph_cyclic_cache;
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pub mod interpret;
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pub mod mono;
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mod predecessors;
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mod query;
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pub mod tcx;
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pub mod terminator;
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pub use terminator::*;
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pub mod traversal;
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mod type_foldable;
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pub mod visit;
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/// Types for locals
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pub type LocalDecls<'tcx> = IndexVec<Local, LocalDecl<'tcx>>;
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pub trait HasLocalDecls<'tcx> {
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fn local_decls(&self) -> &LocalDecls<'tcx>;
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}
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impl<'tcx> HasLocalDecls<'tcx> for LocalDecls<'tcx> {
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#[inline]
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fn local_decls(&self) -> &LocalDecls<'tcx> {
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self
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}
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}
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impl<'tcx> HasLocalDecls<'tcx> for Body<'tcx> {
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#[inline]
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fn local_decls(&self) -> &LocalDecls<'tcx> {
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&self.local_decls
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}
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}
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/// The various "big phases" that MIR goes through.
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///
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/// These phases all describe dialects of MIR. Since all MIR uses the same datastructures, the
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/// dialects forbid certain variants or values in certain phases.
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///
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/// Note: Each phase's validation checks all invariants of the *previous* phases' dialects. A phase
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/// that changes the dialect documents what invariants must be upheld *after* that phase finishes.
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///
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/// Warning: ordering of variants is significant.
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#[derive(Copy, Clone, TyEncodable, TyDecodable, Debug, PartialEq, Eq, PartialOrd, Ord)]
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#[derive(HashStable)]
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pub enum MirPhase {
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Build = 0,
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// FIXME(oli-obk): it's unclear whether we still need this phase (and its corresponding query).
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// We used to have this for pre-miri MIR based const eval.
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Const = 1,
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/// This phase checks the MIR for promotable elements and takes them out of the main MIR body
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/// by creating a new MIR body per promoted element. After this phase (and thus the termination
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/// of the `mir_promoted` query), these promoted elements are available in the `promoted_mir`
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/// query.
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ConstPromotion = 2,
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/// After this phase
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/// * the only `AggregateKind`s allowed are `Array` and `Generator`,
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/// * `DropAndReplace` is gone for good
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/// * `Drop` now uses explicit drop flags visible in the MIR and reaching a `Drop` terminator
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/// means that the auto-generated drop glue will be invoked.
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DropLowering = 3,
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/// After this phase, generators are explicit state machines (no more `Yield`).
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/// `AggregateKind::Generator` is gone for good.
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GeneratorLowering = 4,
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Optimization = 5,
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}
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impl MirPhase {
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/// Gets the index of the current MirPhase within the set of all `MirPhase`s.
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pub fn phase_index(&self) -> usize {
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*self as usize
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}
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}
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/// Where a specific `mir::Body` comes from.
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#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
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#[derive(HashStable, TyEncodable, TyDecodable, TypeFoldable)]
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pub struct MirSource<'tcx> {
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pub instance: InstanceDef<'tcx>,
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/// If `Some`, this is a promoted rvalue within the parent function.
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pub promoted: Option<Promoted>,
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}
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impl<'tcx> MirSource<'tcx> {
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pub fn item(def_id: DefId) -> Self {
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MirSource {
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instance: InstanceDef::Item(ty::WithOptConstParam::unknown(def_id)),
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promoted: None,
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}
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}
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pub fn from_instance(instance: InstanceDef<'tcx>) -> Self {
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MirSource { instance, promoted: None }
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}
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pub fn with_opt_param(self) -> ty::WithOptConstParam<DefId> {
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self.instance.with_opt_param()
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}
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#[inline]
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pub fn def_id(&self) -> DefId {
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self.instance.def_id()
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}
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}
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#[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable)]
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pub struct GeneratorInfo<'tcx> {
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/// The yield type of the function, if it is a generator.
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pub yield_ty: Option<Ty<'tcx>>,
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/// Generator drop glue.
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pub generator_drop: Option<Body<'tcx>>,
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/// The layout of a generator. Produced by the state transformation.
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pub generator_layout: Option<GeneratorLayout<'tcx>>,
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/// If this is a generator then record the type of source expression that caused this generator
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/// to be created.
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pub generator_kind: GeneratorKind,
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}
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/// The lowered representation of a single function.
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#[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable)]
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pub struct Body<'tcx> {
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/// A list of basic blocks. References to basic block use a newtyped index type [`BasicBlock`]
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/// that indexes into this vector.
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basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
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/// Records how far through the "desugaring and optimization" process this particular
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/// MIR has traversed. This is particularly useful when inlining, since in that context
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/// we instantiate the promoted constants and add them to our promoted vector -- but those
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/// promoted items have already been optimized, whereas ours have not. This field allows
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/// us to see the difference and forego optimization on the inlined promoted items.
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pub phase: MirPhase,
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pub source: MirSource<'tcx>,
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/// A list of source scopes; these are referenced by statements
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/// and used for debuginfo. Indexed by a `SourceScope`.
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pub source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
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pub generator: Option<Box<GeneratorInfo<'tcx>>>,
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/// Declarations of locals.
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///
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/// The first local is the return value pointer, followed by `arg_count`
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/// locals for the function arguments, followed by any user-declared
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/// variables and temporaries.
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pub local_decls: LocalDecls<'tcx>,
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/// User type annotations.
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pub user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
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/// The number of arguments this function takes.
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///
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/// Starting at local 1, `arg_count` locals will be provided by the caller
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/// and can be assumed to be initialized.
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///
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/// If this MIR was built for a constant, this will be 0.
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pub arg_count: usize,
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/// Mark an argument local (which must be a tuple) as getting passed as
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/// its individual components at the LLVM level.
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///
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/// This is used for the "rust-call" ABI.
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pub spread_arg: Option<Local>,
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/// Debug information pertaining to user variables, including captures.
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pub var_debug_info: Vec<VarDebugInfo<'tcx>>,
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/// A span representing this MIR, for error reporting.
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pub span: Span,
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/// Constants that are required to evaluate successfully for this MIR to be well-formed.
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/// We hold in this field all the constants we are not able to evaluate yet.
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pub required_consts: Vec<Constant<'tcx>>,
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/// Does this body use generic parameters. This is used for the `ConstEvaluatable` check.
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///
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/// Note that this does not actually mean that this body is not computable right now.
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/// The repeat count in the following example is polymorphic, but can still be evaluated
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/// without knowing anything about the type parameter `T`.
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///
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/// ```rust
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/// fn test<T>() {
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/// let _ = [0; std::mem::size_of::<*mut T>()];
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/// }
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/// ```
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///
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/// **WARNING**: Do not change this flags after the MIR was originally created, even if an optimization
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/// removed the last mention of all generic params. We do not want to rely on optimizations and
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/// potentially allow things like `[u8; std::mem::size_of::<T>() * 0]` due to this.
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pub is_polymorphic: bool,
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predecessor_cache: PredecessorCache,
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is_cyclic: GraphIsCyclicCache,
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}
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impl<'tcx> Body<'tcx> {
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pub fn new(
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source: MirSource<'tcx>,
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basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
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source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
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local_decls: LocalDecls<'tcx>,
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user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
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arg_count: usize,
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var_debug_info: Vec<VarDebugInfo<'tcx>>,
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span: Span,
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generator_kind: Option<GeneratorKind>,
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) -> Self {
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// We need `arg_count` locals, and one for the return place.
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assert!(
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local_decls.len() > arg_count,
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"expected at least {} locals, got {}",
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arg_count + 1,
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local_decls.len()
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);
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let mut body = Body {
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phase: MirPhase::Build,
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source,
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basic_blocks,
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source_scopes,
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generator: generator_kind.map(|generator_kind| {
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Box::new(GeneratorInfo {
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yield_ty: None,
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generator_drop: None,
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generator_layout: None,
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generator_kind,
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})
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}),
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local_decls,
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user_type_annotations,
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arg_count,
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spread_arg: None,
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var_debug_info,
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span,
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required_consts: Vec::new(),
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is_polymorphic: false,
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predecessor_cache: PredecessorCache::new(),
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is_cyclic: GraphIsCyclicCache::new(),
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};
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body.is_polymorphic = body.has_param_types_or_consts();
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body
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}
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/// Returns a partially initialized MIR body containing only a list of basic blocks.
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///
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/// The returned MIR contains no `LocalDecl`s (even for the return place) or source scopes. It
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/// is only useful for testing but cannot be `#[cfg(test)]` because it is used in a different
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/// crate.
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pub fn new_cfg_only(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>) -> Self {
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let mut body = Body {
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phase: MirPhase::Build,
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source: MirSource::item(DefId::local(CRATE_DEF_INDEX)),
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basic_blocks,
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source_scopes: IndexVec::new(),
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generator: None,
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local_decls: IndexVec::new(),
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user_type_annotations: IndexVec::new(),
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arg_count: 0,
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spread_arg: None,
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span: DUMMY_SP,
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required_consts: Vec::new(),
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var_debug_info: Vec::new(),
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is_polymorphic: false,
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predecessor_cache: PredecessorCache::new(),
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is_cyclic: GraphIsCyclicCache::new(),
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};
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body.is_polymorphic = body.has_param_types_or_consts();
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body
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}
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#[inline]
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pub fn basic_blocks(&self) -> &IndexVec<BasicBlock, BasicBlockData<'tcx>> {
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&self.basic_blocks
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}
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#[inline]
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pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
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// Because the user could mutate basic block terminators via this reference, we need to
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// invalidate the caches.
