compiler/rustc_middle/src/mir/tcx.rs

   1 /*!
   2  * Methods for the various MIR types. These are intended for use after
   3  * building is complete.
   4  */
   5
   6 use crate::mir::*;
   7 use crate::ty::{self, Ty, TyCtxt};
   8 use rustc_hir as hir;
   9 use rustc_target::abi::VariantIdx;
  10
  11 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
  12 pub struct PlaceTy<'tcx> {
  13     pub ty: Ty<'tcx>,
  14     /// Downcast to a particular variant of an enum or a generator, if included.
  15     pub variant_index: Option<VariantIdx>,
  16 }
  17
  18 // At least on 64 bit systems, `PlaceTy` should not be larger than two or three pointers.
  19 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
  20 static_assert_size!(PlaceTy<'_>, 16);
  21
  22 impl<'tcx> PlaceTy<'tcx> {
  23     #[inline]
  24     pub fn from_ty(ty: Ty<'tcx>) -> PlaceTy<'tcx> {
  25         PlaceTy { ty, variant_index: None }
  26     }
  27
  28     /// `place_ty.field_ty(tcx, f)` computes the type at a given field
  29     /// of a record or enum-variant. (Most clients of `PlaceTy` can
  30     /// instead just extract the relevant type directly from their
  31     /// `PlaceElem`, but some instances of `ProjectionElem<V, T>` do
  32     /// not carry a `Ty` for `T`.)
  33     ///
  34     /// Note that the resulting type has not been normalized.
  35     #[instrument(level = "debug", skip(tcx), ret)]
  36     pub fn field_ty(self, tcx: TyCtxt<'tcx>, f: Field) -> Ty<'tcx> {
  37         match self.ty.kind() {
  38             ty::Adt(adt_def, substs) => {
  39                 let variant_def = match self.variant_index {
  40                     None => adt_def.non_enum_variant(),
  41                     Some(variant_index) => {
  42                         assert!(adt_def.is_enum());
  43                         &adt_def.variant(variant_index)
  44                     }
  45                 };
  46                 let field_def = &variant_def.fields[f.index()];
  47                 field_def.ty(tcx, substs)
  48             }
  49             ty::Tuple(tys) => tys[f.index()],
  50             _ => bug!("extracting field of non-tuple non-adt: {:?}", self),
  51         }
  52     }
  53
  54     /// Convenience wrapper around `projection_ty_core` for
  55     /// `PlaceElem`, where we can just use the `Ty` that is already
  56     /// stored inline on field projection elems.
  57     pub fn projection_ty(self, tcx: TyCtxt<'tcx>, elem: PlaceElem<'tcx>) -> PlaceTy<'tcx> {
  58         self.projection_ty_core(tcx, ty::ParamEnv::empty(), &elem, |_, _, ty| ty, |_, ty| ty)
  59     }
  60
  61     /// `place_ty.projection_ty_core(tcx, elem, |...| { ... })`
  62     /// projects `place_ty` onto `elem`, returning the appropriate
  63     /// `Ty` or downcast variant corresponding to that projection.
  64     /// The `handle_field` callback must map a `Field` to its `Ty`,
  65     /// (which should be trivial when `T` = `Ty`).
