diff options
Diffstat (limited to 'compiler/rustc_middle/src/mir/syntax.rs')
| -rw-r--r-- | compiler/rustc_middle/src/mir/syntax.rs | 118 |
1 files changed, 95 insertions, 23 deletions
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs index be27bf75d..0b95fdfa1 100644 --- a/compiler/rustc_middle/src/mir/syntax.rs +++ b/compiler/rustc_middle/src/mir/syntax.rs @@ -3,7 +3,7 @@ //! This is in a dedicated file so that changes to this file can be reviewed more carefully. //! The intention is that this file only contains datatype declarations, no code. -use super::{BasicBlock, Constant, Local, SwitchTargets, UserTypeProjection}; +use super::{BasicBlock, Const, Local, UserTypeProjection}; use crate::mir::coverage::{CodeRegion, CoverageKind}; use crate::traits::Reveal; @@ -24,6 +24,7 @@ use rustc_span::def_id::LocalDefId; use rustc_span::symbol::Symbol; use rustc_span::Span; use rustc_target::asm::InlineAsmRegOrRegClass; +use smallvec::SmallVec; /// Represents the "flavors" of MIR. /// @@ -122,7 +123,7 @@ pub enum AnalysisPhase { /// * [`TerminatorKind::FalseEdge`] /// * [`StatementKind::FakeRead`] /// * [`StatementKind::AscribeUserType`] - /// * [`Rvalue::Ref`] with `BorrowKind::Shallow` + /// * [`Rvalue::Ref`] with `BorrowKind::Fake` /// /// Furthermore, `Deref` projections must be the first projection within any place (if they /// appear at all) @@ -138,6 +139,7 @@ pub enum RuntimePhase { /// * [`TerminatorKind::Yield`] /// * [`TerminatorKind::GeneratorDrop`] /// * [`Rvalue::Aggregate`] for any `AggregateKind` except `Array` + /// * [`PlaceElem::OpaqueCast`] /// /// And the following variants are allowed: /// * [`StatementKind::Retag`] @@ -180,7 +182,7 @@ pub enum BorrowKind { /// 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, + Fake, /// Data is mutable and not aliasable. Mut { kind: MutBorrowKind }, @@ -380,6 +382,28 @@ pub enum StatementKind<'tcx> { Nop, } +impl StatementKind<'_> { + /// Returns a simple string representation of a `StatementKind` variant, independent of any + /// values it might hold (e.g. `StatementKind::Assign` always returns `"Assign"`). + pub const fn name(&self) -> &'static str { + match self { + StatementKind::Assign(..) => "Assign", + StatementKind::FakeRead(..) => "FakeRead", + StatementKind::SetDiscriminant { .. } => "SetDiscriminant", + StatementKind::Deinit(..) => "Deinit", + StatementKind::StorageLive(..) => "StorageLive", + StatementKind::StorageDead(..) => "StorageDead", + StatementKind::Retag(..) => "Retag", + StatementKind::PlaceMention(..) => "PlaceMention", + StatementKind::AscribeUserType(..) => "AscribeUserType", + StatementKind::Coverage(..) => "Coverage", + StatementKind::Intrinsic(..) => "Intrinsic", + StatementKind::ConstEvalCounter => "ConstEvalCounter", + StatementKind::Nop => "Nop", + } + } +} + #[derive( Clone, TyEncodable, @@ -416,17 +440,6 @@ pub enum NonDivergingIntrinsic<'tcx> { CopyNonOverlapping(CopyNonOverlapping<'tcx>), } -impl std::fmt::Display for NonDivergingIntrinsic<'_> { - fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { - match self { - Self::Assume(op) => write!(f, "assume({op:?})"), - Self::CopyNonOverlapping(CopyNonOverlapping { src, dst, count }) => { - write!(f, "copy_nonoverlapping(dst = {dst:?}, src = {src:?}, count = {count:?})") - } - } - } -} - /// Describes what kind of retag is to be performed. #[derive(Copy, Clone, TyEncodable, TyDecodable, Debug, PartialEq, Eq, Hash, HashStable)] #[rustc_pass_by_value] @@ -593,13 +606,13 @@ pub enum TerminatorKind<'tcx> { /// /// Only permitted in cleanup blocks. `Resume` is not permitted with `-C unwind=abort` after /// deaggregation runs. - Resume, + UnwindResume, /// Indicates that the landing pad is finished and that the process should terminate. /// /// Used to prevent unwinding for foreign items or with `-C unwind=abort`. Only permitted in /// cleanup blocks. - Terminate, + UnwindTerminate(UnwindTerminateReason), /// Returns from the function. /// @@ -790,8 +803,8 @@ impl TerminatorKind<'_> { match self { TerminatorKind::Goto { .. } => "Goto", TerminatorKind::SwitchInt { .. } => "SwitchInt", - TerminatorKind::Resume => "Resume", - TerminatorKind::Terminate => "Terminate", + TerminatorKind::UnwindResume => "UnwindResume", + TerminatorKind::UnwindTerminate(_) => "UnwindTerminate", TerminatorKind::Return => "Return", TerminatorKind::Unreachable => "Unreachable", TerminatorKind::Drop { .. } => "Drop", @@ -806,6 +819,27 @@ impl TerminatorKind<'_> { } } +#[derive(Debug, Clone, TyEncodable, TyDecodable, Hash, HashStable, PartialEq)] +pub struct SwitchTargets { + /// Possible values. The locations to branch to in each case + /// are found in the corresponding indices from the `targets` vector. + pub(super) values: SmallVec<[u128; 1]>, + + /// Possible branch sites. The last element of this vector is used + /// for the otherwise branch, so targets.len() == values.len() + 1 + /// should hold. + // + // This invariant is quite non-obvious and also could be improved. + // One way to make this invariant is to have something like this instead: + // + // branches: Vec<(ConstInt, BasicBlock)>, + // otherwise: Option<BasicBlock> // exhaustive if None + // + // However we’ve decided to keep this as-is until we figure a case + // where some other approach seems to be strictly better than other. + pub(super) targets: SmallVec<[BasicBlock; 2]>, +} + /// Action to be taken when a stack unwind happens. #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)] #[derive(TypeFoldable, TypeVisitable)] @@ -820,11 +854,22 @@ pub enum UnwindAction { /// Terminates the execution if unwind happens. /// /// Depending on the platform and situation this may cause a non-unwindable panic or abort. - Terminate, + Terminate(UnwindTerminateReason), /// Cleanups to be done. Cleanup(BasicBlock), } +/// The reason we are terminating the process during unwinding. +#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)] +#[derive(TypeFoldable, TypeVisitable)] +pub enum UnwindTerminateReason { + /// Unwinding is just not possible given the ABI of this function. + Abi, + /// We were already cleaning up for an ongoing unwind, and a *second*, *nested* unwind was + /// triggered by the drop glue. + InCleanup, +} + /// Information about an assertion failure. #[derive(Clone, Hash, HashStable, PartialEq, Debug)] #[derive(TyEncodable, TyDecodable, TypeFoldable, TypeVisitable)] @@ -858,10 +903,10 @@ pub enum InlineAsmOperand<'tcx> { out_place: Option<Place<'tcx>>, }, Const { - value: Box<Constant<'tcx>>, + value: Box<ConstOperand<'tcx>>, }, SymFn { - value: Box<Constant<'tcx>>, + value: Box<ConstOperand<'tcx>>, }, SymStatic { def_id: DefId, @@ -1030,6 +1075,18 @@ pub enum ProjectionElem<V, T> { /// Like an explicit cast from an opaque type to a concrete type, but without /// requiring an intermediate variable. OpaqueCast(T), + + /// A `Subtype(T)` projection is applied to any `StatementKind::Assign` where + /// type of lvalue doesn't match the type of rvalue, the primary goal is making subtyping + /// explicit during optimizations and codegen. + /// + /// This projection doesn't impact the runtime behavior of the program except for potentially changing + /// some type metadata of the interpreter or codegen backend. + /// + /// This goal is achieved with mir_transform pass `Subtyper`, which runs right after + /// borrowchecker, as we only care about subtyping that can affect trait selection and + /// `TypeId`. + Subtype(T), } /// Alias for projections as they appear in places, where the base is a place @@ -1081,7 +1138,22 @@ pub enum Operand<'tcx> { Move(Place<'tcx>), /// Constants are already semantically values, and remain unchanged. - Constant(Box<Constant<'tcx>>), + Constant(Box<ConstOperand<'tcx>>), +} + +#[derive(Clone, Copy, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)] +#[derive(TypeFoldable, TypeVisitable)] +pub struct ConstOperand<'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 const_: Const<'tcx>, } /////////////////////////////////////////////////////////////////////////// @@ -1274,7 +1346,7 @@ pub enum AggregateKind<'tcx> { Generator(DefId, GenericArgsRef<'tcx>, hir::Movability), } -#[derive(Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)] +#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)] pub enum NullOp<'tcx> { /// Returns the size of a value of that type SizeOf, |