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//
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// FIXME: Use a finer-grained API for this, so only transformations that alter terminators
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// invalidate the caches.
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self.predecessor_cache.invalidate();
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self.is_cyclic.invalidate();
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&mut self.basic_blocks
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}
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#[inline]
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pub fn basic_blocks_and_local_decls_mut(
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&mut self,
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) -> (&mut IndexVec<BasicBlock, BasicBlockData<'tcx>>, &mut LocalDecls<'tcx>) {
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self.predecessor_cache.invalidate();
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self.is_cyclic.invalidate();
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(&mut self.basic_blocks, &mut self.local_decls)
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}
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#[inline]
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pub fn basic_blocks_local_decls_mut_and_var_debug_info(
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&mut self,
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) -> (
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&mut IndexVec<BasicBlock, BasicBlockData<'tcx>>,
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&mut LocalDecls<'tcx>,
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&mut Vec<VarDebugInfo<'tcx>>,
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) {
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self.predecessor_cache.invalidate();
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self.is_cyclic.invalidate();
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(&mut self.basic_blocks, &mut self.local_decls, &mut self.var_debug_info)
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}
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/// Returns `true` if a cycle exists in the control-flow graph that is reachable from the
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/// `START_BLOCK`.
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pub fn is_cfg_cyclic(&self) -> bool {
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self.is_cyclic.is_cyclic(self)
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}
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#[inline]
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pub fn local_kind(&self, local: Local) -> LocalKind {
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let index = local.as_usize();
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if index == 0 {
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debug_assert!(
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self.local_decls[local].mutability == Mutability::Mut,
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"return place should be mutable"
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);
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LocalKind::ReturnPointer
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} else if index < self.arg_count + 1 {
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LocalKind::Arg
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} else if self.local_decls[local].is_user_variable() {
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LocalKind::Var
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} else {
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LocalKind::Temp
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}
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}
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/// Returns an iterator over all temporaries.
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#[inline]
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pub fn temps_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
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(self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
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let local = Local::new(index);
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if self.local_decls[local].is_user_variable() { None } else { Some(local) }
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})
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}
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/// Returns an iterator over all user-declared locals.
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#[inline]
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pub fn vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
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(self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
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let local = Local::new(index);
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self.local_decls[local].is_user_variable().then_some(local)
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})
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}
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/// Returns an iterator over all user-declared mutable locals.
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#[inline]
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pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
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(self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
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let local = Local::new(index);
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let decl = &self.local_decls[local];
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if decl.is_user_variable() && decl.mutability == Mutability::Mut {
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Some(local)
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} else {
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None
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}
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})
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}
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|
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/// Returns an iterator over all user-declared mutable arguments and locals.
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#[inline]
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pub fn mut_vars_and_args_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
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(1..self.local_decls.len()).filter_map(move |index| {
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let local = Local::new(index);
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let decl = &self.local_decls[local];
|
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if (decl.is_user_variable() || index < self.arg_count + 1)
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&& decl.mutability == Mutability::Mut
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{
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Some(local)
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} else {
|
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None
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}
|
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})
|
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}
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|
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/// Returns an iterator over all function arguments.
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#[inline]
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pub fn args_iter(&self) -> impl Iterator<Item = Local> + ExactSizeIterator {
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let arg_count = self.arg_count;
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(1..arg_count + 1).map(Local::new)
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}
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/// Returns an iterator over all user-defined variables and compiler-generated temporaries (all
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/// locals that are neither arguments nor the return place).
|
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#[inline]
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pub fn vars_and_temps_iter(
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&self,
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) -> impl DoubleEndedIterator<Item = Local> + ExactSizeIterator {
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let arg_count = self.arg_count;
|
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let local_count = self.local_decls.len();
|
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(arg_count + 1..local_count).map(Local::new)
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}
|
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|
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/// Changes a statement to a nop. This is both faster than deleting instructions and avoids
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/// invalidating statement indices in `Location`s.
|
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pub fn make_statement_nop(&mut self, location: Location) {
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let block = &mut self.basic_blocks[location.block];
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debug_assert!(location.statement_index < block.statements.len());
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block.statements[location.statement_index].make_nop()
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}
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/// Returns the source info associated with `location`.
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pub fn source_info(&self, location: Location) -> &SourceInfo {
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let block = &self[location.block];
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||
let stmts = &block.statements;
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||
let idx = location.statement_index;
|
||
if idx < stmts.len() {
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&stmts[idx].source_info
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||
} else {
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assert_eq!(idx, stmts.len());
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&block.terminator().source_info
|
||
}
|
||
}
|
||
|
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/// Returns the return type; it always return first element from `local_decls` array.
|
||
#[inline]
|
||
pub fn return_ty(&self) -> Ty<'tcx> {
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self.local_decls[RETURN_PLACE].ty
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||
}
|
||
|
||
/// Gets the location of the terminator for the given block.
|
||
#[inline]
|
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pub fn terminator_loc(&self, bb: BasicBlock) -> Location {
|
||
Location { block: bb, statement_index: self[bb].statements.len() }
|
||
}
|
||
|
||
#[inline]
|
||
pub fn predecessors(&self) -> impl std::ops::Deref<Target = Predecessors> + '_ {
|
||
self.predecessor_cache.compute(&self.basic_blocks)
|
||
}
|
||
|
||
#[inline]
|
||
pub fn dominators(&self) -> Dominators<BasicBlock> {
|
||
dominators(self)
|
||
}
|
||
|
||
#[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)
|
||
}
|
||
}
|
||
|
||
#[derive(Copy, Clone, PartialEq, Eq, Debug, TyEncodable, TyDecodable, HashStable)]
|
||
pub enum Safety {
|
||
Safe,
|
||
/// Unsafe because of a PushUnsafeBlock
|
||
BuiltinUnsafe,
|
||
/// Unsafe because of an unsafe fn
|
||
FnUnsafe,
|
||
/// Unsafe because of an `unsafe` block
|
||
ExplicitUnsafe(hir::HirId),
|
||
}
|
||
|
||
impl<'tcx> Index<BasicBlock> for Body<'tcx> {
|
||
type Output = BasicBlockData<'tcx>;
|
||
|
||
#[inline]
|
||
fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
|
||
&self.basic_blocks()[index]
|
||
}
|
||
}
|
||
|
||
impl<'tcx> IndexMut<BasicBlock> for Body<'tcx> {
|
||
#[inline]
|
||
fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> {
|
||
&mut self.basic_blocks_mut()[index]
|
||
}
|
||
}
|
||
|
||
#[derive(Copy, Clone, Debug, HashStable, TypeFoldable)]
|
||
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 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<'tcx, E: TyEncoder<'tcx>, T: Encodable<E>> Encodable<E> for ClearCrossCrate<T> {
|
||
#[inline]
|
||
fn encode(&self, e: &mut E) -> Result<(), E::Error> {
|
||
if E::CLEAR_CROSS_CRATE {
|
||
return Ok(());
|
||
}
|
||
|
||
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<'tcx, D: TyDecoder<'tcx>, T: Decodable<D>> Decodable<D> for ClearCrossCrate<T> {
|
||
#[inline]
|
||
fn decode(d: &mut D) -> Result<ClearCrossCrate<T>, D::Error> {
|
||
if D::CLEAR_CROSS_CRATE {
|
||
return Ok(ClearCrossCrate::Clear);
|
||
}
|
||
|
||
let discr = u8::decode(d)?;
|
||
|
||
match discr {
|
||
TAG_CLEAR_CROSS_CRATE_CLEAR => Ok(ClearCrossCrate::Clear),
|
||
TAG_CLEAR_CROSS_CRATE_SET => {
|
||
let val = T::decode(d)?;
|
||
Ok(ClearCrossCrate::Set(val))
|
||
}
|
||
tag => Err(d.error(&format!("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 }
|
||
}
|
||
}
|
||
|
||
///////////////////////////////////////////////////////////////////////////
|
||
// Borrow kinds
|
||
|
||
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, TyEncodable, TyDecodable)]
|
||
#[derive(Hash, HashStable)]
|
||
pub enum BorrowKind {
|
||
/// Data must be immutable and is aliasable.
|
||
Shared,
|
||
|
||
/// The immediately borrowed place must be immutable, but projections from
|
||
/// it don't need to be. For example, a shallow borrow of `a.b` doesn't
|
||
/// conflict with a mutable borrow of `a.b.c`.
|
||
///
|
||
/// This is used when lowering matches: when matching on a place we want to
|
||
/// ensure that place have the same value from the start of the match until
|
||
/// an arm is selected. This prevents this code from compiling:
|
||
///
|
||
/// let mut x = &Some(0);
|
||
/// match *x {
|
||
/// None => (),
|
||
/// Some(_) if { x = &None; false } => (),
|
||
/// Some(_) => (),
|
||
/// }
|
||
///
|
||
/// This can't be a shared borrow because mutably borrowing (*x as Some).0
|
||
/// should not prevent `if let None = x { ... }`, for example, because the
|
||
/// mutating `(*x as Some).0` can't affect the discriminant of `x`.
|
||
/// We can also report errors with this kind of borrow differently.