  66     pub fn projection_ty_core<V, T>(
  67         self,
  68         tcx: TyCtxt<'tcx>,
  69         param_env: ty::ParamEnv<'tcx>,
  70         elem: &ProjectionElem<V, T>,
  71         mut handle_field: impl FnMut(&Self, Field, T) -> Ty<'tcx>,
  72         mut handle_opaque_cast: impl FnMut(&Self, T) -> Ty<'tcx>,
  73     ) -> PlaceTy<'tcx>
  74     where
  75         V: ::std::fmt::Debug,
  76         T: ::std::fmt::Debug + Copy,
  77     {
  78         if self.variant_index.is_some() && !matches!(elem, ProjectionElem::Field(..)) {
  79             bug!("cannot use non field projection on downcasted place")
  80         }
  81         let answer = match *elem {
  82             ProjectionElem::Deref => {
  83                 let ty = self
  84                     .ty
  85                     .builtin_deref(true)
  86                     .unwrap_or_else(|| {
  87                         bug!("deref projection of non-dereferenceable ty {:?}", self)
  88                     })
  89                     .ty;
  90                 PlaceTy::from_ty(ty)
  91             }
  92             ProjectionElem::Index(_) | ProjectionElem::ConstantIndex { .. } => {
  93                 PlaceTy::from_ty(self.ty.builtin_index().unwrap())
  94             }
  95             ProjectionElem::Subslice { from, to, from_end } => {
  96                 PlaceTy::from_ty(match self.ty.kind() {
  97                     ty::Slice(..) => self.ty,
  98                     ty::Array(inner, _) if !from_end => tcx.mk_array(*inner, (to - from) as u64),
  99                     ty::Array(inner, size) if from_end => {
 100                         let size = size.eval_usize(tcx, param_env);
 101                         let len = size - (from as u64) - (to as u64);
 102                         tcx.mk_array(*inner, len)
 103                     }
 104                     _ => bug!("cannot subslice non-array type: `{:?}`", self),
 105                 })
 106             }
 107             ProjectionElem::Downcast(_name, index) => {
 108                 PlaceTy { ty: self.ty, variant_index: Some(index) }
 109             }
 110             ProjectionElem::Field(f, fty) => PlaceTy::from_ty(handle_field(&self, f, fty)),
 111             ProjectionElem::OpaqueCast(ty) => PlaceTy::from_ty(handle_opaque_cast(&self, ty)),
 112         };
 113         debug!("projection_ty self: {:?} elem: {:?} yields: {:?}", self, elem, answer);
 114         answer
 115     }
 116 }
 117
 118 impl<'tcx> Place<'tcx> {
 119     pub fn ty_from<D>(
 120         local: Local,
 121         projection: &[PlaceElem<'tcx>],
 122         local_decls: &D,
 123         tcx: TyCtxt<'tcx>,
 124     ) -> PlaceTy<'tcx>
 125     where
 126         D: HasLocalDecls<'tcx>,
 127     {
 128         projection
 129             .iter()
 130             .fold(PlaceTy::from_ty(local_decls.local_decls()[local].ty), |place_ty, &elem| {
 131                 place_ty.projection_ty(tcx, elem)
 132             })
 133     }
 134
 135     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> PlaceTy<'tcx>
 136     where
 137         D: HasLocalDecls<'tcx>,
 138     {
 139         Place::ty_from(self.local, &self.projection, local_decls, tcx)
 140     }
 141 }
 142
 143 impl<'tcx> PlaceRef<'tcx> {
 144     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> PlaceTy<'tcx>
 145     where
 146         D: HasLocalDecls<'tcx>,
 147     {
 148         Place::ty_from(self.local, &self.projection, local_decls, tcx)
 149     }
 150 }
 151
 152 pub enum RvalueInitializationState {
 153     Shallow,
 154     Deep,
 155 }
 156
 157 impl<'tcx> Rvalue<'tcx> {
 158     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx>
 159     where
 160         D: HasLocalDecls<'tcx>,
 161     {
 162         match *self {
 163             Rvalue::Use(ref operand) => operand.ty(local_decls, tcx),
 164             Rvalue::Repeat(ref operand, count) => {
 165                 tcx.mk_ty(ty::Array(operand.ty(local_decls, tcx), count))
 166             }
 167             Rvalue::ThreadLocalRef(did) => {
 168                 let static_ty = tcx.type_of(did);
 169                 if tcx.is_mutable_static(did) {
 170                     tcx.mk_mut_ptr(static_ty)
 171                 } else if tcx.is_foreign_item(did) {
 172                     tcx.mk_imm_ptr(static_ty)
 173                 } else {
 174                     // FIXME: These things don't *really* have 'static lifetime.