|
||
Shallow,
|
||
|
||
/// Data must be immutable but not aliasable. This kind of borrow
|
||
/// cannot currently be expressed by the user and is used only in
|
||
/// implicit closure bindings. It is needed when the closure is
|
||
/// borrowing or mutating a mutable referent, e.g.:
|
||
///
|
||
/// let x: &mut isize = ...;
|
||
/// let y = || *x += 5;
|
||
///
|
||
/// If we were to try to translate this closure into a more explicit
|
||
/// form, we'd encounter an error with the code as written:
|
||
///
|
||
/// struct Env { x: & &mut isize }
|
||
/// let x: &mut isize = ...;
|
||
/// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
|
||
/// fn fn_ptr(env: &mut Env) { **env.x += 5; }
|
||
///
|
||
/// This is then illegal because you cannot mutate an `&mut` found
|
||
/// in an aliasable location. To solve, you'd have to translate with
|
||
/// an `&mut` borrow:
|
||
///
|
||
/// struct Env { x: & &mut isize }
|
||
/// let x: &mut isize = ...;
|
||
/// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
|
||
/// fn fn_ptr(env: &mut Env) { **env.x += 5; }
|
||
///
|
||
/// Now the assignment to `**env.x` is legal, but creating a
|
||
/// mutable pointer to `x` is not because `x` is not mutable. We
|
||
/// could fix this by declaring `x` as `let mut x`. This is ok in
|
||
/// user code, if awkward, but extra weird for closures, since the
|
||
/// borrow is hidden.
|
||
///
|
||
/// So we introduce a "unique imm" borrow -- the referent is
|
||
/// immutable, but not aliasable. This solves the problem. For
|
||
/// simplicity, we don't give users the way to express this
|
||
/// borrow, it's just used when translating closures.
|
||
Unique,
|
||
|
||
/// Data is mutable and not aliasable.
|
||
Mut {
|
||
/// `true` if this borrow arose from method-call auto-ref
|
||
/// (i.e., `adjustment::Adjust::Borrow`).
|
||
allow_two_phase_borrow: bool,
|
||
},
|
||
}
|
||
|
||
impl BorrowKind {
|
||
pub fn allows_two_phase_borrow(&self) -> bool {
|
||
match *self {
|
||
BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => false,
|
||
BorrowKind::Mut { allow_two_phase_borrow } => allow_two_phase_borrow,
|
||
}
|
||
}
|
||
}
|
||
|
||
///////////////////////////////////////////////////////////////////////////
|
||
// Variables and temps
|
||
|
||
rustc_index::newtype_index! {
|
||
pub struct Local {
|
||
derive [HashStable]
|
||
DEBUG_FORMAT = "_{}",
|
||
const RETURN_PLACE = 0,
|
||
}
|
||
}
|
||
|
||
impl Atom for Local {
|
||
fn index(self) -> usize {
|
||
Idx::index(self)
|
||
}
|
||
}
|
||
|
||
/// Classifies locals into categories. See `Body::local_kind`.
|
||
#[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable)]
|
||
pub enum LocalKind {
|
||
/// User-declared variable binding.
|
||
Var,
|
||
/// Compiler-introduced temporary.
|
||
Temp,
|
||
/// Function argument.
|
||
Arg,
|
||
/// Location of function's return value.
|
||
ReturnPointer,
|
||
}
|
||
|
||
#[derive(Clone, Debug, 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,
|
||
}
|
||
|
||
/// Represents what type of implicit self a function has, if any.
|
||
#[derive(Clone, Copy, PartialEq, Debug, TyEncodable, TyDecodable, HashStable)]
|
||
pub enum ImplicitSelfKind {
|
||
/// Represents a `fn x(self);`.
|
||
Imm,
|
||
/// Represents a `fn x(mut self);`.
|
||
Mut,
|
||
/// Represents a `fn x(&self);`.
|
||
ImmRef,
|
||
/// Represents a `fn x(&mut self);`.
|
||
MutRef,
|
||
/// Represents when a function does not have a self argument or
|
||
/// when a function has a `self: X` argument.
|
||
None,
|
||
}
|
||
|
||
TrivialTypeFoldableAndLiftImpls! { BindingForm<'tcx>, }
|
||
|
||
mod binding_form_impl {
|
||
use crate::ich::StableHashingContext;
|
||
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
|
||
|
||
impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
|
||
fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
|
||
use super::BindingForm::*;
|
||
std::mem::discriminant(self).hash_stable(hcx, hasher);
|
||
|
||
match self {
|
||
Var(binding) => binding.hash_stable(hcx, hasher),
|
||
ImplicitSelf(kind) => kind.hash_stable(hcx, hasher),
|
||
RefForGuard => (),
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/// `BlockTailInfo` is attached to the `LocalDecl` for temporaries
|
||
/// created during evaluation of expressions in a block tail
|
||
/// expression; that is, a block like `{ STMT_1; STMT_2; EXPR }`.
|
||
///
|
||
/// It is used to improve diagnostics when such temporaries are
|
||
/// involved in borrow_check errors, e.g., explanations of where the
|
||
/// temporaries come from, when their destructors are run, and/or how
|
||
/// one might revise the code to satisfy the borrow checker's rules.
|
||
#[derive(Clone, Debug, 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)]
|
||
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: Option<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
|
||
/// after typeck.
|
||
///
|
||
/// 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,
|
||
|
||
/// If this local is a temporary and `is_block_tail` is `Some`,
|
||
/// then it is a temporary created for evaluation of some
|
||
/// subexpression of some block's tail expression (with no
|
||
/// intervening statement context).
|
||
// FIXME(matthewjasper) Don't store in this in `Body`
|
||
pub is_block_tail: Option<BlockTailInfo>,
|
||
|
||
/// The type of this local.
|
||
pub ty: Ty<'tcx>,
|
||
|
||
/// If the user manually ascribed a type to this variable,
|
||
/// e.g., via `let x: T`, then we carry that type here. The MIR
|
||
/// borrow checker needs this information since it can affect
|
||
/// region inference.
|
||
// FIXME(matthewjasper) Don't store in this in `Body`
|
||
pub user_ty: 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().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,
|
||
}
|
||
|
||
// `LocalDecl` is used a lot. Make sure it doesn't unintentionally get bigger.
|
||
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
|
||
static_assert_size!(LocalDecl<'_>, 56);
|
||
|
||
/// 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)]
|
||
pub enum LocalInfo<'tcx> {
|
||
/// A user-defined local variable or function parameter
|
||
///
|
||
/// The `BindingForm` is solely used for local diagnostics when generating
|
||
/// warnings/errors when compiling the current crate, and therefore it need
|
||
/// not be visible across crates.
|
||
User(ClearCrossCrate<BindingForm<'tcx>>),
|
||
/// A temporary created that references the static with the given `DefId`.
|
||
StaticRef { def_id: DefId, is_thread_local: bool },
|
||
/// A temporary created that references the const with the given `DefId`
|
||
ConstRef { def_id: DefId },
|
||
}
|
||
|
||
impl<'tcx> LocalDecl<'tcx> {
|
||
/// Returns `true` only if local is a binding that can itself be
|
||
/// made mutable via the addition of the `mut` keyword, namely
|
||
/// something like the occurrences of `x` in:
|
||
/// - `fn foo(x: Type) { ... }`,
|
||
/// - `let x = ...`,
|
||
/// - or `match ... { C(x) => ... }`
|
||
pub fn can_be_made_mutable(&self) -> bool {
|
||
matches!(
|
||
self.local_info,
|
||
Some(box LocalInfo::User(ClearCrossCrate::Set(
|
||
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,
|
||
Some(box LocalInfo::User(ClearCrossCrate::Set(
|
||
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, Some(box 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,
|
||
Some(box LocalInfo::User(ClearCrossCrate::Set(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, Some(box 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 {
|
||
Some(box LocalInfo::StaticRef { is_thread_local, .. }) => is_thread_local,
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
/// Returns `true` is the local is from a compiler desugaring, e.g.,
|
||
/// `__next` from a `for` loop.
|
||
#[inline]
|
||
pub fn from_compiler_desugaring(&self) -> bool {
|
||
self.source_info.span.desugaring_kind().is_some()
|
||
}
|
||
|
||
/// Creates a new `LocalDecl` for a temporary: 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: None,
|
||
internal: false,
|
||
is_block_tail: None,
|
||
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
|
||
}
|
||
|
||
/// Converts `self` into same `LocalDecl` except tagged as internal temporary.
|
||
#[inline]
|
||
pub fn block_tail(mut self, info: BlockTailInfo) -> Self {
|
||
assert!(self.is_block_tail.is_none());
|
||
self.is_block_tail = Some(info);
|
||
self
|
||
}
|
||
}
|
||
|
||
#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable)]
|
||
pub enum VarDebugInfoContents<'tcx> {
|
||
/// NOTE(eddyb) There's an unenforced invariant that this `Place` is
|
||
/// based on a `Local`, not a `Static`, and contains no indexing.
|
||
Place(Place<'tcx>),
|
||
Const(Constant<'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),
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Debug information pertaining to a user variable.
|
||
#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)]
|
||
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>,
|
||
}
|
||
|
||
///////////////////////////////////////////////////////////////////////////
|
||
// 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_mir/transform/add_call_guards/enum.AddCallGuards.html#variant.CriticalCallEdges
|
||
/// [guide-mir]: https://rustc-dev-guide.rust-lang.org/mir/
|
||
pub struct BasicBlock {
|
||
derive [HashStable]
|
||
DEBUG_FORMAT = "bb{}",
|
||
const START_BLOCK = 0,
|
||
}
|
||
}
|
||
|
||
impl BasicBlock {
|
||
pub fn start_location(self) -> Location {
|
||
Location { block: self, statement_index: 0 }
|
||
}
|
||
}
|
||
|
||
///////////////////////////////////////////////////////////////////////////
|
||
// BasicBlockData and Terminator
|
||
|
||
/// See [`BasicBlock`] for documentation on what basic blocks are at a high level.
|
||
#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)]
|
||
pub struct BasicBlockData<'tcx> {
|
||
/// List of statements in this block.
|
||
pub statements: Vec<Statement<'tcx>>,
|
||
|
||
/// Terminator for this block.
|
||
///
|
||
/// N.B., this should generally ONLY be `None` during construction.
|
||
/// Therefore, you should generally access it via the
|
||
/// `terminator()` or `terminator_mut()` methods. The only
|
||
/// exception is that certain passes, such as `simplify_cfg`, swap
|
||
/// out the terminator temporarily with `None` while they continue
|
||
/// to recurse over the set of basic blocks.
|
||
pub terminator: Option<Terminator<'tcx>>,
|
||
|
||
/// If true, this block lies on an unwind path. This is used
|
||
/// during codegen where distinct kinds of basic blocks may be
|
||
/// generated (particularly for MSVC cleanup). Unwind blocks must
|
||
/// only branch to other unwind blocks.
|
||
pub is_cleanup: bool,
|
||
}
|
||
|
||
/// Information about an assertion failure.
|
||
#[derive(Clone, TyEncodable, TyDecodable, Hash, HashStable, PartialEq, PartialOrd)]
|
||
pub enum AssertKind<O> {
|
||
BoundsCheck { len: O, index: O },
|
||
Overflow(BinOp, O, O),
|
||
OverflowNeg(O),
|
||
DivisionByZero(O),
|
||
RemainderByZero(O),
|
||
ResumedAfterReturn(GeneratorKind),
|
||
ResumedAfterPanic(GeneratorKind),
|
||
}
|
||
|
||
#[derive(
|
||
Clone,
|
||
Debug,
|
||
PartialEq,
|
||
PartialOrd,
|
||
TyEncodable,
|
||
TyDecodable,
|
||
Hash,
|
||
HashStable,
|
||
TypeFoldable
|
||
)]
|
||
pub enum InlineAsmOperand<'tcx> {
|
||
In {
|
||
reg: InlineAsmRegOrRegClass,
|
||
value: Operand<'tcx>,
|
||
},
|
||
Out {
|
||
reg: InlineAsmRegOrRegClass,
|
||
late: bool,
|
||
place: Option<Place<'tcx>>,
|
||
},
|
||
InOut {
|
||
reg: InlineAsmRegOrRegClass,
|
||
late: bool,
|
||
in_value: Operand<'tcx>,
|
||
out_place: Option<Place<'tcx>>,
|
||
},
|
||
Const {
|
||
value: Operand<'tcx>,
|
||
},
|
||
SymFn {
|
||
value: Box<Constant<'tcx>>,
|
||
},
|
||
SymStatic {
|
||
def_id: DefId,
|
||
},
|
||
}
|
||
|
||
/// Type for MIR `Assert` terminator error messages.
|
||
pub type AssertMessage<'tcx> = AssertKind<Operand<'tcx>>;
|
||
|
||
pub type Successors<'a> =
|
||
iter::Chain<option::IntoIter<&'a BasicBlock>, slice::Iter<'a, BasicBlock>>;
|
||
pub type SuccessorsMut<'a> =
|
||
iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>;
|
||
|
||
impl<'tcx> BasicBlockData<'tcx> {
|
||
pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
|
||
BasicBlockData { statements: vec![], terminator, is_cleanup: false }
|
||
}
|
||
|
||
/// Accessor for terminator.
|
||
///
|
||
/// Terminator may not be None after construction of the basic block is complete. This accessor
|
||
/// provides a convenience way to reach the terminator.
|
||
pub fn terminator(&self) -> &Terminator<'tcx> {
|
||
self.terminator.as_ref().expect("invalid terminator state")
|
||
}
|
||
|
||
pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
|
||
self.terminator.as_mut().expect("invalid terminator state")
|
||
}
|
||
|
||
pub fn retain_statements<F>(&mut self, mut f: F)
|
||
where
|
||
F: FnMut(&mut Statement<'_>) -> bool,
|
||
{
|
||
for s in &mut self.statements {
|
||
if !f(s) {
|
||
s.make_nop();
|
||
}
|
||
}
|
||
}
|
||
|
||
pub fn expand_statements<F, I>(&mut self, mut f: F)
|
||
where
|
||
F: FnMut(&mut Statement<'tcx>) -> Option<I>,
|
||
I: iter::TrustedLen<Item = Statement<'tcx>>,
|
||
{
|
||
// Gather all the iterators we'll need to splice in, and their positions.
|
||
let mut splices: Vec<(usize, I)> = vec![];
|
||
let mut extra_stmts = 0;
|
||
for (i, s) in self.statements.iter_mut().enumerate() {
|
||
if let Some(mut new_stmts) = f(s) {
|
||
if let Some(first) = new_stmts.next() {
|
||
// We can already store the first new statement.
|
||
*s = first;
|
||
|
||
// Save the other statements for optimized splicing.
|
||
let remaining = new_stmts.size_hint().0;
|
||
if remaining > 0 {
|
||
splices.push((i + 1 + extra_stmts, new_stmts));
|
||
extra_stmts += remaining;
|
||
}
|
||
} else {
|
||
s.make_nop();
|
||
}
|
||
}
|
||
}
|
||
|
||
// Splice in the new statements, from the end of the block.
|
||
// FIXME(eddyb) This could be more efficient with a "gap buffer"
|
||
// where a range of elements ("gap") is left uninitialized, with
|
||
// splicing adding new elements to the end of that gap and moving
|
||
// existing elements from before the gap to the end of the gap.
|
||
// For now, this is safe code, emulating a gap but initializing it.
|
||
let mut gap = self.statements.len()..self.statements.len() + extra_stmts;
|
||
self.statements.resize(
|
||
gap.end,
|
||
Statement { source_info: SourceInfo::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 }
|
||
}
|
||
}
|
||
|
||
impl<O> AssertKind<O> {
|
||
/// Getting a description does not require `O` to be printable, and does not
|
||
/// require allocation.
|
||
/// The caller is expected to handle `BoundsCheck` 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 { .. } => bug!("Unexpected AssertKind"),
|
||
}
|
||
}
|
||
|
||
/// Format the message arguments for the `assert(cond, msg..)` terminator in MIR printing.
|
||
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)
|
||
}
|
||
_ => 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)
|
||
}
|
||
_ => write!(f, "{}", self.description()),
|
||
}
|
||
}
|
||
}
|
||
|
||
///////////////////////////////////////////////////////////////////////////
|
||
// Statements
|
||
|
||
#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable)]
|
||
pub struct Statement<'tcx> {
|
||
pub source_info: SourceInfo,
|
||
pub kind: StatementKind<'tcx>,
|
||
}
|
||
|
||
// `Statement` is used a lot. Make sure it doesn't unintentionally get bigger.
|
||
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
|
||
static_assert_size!(Statement<'_>, 32);
|
||
|
||
impl Statement<'_> {
|
||
/// Changes a statement to a nop. This is both faster than deleting instructions and avoids
|
||
/// invalidating statement indices in `Location`s.
|
||
pub fn make_nop(&mut self) {
|
||
self.kind = StatementKind::Nop
|
||
}
|
||
|
||
/// Changes a statement to a nop and returns the original statement.
|
||
pub fn replace_nop(&mut self) -> Self {
|
||
Statement {
|
||
source_info: self.source_info,
|
||
kind: mem::replace(&mut self.kind, StatementKind::Nop),
|
||
}
|
||
}
|
||
}
|
||
|
||
#[derive(Clone, Debug, PartialEq, TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable)]
|
||
pub enum StatementKind<'tcx> {
|
||
/// Write the RHS Rvalue to the LHS Place.
|
||
Assign(Box<(Place<'tcx>, Rvalue<'tcx>)>),
|
||
|
||
/// This represents all the reading that a pattern match may do
|
||
/// (e.g., inspecting constants and discriminant values), and the
|
||
/// kind of pattern it comes from. This is in order to adapt potential
|
||
/// error messages to these specific patterns.
|
||
///
|
||
/// Note that this also is emitted for regular `let` bindings to ensure that locals that are
|
||
/// never accessed still get some sanity checks for, e.g., `let x: ! = ..;`
|
||
FakeRead(FakeReadCause, Box<Place<'tcx>>),
|
||
|
||
/// Write the discriminant for a variant to the enum Place.
|
||
SetDiscriminant { place: Box<Place<'tcx>>, variant_index: VariantIdx },
|
||
|
||
/// Start a live range for the storage of the local.
|
||
StorageLive(Local),
|
||
|
||
/// End the current live range for the storage of the local.
|
||
StorageDead(Local),
|
||
|
||
/// Executes a piece of inline Assembly. Stored in a Box to keep the size
|
||
/// of `StatementKind` low.
|
||
LlvmInlineAsm(Box<LlvmInlineAsm<'tcx>>),
|
||
|
||
/// Retag references in the given place, ensuring they got fresh tags. This is
|
||
/// part of the Stacked Borrows model. These statements are currently only interpreted
|
||
/// by miri and only generated when "-Z mir-emit-retag" is passed.
|
||
/// See <https://internals.rust-lang.org/t/stacked-borrows-an-aliasing-model-for-rust/8153/>
|
||
/// for more details.
|
||
Retag(RetagKind, Box<Place<'tcx>>),
|
||
|
||
/// Encodes a user's type ascription. These need to be preserved
|
||
/// intact so that NLL can respect them. For example:
|
||
///
|
||
/// let a: T = y;
|
||
///
|
||
/// The effect of this annotation is to relate the type `T_y` of the place `y`
|
||
/// to the user-given type `T`. The effect depends on the specified variance:
|
||
///
|
||
/// - `Covariant` -- requires that `T_y <: T`
|
||
/// - `Contravariant` -- requires that `T_y :> T`
|
||
/// - `Invariant` -- requires that `T_y == T`
|
||
/// - `Bivariant` -- no effect
|
||
AscribeUserType(Box<(Place<'tcx>, UserTypeProjection)>, ty::Variance),
|
||
|
||
/// Marks the start of a "coverage region", injected with '-Zinstrument-coverage'. A
|
||
/// `CoverageInfo` statement carries metadata about the coverage region, used to inject a coverage
|
||
/// map into the binary. The `Counter` kind also generates executable code, to increment a
|
||
/// counter varible at runtime, each time the code region is executed.
|
||
Coverage(Box<Coverage>),
|
||
|
||
/// Denotes a call to the intrinsic function copy_overlapping, where `src_dst` denotes the
|
||
/// memory being read from and written to(one field to save memory), and size
|
||
/// indicates how many bytes are being copied over.
|
||
CopyNonOverlapping(Box<CopyNonOverlapping<'tcx>>),
|
||
|
||
/// No-op. Useful for deleting instructions without affecting statement indices.
|
||
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,
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Describes what kind of retag is to be performed.
|
||
#[derive(Copy, Clone, TyEncodable, TyDecodable, Debug, PartialEq, Eq, Hash, HashStable)]
|
||
pub enum RetagKind {
|
||
/// The initial retag when entering a function.
|
||
FnEntry,
|
||
/// Retag preparing for a two-phase borrow.
|
||
TwoPhase,
|
||
/// Retagging raw pointers.
|
||
Raw,
|
||
/// A "normal" retag.
|
||
Default,
|
||
}
|
||
|
||
/// The `FakeReadCause` describes the type of pattern why a FakeRead statement exists.
|
||
#[derive(Copy, Clone, TyEncodable, TyDecodable, Debug, Hash, HashStable, PartialEq)]
|
||
pub enum FakeReadCause {
|
||
/// Inject a fake read of the borrowed input at the end of each guards
|
||
/// code.
|
||
///
|
||
/// This should ensure that you cannot change the variant for an enum while
|
||
/// you are in the midst of matching on it.
|
||
ForMatchGuard,
|
||
|
||
/// `let x: !; match x {}` doesn't generate any read of x so we need to
|
||
/// generate a read of x to check that it is initialized and safe.
|
||
ForMatchedPlace,
|
||
|
||
/// A fake read of the RefWithinGuard version of a bind-by-value variable
|
||
/// in a match guard to ensure that it's value hasn't change by the time
|
||
/// we create the OutsideGuard version.
|
||
ForGuardBinding,
|
||
|
||
/// Officially, the semantics of
|
||
///
|
||
/// `let pattern = <expr>;`
|
||
///
|
||
/// is that `<expr>` is evaluated into a temporary and then this temporary is
|
||
/// into the pattern.
|
||
///
|
||
/// However, if we see the simple pattern `let var = <expr>`, we optimize this to
|
||
/// evaluate `<expr>` directly into the variable `var`. This is mostly unobservable,
|
||
/// but in some cases it can affect the borrow checker, as in #53695.
|
||
/// Therefore, we insert a "fake read" here to ensure that we get
|
||
/// appropriate errors.
|
||
ForLet,
|
||
|
||
/// If we have an index expression like
|
||
///
|
||
/// (*x)[1][{ x = y; 4}]
|
||
///
|
||
/// then the first bounds check is invalidated when we evaluate the second
|
||
/// index expression. Thus we create a fake borrow of `x` across the second
|
||
/// indexer, which will cause a borrow check error.
|
||
ForIndex,
|
||
}
|
||
|
||
#[derive(Clone, Debug, PartialEq, TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable)]
|
||
pub struct LlvmInlineAsm<'tcx> {
|
||
pub asm: hir::LlvmInlineAsmInner,
|
||
pub outputs: Box<[Place<'tcx>]>,
|
||
pub inputs: Box<[(Span, Operand<'tcx>)]>,
|
||
}
|
||
|
||
impl Debug for Statement<'_> {
|
||
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
|
||
use self::StatementKind::*;
|
||
match self.kind {
|
||
Assign(box (ref place, ref rv)) => write!(fmt, "{:?} = {:?}", place, rv),
|
||
FakeRead(ref cause, ref place) => write!(fmt, "FakeRead({:?}, {:?})", cause, place),
|
||
Retag(ref kind, ref place) => write!(
|
||
fmt,
|
||
"Retag({}{:?})",
|
||
match kind {
|
||
RetagKind::FnEntry => "[fn entry] ",
|
||
RetagKind::TwoPhase => "[2phase] ",
|
||
RetagKind::Raw => "[raw] ",
|
||
RetagKind::Default => "",
|
||
},
|
||
place,
|
||
),
|
||
StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place),
|
||
StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place),
|
||
SetDiscriminant { ref place, variant_index } => {
|
||
write!(fmt, "discriminant({:?}) = {:?}", place, variant_index)
|
||
}
|
||
LlvmInlineAsm(ref asm) => {
|
||
write!(fmt, "llvm_asm!({:?} : {:?} : {:?})", asm.asm, asm.outputs, asm.inputs)
|
||
}
|
||
AscribeUserType(box (ref place, ref c_ty), ref variance) => {
|
||
write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty)
|
||
}
|
||
Coverage(box ref coverage) => {
|
||
if let Some(rgn) = &coverage.code_region {
|
||
write!(fmt, "Coverage::{:?} for {:?}", coverage.kind, rgn)
|
||
} else {
|
||
write!(fmt, "Coverage::{:?}", coverage.kind)
|
||
}
|
||
}
|
||
CopyNonOverlapping(box crate::mir::CopyNonOverlapping {
|
||
ref src,
|
||
ref dst,
|
||
ref count,
|
||
}) => {
|
||
write!(fmt, "copy_nonoverlapping(src={:?}, dst={:?}, count={:?})", src, dst, count)
|
||
}
|
||
Nop => write!(fmt, "nop"),
|
||
}
|
||
}
|
||
}
|
||
|
||
#[derive(Clone, Debug, PartialEq, TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable)]
|
||
pub struct Coverage {
|
||
pub kind: CoverageKind,
|
||
pub code_region: Option<CodeRegion>,
|
||
}
|
||
|
||
#[derive(Clone, Debug, PartialEq, TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable)]
|
||
pub struct CopyNonOverlapping<'tcx> {
|
||
pub src: Operand<'tcx>,
|
||
pub dst: Operand<'tcx>,
|
||
/// Number of elements to copy from src to dest, not bytes.
|
||
pub count: Operand<'tcx>,
|
||
}
|
||
|
||
///////////////////////////////////////////////////////////////////////////
|
||
// Places
|
||
|
||
/// A path to a value; something that can be evaluated without
|
||
/// changing or disturbing program state.
|
||
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
|
||
pub struct Place<'tcx> {
|
||
pub local: Local,
|
||
|
||
/// projection out of a place (access a field, deref a pointer, etc)
|
||
pub projection: &'tcx List<PlaceElem<'tcx>>,
|
||
}
|
||
|
||
#[cfg(target_arch = "x86_64")]
|
||
static_assert_size!(Place<'_>, 16);
|
||
|
||
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
|
||
#[derive(TyEncodable, TyDecodable, HashStable)]
|
||
pub enum ProjectionElem<V, T> {
|
||
Deref,
|
||
Field(Field, T),
|
||
Index(V),
|
||
|
||
/// These indices are generated by slice patterns. Easiest to explain
|
||
/// by example:
|
||
///
|
||
/// ```
|
||
/// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
|
||
/// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
|
||
/// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
|
||
/// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
|
||
/// ```
|
||
ConstantIndex {
|
||
/// index or -index (in Python terms), depending on from_end
|
||
offset: u64,
|
||
/// The thing being indexed must be at least this long. For arrays this
|
||
/// is always the exact length.
|
||
min_length: u64,
|
||
/// Counting backwards from end? This is always false when indexing an
|
||
/// array.
|
||
from_end: bool,
|
||
},
|
||
|
||
/// These indices are generated by slice patterns.
|
||
///
|
||
/// If `from_end` is true `slice[from..slice.len() - to]`.
|
||
/// Otherwise `array[from..to]`.
|
||
Subslice {
|
||
from: u64,
|
||
to: u64,
|
||
/// Whether `to` counts from the start or end of the array/slice.
|
||
/// For `PlaceElem`s this is `true` if and only if the base is a slice.
|
||
/// For `ProjectionKind`, this can also be `true` for arrays.
|
||
from_end: bool,
|
||
},
|
||
|
||
/// "Downcast" to a variant of an ADT. Currently, we only introduce
|
||
/// this for ADTs with more than one variant. It may be better to
|
||
/// just introduce it always, or always for enums.
|
||
///
|
||
/// The included Symbol is the name of the variant, used for printing MIR.
|
||
Downcast(Option<Symbol>, VariantIdx),
|
||
}
|
||
|
||
impl<V, T> ProjectionElem<V, T> {
|
||
/// Returns `true` if the target of this projection may refer to a different region of memory
|
||
/// than the base.
|
||
fn is_indirect(&self) -> bool {
|
||
match self {
|
||
Self::Deref => true,
|
||
|
||
Self::Field(_, _)
|
||
| Self::Index(_)
|
||
| Self::ConstantIndex { .. }
|
||
| Self::Subslice { .. }
|
||
| Self::Downcast(_, _) => false,
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Alias for projections as they appear in places, where the base is a place
|
||
/// and the index is a local.
|
||
pub type PlaceElem<'tcx> = ProjectionElem<Local, Ty<'tcx>>;
|
||
|
||
// At least on 64 bit systems, `PlaceElem` should not be larger than two pointers.
|
||
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
|
||
static_assert_size!(PlaceElem<'_>, 24);
|
||
|
||
/// Alias for projections as they appear in `UserTypeProjection`, where we
|
||
/// need neither the `V` parameter for `Index` nor the `T` for `Field`.
|
||
pub type ProjectionKind = ProjectionElem<(), ()>;
|
||
|
||
rustc_index::newtype_index! {
|
||
pub struct Field {
|
||
derive [HashStable]
|
||
DEBUG_FORMAT = "field[{}]"
|
||
}
|
||
}
|
||
|
||
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
|
||
pub struct PlaceRef<'tcx> {
|
||
pub local: Local,
|
||
pub projection: &'tcx [PlaceElem<'tcx>],
|
||
}
|
||
|
||
impl<'tcx> Place<'tcx> {
|
||
// FIXME change this to a const fn by also making List::empty a const fn.
|
||
pub fn return_place() -> Place<'tcx> {
|
||
Place { local: RETURN_PLACE, projection: List::empty() }
|
||
}
|
||
|
||
/// Returns `true` if this `Place` contains a `Deref` projection.
|
||
///
|
||
/// If `Place::is_indirect` returns false, the caller knows that the `Place` refers to the
|
||
/// same region of memory as its base.
|
||
pub fn is_indirect(&self) -> bool {
|
||
self.projection.iter().any(|elem| elem.is_indirect())
|
||
}
|
||
|
||
/// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
|
||
/// a single deref of a local.
|
||
#[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.projection.iter().enumerate().map(move |(i, proj)| {
|
||
let base = PlaceRef { local: self.local, projection: &self.projection[..i] };
|
||
(base, proj)
|
||
})
|
||
}
|
||
}
|
||
|
||
impl From<Local> for Place<'_> {
|
||
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,
|
||
}
|
||
}
|
||
|
||
/// If this place represents a local variable like `_X` with no
|
||
/// projections, return `Some(_X)`.
|
||
pub fn as_local(&self) -> Option<Local> {
|
||
match *self {
|
||
PlaceRef { local, projection: [] } => Some(local),
|
||
_ => None,
|
||
}
|
||
}
|
||
|
||
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
|
||
}
|
||
}
|
||
}
|
||
|
||
impl Debug for Place<'_> {
|
||
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
|
||
for elem in self.projection.iter().rev() {
|
||
match elem {
|
||
ProjectionElem::Downcast(_, _) | ProjectionElem::Field(_, _) => {
|
||
write!(fmt, "(").unwrap();
|
||
}
|
||
ProjectionElem::Deref => {
|
||
write!(fmt, "(*").unwrap();
|
||
}
|
||
ProjectionElem::Index(_)
|
||
| ProjectionElem::ConstantIndex { .. }
|
||
| ProjectionElem::Subslice { .. } => {}
|
||
}
|
||
}
|
||
|
||
write!(fmt, "{:?}", self.local)?;
|
||
|
||
for elem in self.projection.iter() {
|
||
match elem {
|
||
ProjectionElem::Downcast(Some(name), _index) => {
|
||
write!(fmt, " as {})", name)?;
|
||
}
|
||
ProjectionElem::Downcast(None, index) => {
|
||
write!(fmt, " as variant#{:?})", index)?;
|
||
}
|
||
ProjectionElem::Deref => {
|
||
write!(fmt, ")")?;
|
||
}
|
||
ProjectionElem::Field(field, ty) => {
|
||
write!(fmt, ".{:?}: {:?})", field.index(), ty)?;
|
||
}
|
||
ProjectionElem::Index(ref index) => {
|
||
write!(fmt, "[{:?}]", index)?;
|
||
}
|
||
ProjectionElem::ConstantIndex { offset, min_length, from_end: false } => {
|
||
write!(fmt, "[{:?} of {:?}]", offset, min_length)?;
|
||
}
|
||
ProjectionElem::ConstantIndex { offset, min_length, from_end: true } => {
|
||
write!(fmt, "[-{:?} of {:?}]", offset, min_length)?;
|
||
}
|
||
ProjectionElem::Subslice { from, to, 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! {
|
||
pub struct SourceScope {
|
||
derive [HashStable]
|
||
DEBUG_FORMAT = "scope[{}]",
|
||
const OUTERMOST_SOURCE_SCOPE = 0,
|
||
}
|
||
}
|
||
|
||
#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)]
|
||
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
|
||
|
||
/// These are values that can appear inside an rvalue. They are intentionally
|
||
/// limited to prevent rvalues from being nested in one another.
|
||
#[derive(Clone, PartialEq, PartialOrd, TyEncodable, TyDecodable, Hash, HashStable)]
|
||
pub enum Operand<'tcx> {
|
||
/// Copy: The value must be available for use afterwards.
|
||
///
|
||
/// This implies that the type of the place must be `Copy`; this is true
|
||
/// by construction during build, but also checked by the MIR type checker.
|
||
Copy(Place<'tcx>),
|
||
|
||
/// Move: The value (including old borrows of it) will not be used again.
|
||
///
|
||
/// Safe for values of all types (modulo future developments towards `?Move`).
|
||
/// Correct usage patterns are enforced by the borrow checker for safe code.
|
||
/// `Copy` may be converted to `Move` to enable "last-use" optimizations.
|
||
Move(Place<'tcx>),
|
||
|
||
/// Synthesizes a constant value.
|
||
Constant(Box<Constant<'tcx>>),
|
||
}
|
||
|
||
#[cfg(target_arch = "x86_64")]
|
||
static_assert_size!(Operand<'_>, 24);
|
||
|
||
impl<'tcx> Debug for Operand<'tcx> {
|
||
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
|
||
use self::Operand::*;
|
||
match *self {
|
||
Constant(ref a) => write!(fmt, "{:?}", a),
|
||
Copy(ref place) => write!(fmt, "{:?}", place),
|
||
Move(ref place) => write!(fmt, "move {:?}", place),
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<'tcx> Operand<'tcx> {
|
||
/// Convenience helper to make a constant that refers to the fn
|
||
/// with given `DefId` and substs. Since this is used to synthesize
|
||
/// MIR, assumes `user_ty` is None.
|
||
pub fn function_handle(
|
||
tcx: TyCtxt<'tcx>,
|
||
def_id: DefId,
|
||
substs: SubstsRef<'tcx>,
|
||
span: Span,
|
||
) -> Self {
|
||
let ty = tcx.type_of(def_id).subst(tcx, substs);
|
||
Operand::Constant(box Constant {
|
||
span,
|
||
user_ty: None,
|
||
literal: ConstantKind::Ty(ty::Const::zero_sized(tcx, 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 Constant {
|
||
span,
|
||
user_ty: None,
|
||
literal: ConstantKind::Val(val.into(), 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,
|
||
}
|
||
}
|
||
}
|
||
|
||
///////////////////////////////////////////////////////////////////////////
|
||
/// Rvalues
|
||
|
||
#[derive(Clone, TyEncodable, TyDecodable, Hash, HashStable, PartialEq)]
|
||
pub enum Rvalue<'tcx> {
|
||
/// x (either a move or copy, depending on type of x)
|
||
Use(Operand<'tcx>),
|
||
|
||
/// [x; 32]
|
||
Repeat(Operand<'tcx>, &'tcx ty::Const<'tcx>),
|
||
|
||
/// &x or &mut x
|
||
Ref(Region<'tcx>, BorrowKind, Place<'tcx>),
|
||
|
||
/// Accessing a thread local static. This is inherently a runtime operation, even if llvm
|
||
/// treats it as an access to a static. This `Rvalue` yields a reference to the thread local
|
||
/// static.
|
||
ThreadLocalRef(DefId),
|
||
|
||
/// Create a raw pointer to the given place
|
||
/// Can be generated by raw address of expressions (`&raw const x`),
|
||
/// or when casting a reference to a raw pointer.
|
||
AddressOf(Mutability, Place<'tcx>),
|
||
|
||
/// length of a `[X]` or `[X;n]` value
|
||
Len(Place<'tcx>),
|
||
|
||
Cast(CastKind, Operand<'tcx>, Ty<'tcx>),
|
||
|
||
BinaryOp(BinOp, Box<(Operand<'tcx>, Operand<'tcx>)>),
|
||
CheckedBinaryOp(BinOp, Box<(Operand<'tcx>, Operand<'tcx>)>),
|
||
|
||
NullaryOp(NullOp, Ty<'tcx>),
|
||
UnaryOp(UnOp, Operand<'tcx>),
|
||
|
||
/// Read the discriminant of an ADT.
|
||
///
|
||
/// Undefined (i.e., no effort is made to make it defined, but there’s no reason why it cannot
|
||
/// be defined to return, say, a 0) if ADT is not an enum.
|
||
Discriminant(Place<'tcx>),
|
||
|
||
/// Creates an aggregate value, like a tuple or struct. This is
|
||
/// only needed because we want to distinguish `dest = Foo { x:
|
||
/// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case
|
||
/// that `Foo` has a destructor. These rvalues can be optimized
|
||
/// away after type-checking and before lowering.
|
||
Aggregate(Box<AggregateKind<'tcx>>, Vec<Operand<'tcx>>),
|
||
}
|
||
|
||
#[cfg(target_arch = "x86_64")]
|
||
static_assert_size!(Rvalue<'_>, 40);
|
||
|
||
#[derive(Clone, Copy, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
|
||
pub enum CastKind {
|
||
Misc,
|
||
Pointer(PointerCast),
|
||
}
|
||
|
||
#[derive(Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
|
||
pub enum AggregateKind<'tcx> {
|
||
/// The type is of the element
|
||
Array(Ty<'tcx>),
|
||
Tuple,
|
||
|
||
/// The second field is the variant index. It's equal to 0 for struct
|
||
/// and union expressions. The fourth field is
|
||
/// active field number and is present only for union expressions
|
||
/// -- e.g., for a union expression `SomeUnion { c: .. }`, the
|
||
/// active field index would identity the field `c`
|
||
Adt(&'tcx AdtDef, VariantIdx, SubstsRef<'tcx>, Option<UserTypeAnnotationIndex>, Option<usize>),
|
||
|
||
Closure(DefId, SubstsRef<'tcx>),
|
||
Generator(DefId, SubstsRef<'tcx>, hir::Movability),
|
||
}
|
||
|
||
#[cfg(target_arch = "x86_64")]
|
||
static_assert_size!(AggregateKind<'_>, 48);
|
||
|
||
#[derive(Copy, Clone, Debug, PartialEq, PartialOrd, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
|
||
pub enum BinOp {
|
||
/// The `+` operator (addition)
|
||
Add,
|
||
/// The `-` operator (subtraction)
|
||
Sub,
|
||
/// The `*` operator (multiplication)
|
||
Mul,
|
||
/// The `/` operator (division)
|
||
Div,
|
||
/// The `%` operator (modulus)
|
||
Rem,
|
||
/// The `^` operator (bitwise xor)
|
||
BitXor,
|
||
/// The `&` operator (bitwise and)
|
||
BitAnd,
|
||
/// The `|` operator (bitwise or)
|
||
BitOr,
|
||
/// The `<<` operator (shift left)
|
||
Shl,
|
||
/// The `>>` operator (shift right)
|
||
Shr,
|
||
/// The `==` operator (equality)
|
||
Eq,
|
||
/// The `<` operator (less than)
|
||
Lt,
|
||
/// The `<=` operator (less than or equal to)
|
||
Le,
|
||
/// The `!=` operator (not equal to)
|
||
Ne,
|
||
/// The `>=` operator (greater than or equal to)
|
||
Ge,
|
||
/// The `>` operator (greater than)
|
||
Gt,
|
||
/// The `ptr.offset` operator
|
||
Offset,
|
||
}
|
||
|
||
impl BinOp {
|
||
pub fn is_checkable(self) -> bool {
|
||
use self::BinOp::*;
|
||
matches!(self, Add | Sub | Mul | Shl | Shr)
|
||
}
|
||
}
|
||
|
||
#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
|
||
pub enum NullOp {
|
||
/// Returns the size of a value of that type
|
||
SizeOf,
|
||
/// Creates a new uninitialized box for a value of that type
|
||
Box,
|
||
}
|
||
|
||
#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
|
||
pub enum UnOp {
|
||
/// The `!` operator for logical inversion
|
||
Not,
|
||
/// The `-` operator for negation
|
||
Neg,
|
||
}
|
||
|
||
impl<'tcx> Debug for Rvalue<'tcx> {
|
||
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
|
||
use self::Rvalue::*;
|
||
|
||
match *self {
|
||
Use(ref place) => write!(fmt, "{:?}", place),
|
||
Repeat(ref a, ref b) => {
|
||
write!(fmt, "[{:?}; ", a)?;
|
||
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) => write!(fmt, "{:?}({:?})", op, t),
|
||
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.debugging_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)
|
||
}
|
||
|
||
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_def, variant, substs, _user_ty, _) => {
|
||
let variant_def = &adt_def.variants[variant];
|
||
|
||
let name = ty::tls::with(|tcx| {
|
||
let mut name = String::new();
|
||
let substs = tcx.lift(substs).expect("could not lift for printing");
|
||
FmtPrinter::new(tcx, &mut name, Namespace::ValueNS)
|
||
.print_def_path(variant_def.def_id, substs)?;
|
||
Ok(name)
|
||
})?;
|
||
|
||
match variant_def.ctor_kind {
|
||
CtorKind::Const => fmt.write_str(&name),
|
||
CtorKind::Fn => fmt_tuple(fmt, &name),
|
||
CtorKind::Fictive => {
|
||
let mut struct_fmt = fmt.debug_struct(&name);
|
||
for (field, place) in variant_def.fields.iter().zip(places) {
|
||
struct_fmt.field(&field.ident.as_str(), place);
|
||
}
|
||
struct_fmt.finish()
|
||
}
|
||
}
|
||
}
|
||
|
||
AggregateKind::Closure(def_id, substs) => ty::tls::with(|tcx| {
|
||
if let Some(def_id) = def_id.as_local() {
|
||
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
|
||
let name = if tcx.sess.opts.debugging_opts.span_free_formats {
|
||
let substs = tcx.lift(substs).unwrap();
|
||
format!(
|
||
"[closure@{}]",
|
||
tcx.def_path_str_with_substs(def_id.to_def_id(), substs),
|
||
)
|
||
} else {
|
||
let span = tcx.hir().span(hir_id);
|
||
format!("[closure@{}]", tcx.sess.source_map().span_to_string(span))
|
||
};
|
||
let mut struct_fmt = fmt.debug_struct(&name);
|
||
|
||
if let Some(upvars) = tcx.upvars_mentioned(def_id) {
|
||
for (&var_id, place) in upvars.keys().zip(places) {
|
||
let var_name = tcx.hir().name(var_id);
|
||
struct_fmt.field(&var_name.as_str(), place);
|
||
}
|
||
}
|
||
|
||
struct_fmt.finish()
|
||
} else {
|
||
write!(fmt, "[closure]")
|
||
}
|
||
}),
|
||
|
||
AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
|
||
if let Some(def_id) = def_id.as_local() {
|
||
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
|
||
let name = format!("[generator@{:?}]", tcx.hir().span(hir_id));
|
||
let mut struct_fmt = fmt.debug_struct(&name);
|
||
|
||
if let Some(upvars) = tcx.upvars_mentioned(def_id) {
|
||
for (&var_id, place) in upvars.keys().zip(places) {
|
||
let var_name = tcx.hir().name(var_id);
|
||
struct_fmt.field(&var_name.as_str(), place);
|
||
}
|
||
}
|
||
|
||
struct_fmt.finish()
|
||
} else {
|
||
write!(fmt, "[generator]")
|
||
}
|
||
}),
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
///////////////////////////////////////////////////////////////////////////
|
||
/// Constants
|
||
///
|
||
/// Two constants are equal if they are the same constant. Note that
|
||
/// this does not necessarily mean that they are `==` in Rust. In
|
||
/// particular, one must be wary of `NaN`!
|
||
|
||
#[derive(Clone, Copy, PartialEq, PartialOrd, TyEncodable, TyDecodable, Hash, HashStable)]
|
||
pub struct Constant<'tcx> {
|
||
pub span: Span,
|
||
|
||
/// Optional user-given type: for something like
|
||
/// `collect::<Vec<_>>`, this would be present and would
|
||
/// indicate that `Vec<_>` was explicitly specified.
|
||
///
|
||
/// Needed for NLL to impose user-given type constraints.
|
||
pub user_ty: Option<UserTypeAnnotationIndex>,
|
||
|
||
pub literal: ConstantKind<'tcx>,
|
||
}
|
||
|
||
#[derive(Clone, Copy, PartialEq, PartialOrd, TyEncodable, TyDecodable, Hash, HashStable, Debug)]
|
||
pub enum ConstantKind<'tcx> {
|
||
/// This constant came from the type system
|
||
Ty(&'tcx ty::Const<'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 Constant<'tcx> {
|
||
pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option<DefId> {
|
||
match self.literal.const_for_ty()?.val.try_to_scalar() {
|
||
Some(Scalar::Ptr(ptr)) => match tcx.global_alloc(ptr.alloc_id) {
|
||
GlobalAlloc::Static(def_id) => {
|
||
assert!(!tcx.is_thread_local_static(def_id));
|
||
Some(def_id)
|
||
}
|
||
_ => None,
|
||
},
|
||
_ => None,
|
||
}
|
||
}
|
||
pub fn ty(&self) -> Ty<'tcx> {
|
||
self.literal.ty()
|
||
}
|
||
}
|
||
|
||
impl From<&'tcx ty::Const<'tcx>> for ConstantKind<'tcx> {
|
||
fn from(ct: &'tcx ty::Const<'tcx>) -> Self {
|
||
Self::Ty(ct)
|
||
}
|
||
}
|
||
|
||
impl ConstantKind<'tcx> {
|
||
/// Returns `None` if the constant is not trivially safe for use in the type system.
|
||
pub fn const_for_ty(&self) -> Option<&'tcx ty::Const<'tcx>> {
|
||
match self {
|
||
ConstantKind::Ty(c) => Some(c),
|
||
ConstantKind::Val(..) => None,
|
||
}
|
||
}
|
||
|
||
pub fn ty(&self) -> Ty<'tcx> {
|
||
match self {
|
||
ConstantKind::Ty(c) => c.ty,
|
||
ConstantKind::Val(_, ty) => ty,
|
||
}
|
||
}
|
||
|
||
#[inline]
|
||
pub fn try_to_value(self) -> Option<interpret::ConstValue<'tcx>> {
|
||
match self {
|
||
ConstantKind::Ty(c) => c.val.try_to_value(),
|
||
ConstantKind::Val(val, _) => Some(val),
|
||
}
|
||
}
|
||
|
||
#[inline]
|
||
pub fn try_to_scalar(self) -> Option<Scalar> {
|
||
self.try_to_value()?.try_to_scalar()
|
||
}
|
||
|
||
#[inline]
|
||
pub fn try_to_scalar_int(self) -> Option<ScalarInt> {
|
||
Some(self.try_to_value()?.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 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)
|
||
}
|
||
}
|
||
}
|
||
|
||
#[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(),
|
||
}
|
||
}
|
||
|
||
#[inline]
|
||
pub fn try_eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Option<u64> {
|
||
match self {
|
||
Self::Ty(ct) => ct.try_eval_usize(tcx, param_env),
|
||
Self::Val(val, _) => val.try_to_machine_usize(tcx),
|
||
}
|
||
}
|
||
}
|
||
|
||
/// A collection of projections into user types.
|
||
///
|
||
/// They are projections because a binding can occur a part of a
|
||
/// parent pattern that has been ascribed a type.
|
||
///
|
||
/// Its a collection because there can be multiple type ascriptions on
|
||
/// the path from the root of the pattern down to the binding itself.
|
||
///
|
||
/// An example:
|
||
///
|
||
/// ```rust
|
||
/// struct S<'a>((i32, &'a str), String);
|
||
/// let S((_, w): (i32, &'static str), _): S = ...;
|
||
/// // ------ ^^^^^^^^^^^^^^^^^^^ (1)
|
||
/// // --------------------------------- ^ (2)
|
||
/// ```
|
||
///
|
||
/// The highlights labelled `(1)` show the subpattern `(_, w)` being
|
||
/// ascribed the type `(i32, &'static str)`.
|
||
///
|
||
/// The highlights labelled `(2)` show the whole pattern being
|
||
/// ascribed the type `S`.
|
||
///
|
||
/// In this example, when we descend to `w`, we will have built up the
|
||
/// following two projected types:
|
||
///
|
||
/// * base: `S`, projection: `(base.0).1`
|
||
/// * base: `(i32, &'static str)`, projection: `base.1`
|
||
///
|
||
/// The first will lead to the constraint `w: &'1 str` (for some
|
||
/// inferred region `'1`). The second will lead to the constraint `w:
|
||
/// &'static str`.
|
||
#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)]
|
||
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.drain(..).map(|(proj, span)| (f(proj), span)).collect();
|
||
self
|
||
}
|
||
|
||
pub fn index(self) -> Self {
|
||
self.map_projections(|pat_ty_proj| pat_ty_proj.index())
|
||
}
|
||
|
||
pub fn subslice(self, from: 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: Field) -> Self {
|
||
self.map_projections(|pat_ty_proj| pat_ty_proj.leaf(field))
|
||
}
|
||
|
||
pub fn variant(self, adt_def: &'tcx AdtDef, variant_index: VariantIdx, field: Field) -> Self {
|
||
self.map_projections(|pat_ty_proj| pat_ty_proj.variant(adt_def, variant_index, field))
|
||
}
|
||
}
|
||
|
||
/// Encodes the effect of a user-supplied type annotation on the
|
||
/// subcomponents of a pattern. The effect is determined by applying the
|
||
/// given list of proejctions to some underlying base type. Often,
|
||
/// the projection element list `projs` is empty, in which case this
|
||
/// directly encodes a type in `base`. But in the case of complex patterns with
|
||
/// subpatterns and bindings, we want to apply only a *part* of the type to a variable,
|
||
/// in which case the `projs` vector is used.
|
||
///
|
||
/// Examples:
|
||
///
|
||
/// * `let x: T = ...` -- here, the `projs` vector is empty.
|
||
///
|
||
/// * `let (x, _): T = ...` -- here, the `projs` vector would contain
|
||
/// `field[0]` (aka `.0`), indicating that the type of `s` is
|
||
/// determined by finding the type of the `.0` field from `T`.
|
||
#[derive(Clone, Debug, TyEncodable, TyDecodable, Hash, HashStable, PartialEq)]
|
||
pub struct UserTypeProjection {
|
||
pub base: UserTypeAnnotationIndex,
|
||
pub projs: Vec<ProjectionKind>,
|
||
}
|
||
|
||
impl Copy for ProjectionKind {}
|
||
|
||
impl UserTypeProjection {
|
||
pub(crate) fn index(mut self) -> Self {
|
||
self.projs.push(ProjectionElem::Index(()));
|
||
self
|
||
}
|
||
|
||
pub(crate) fn subslice(mut self, from: 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: Field) -> Self {
|
||
self.projs.push(ProjectionElem::Field(field, ()));
|
||
self
|
||
}
|
||
|
||
pub(crate) fn variant(
|
||
mut self,
|
||
adt_def: &AdtDef,
|
||
variant_index: VariantIdx,
|
||
field: Field,
|
||
) -> Self {
|
||
self.projs.push(ProjectionElem::Downcast(
|
||
Some(adt_def.variants[variant_index].ident.name),
|
||
variant_index,
|
||
));
|
||
self.projs.push(ProjectionElem::Field(field, ()));
|
||
self
|
||
}
|
||
}
|
||
|
||
TrivialTypeFoldableAndLiftImpls! { ProjectionKind, }
|
||
|
||
impl<'tcx> TypeFoldable<'tcx> for UserTypeProjection {
|
||
fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
|
||
UserTypeProjection {
|
||
base: self.base.fold_with(folder),
|
||
projs: self.projs.fold_with(folder),
|
||
}
|
||
}
|
||
|
||
fn super_visit_with<Vs: TypeVisitor<'tcx>>(
|
||
&self,
|
||
visitor: &mut Vs,
|
||
) -> ControlFlow<Vs::BreakTy> {
|
||
self.base.visit_with(visitor)
|
||
// Note: there's nothing in `self.proj` to visit.
|
||
}
|
||
}
|
||
|
||
rustc_index::newtype_index! {
|
||
pub struct Promoted {
|
||
derive [HashStable]
|
||
DEBUG_FORMAT = "promoted[{}]"
|
||
}
|
||
}
|
||
|
||
impl<'tcx> Debug for Constant<'tcx> {
|
||
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
|
||
write!(fmt, "{}", self)
|
||
}
|
||
}
|
||
|
||
impl<'tcx> Display for Constant<'tcx> {
|
||
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
|
||
match self.ty().kind() {
|
||
ty::FnDef(..) => {}
|
||
_ => write!(fmt, "const ")?,
|
||
}
|
||
match self.literal {
|
||
ConstantKind::Ty(c) => pretty_print_const(c, fmt, true),
|
||
ConstantKind::Val(val, ty) => pretty_print_const_value(val, ty, fmt, true),
|
||
}
|
||
}
|
||
}
|
||
|
||
fn pretty_print_const(
|
||
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, fmt, Namespace::ValueNS);
|
||
cx.print_alloc_ids = true;
|
||
cx.pretty_print_const(literal, print_types)?;
|
||
Ok(())
|
||
})
|
||
}
|
||
|
||
fn pretty_print_const_value(
|
||
val: interpret::ConstValue<'tcx>,
|
||
ty: Ty<'tcx>,
|
||
fmt: &mut Formatter<'_>,
|
||
print_types: bool,
|
||
) -> fmt::Result {
|
||
use crate::ty::print::PrettyPrinter;
|
||
ty::tls::with(|tcx| {
|
||
let val = tcx.lift(val).unwrap();
|
||
let ty = tcx.lift(ty).unwrap();
|
||
let mut cx = FmtPrinter::new(tcx, fmt, Namespace::ValueNS);
|
||
cx.print_alloc_ids = true;
|
||
cx.pretty_print_const_value(val, ty, print_types)?;
|
||
Ok(())
|
||
})
|
||
}
|
||
|
||
impl<'tcx> graph::DirectedGraph for Body<'tcx> {
|
||
type Node = BasicBlock;
|
||
}
|
||
|
||
impl<'tcx> graph::WithNumNodes for Body<'tcx> {
|
||
#[inline]
|
||
fn num_nodes(&self) -> usize {
|
||
self.basic_blocks.len()
|
||
}
|
||
}
|
||
|
||
impl<'tcx> graph::WithStartNode for Body<'tcx> {
|
||
#[inline]
|
||
fn start_node(&self) -> Self::Node {
|
||
START_BLOCK
|
||
}
|
||
}
|
||
|
||
impl<'tcx> graph::WithSuccessors for Body<'tcx> {
|
||
#[inline]
|
||
fn successors(&self, node: Self::Node) -> <Self as GraphSuccessors<'_>>::Iter {
|
||
self.basic_blocks[node].terminator().successors().cloned()
|
||
}
|
||
}
|
||
|
||
impl<'a, 'b> graph::GraphSuccessors<'b> for Body<'a> {
|
||
type Item = BasicBlock;
|
||
type Iter = iter::Cloned<Successors<'b>>;
|
||
}
|
||
|
||
impl graph::GraphPredecessors<'graph> for Body<'tcx> {
|
||
type Item = BasicBlock;
|
||
type Iter = smallvec::IntoIter<[BasicBlock; 4]>;
|
||
}
|
||
|
||
impl graph::WithPredecessors for Body<'tcx> {
|
||
#[inline]
|
||
fn predecessors(&self, node: Self::Node) -> <Self as graph::GraphPredecessors<'_>>::Iter {
|
||
self.predecessors()[node].clone().into_iter()
|
||
}
|
||
}
|
||
|
||
/// `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.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 it's 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.is_dominated_by(other.block, self.block)
|
||
}
|
||
}
|
||
}
|