 175                     tcx.mk_imm_ref(tcx.lifetimes.re_static, static_ty)
 176                 }
 177             }
 178             Rvalue::Ref(reg, bk, ref place) => {
 179                 let place_ty = place.ty(local_decls, tcx).ty;
 180                 tcx.mk_ref(reg, ty::TypeAndMut { ty: place_ty, mutbl: bk.to_mutbl_lossy() })
 181             }
 182             Rvalue::AddressOf(mutability, ref place) => {
 183                 let place_ty = place.ty(local_decls, tcx).ty;
 184                 tcx.mk_ptr(ty::TypeAndMut { ty: place_ty, mutbl: mutability })
 185             }
 186             Rvalue::Len(..) => tcx.types.usize,
 187             Rvalue::Cast(.., ty) => ty,
 188             Rvalue::BinaryOp(op, box (ref lhs, ref rhs)) => {
 189                 let lhs_ty = lhs.ty(local_decls, tcx);
 190                 let rhs_ty = rhs.ty(local_decls, tcx);
 191                 op.ty(tcx, lhs_ty, rhs_ty)
 192             }
 193             Rvalue::CheckedBinaryOp(op, box (ref lhs, ref rhs)) => {
 194                 let lhs_ty = lhs.ty(local_decls, tcx);
 195                 let rhs_ty = rhs.ty(local_decls, tcx);
 196                 let ty = op.ty(tcx, lhs_ty, rhs_ty);
 197                 tcx.intern_tup(&[ty, tcx.types.bool])
 198             }
 199             Rvalue::UnaryOp(UnOp::Not | UnOp::Neg, ref operand) => operand.ty(local_decls, tcx),
 200             Rvalue::Discriminant(ref place) => place.ty(local_decls, tcx).ty.discriminant_ty(tcx),
 201             Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _) => tcx.types.usize,
 202             Rvalue::Aggregate(ref ak, ref ops) => match **ak {
 203                 AggregateKind::Array(ty) => tcx.mk_array(ty, ops.len() as u64),
 204                 AggregateKind::Tuple => tcx.mk_tup(ops.iter().map(|op| op.ty(local_decls, tcx))),
 205                 AggregateKind::Adt(did, _, substs, _, _) => {
 206                     tcx.bound_type_of(did).subst(tcx, substs)
 207                 }
 208                 AggregateKind::Closure(did, substs) => tcx.mk_closure(did.to_def_id(), substs),
 209                 AggregateKind::Generator(did, substs, movability) => {
 210                     tcx.mk_generator(did.to_def_id(), substs, movability)
 211                 }
 212             },
 213             Rvalue::ShallowInitBox(_, ty) => tcx.mk_box(ty),
 214             Rvalue::CopyForDeref(ref place) => place.ty(local_decls, tcx).ty,
 215         }
 216     }
 217
 218     #[inline]
 219     /// Returns `true` if this rvalue is deeply initialized (most rvalues) or
 220     /// whether its only shallowly initialized (`Rvalue::Box`).
 221     pub fn initialization_state(&self) -> RvalueInitializationState {
 222         match *self {
 223             Rvalue::ShallowInitBox(_, _) => RvalueInitializationState::Shallow,
 224             _ => RvalueInitializationState::Deep,
 225         }
 226     }
 227 }
 228
 229 impl<'tcx> Operand<'tcx> {
 230     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx>
 231     where
 232         D: HasLocalDecls<'tcx>,
 233     {
 234         match self {
 235             &Operand::Copy(ref l) | &Operand::Move(ref l) => l.ty(local_decls, tcx).ty,
 236             Operand::Constant(c) => c.literal.ty(),
 237         }
 238     }
 239 }
 240
 241 impl<'tcx> BinOp {
 242     pub fn ty(&self, tcx: TyCtxt<'tcx>, lhs_ty: Ty<'tcx>, rhs_ty: Ty<'tcx>) -> Ty<'tcx> {
 243         // FIXME: handle SIMD correctly
 244         match self {
 245             &BinOp::Add
 246             | &BinOp::Sub
 247             | &BinOp::Mul
 248             | &BinOp::Div
 249             | &BinOp::Rem
 250             | &BinOp::BitXor
 251             | &BinOp::BitAnd
 252             | &BinOp::BitOr => {
 253                 // these should be integers or floats of the same size.
 254                 assert_eq!(lhs_ty, rhs_ty);
 255                 lhs_ty
 256             }
 257             &BinOp::Shl | &BinOp::Shr | &BinOp::Offset => {
 258                 lhs_ty // lhs_ty can be != rhs_ty
 259             }
 260             &BinOp::Eq | &BinOp::Lt | &BinOp::Le | &BinOp::Ne | &BinOp::Ge | &BinOp::Gt => {
 261                 tcx.types.bool
 262             }
 263         }
 264     }
 265 }
 266
 267 impl BorrowKind {
 268     pub fn to_mutbl_lossy(self) -> hir::Mutability {
 269         match self {
 270             BorrowKind::Mut { .. } => hir::Mutability::Mut,
 271             BorrowKind::Shared => hir::Mutability::Not,
 272
 273             // We have no type corresponding to a unique imm borrow, so
 274             // use `&mut`. It gives all the capabilities of a `&uniq`
 275             // and hence is a safe "over approximation".
 276             BorrowKind::Unique => hir::Mutability::Mut,
 277
 278             // We have no type corresponding to a shallow borrow, so use
 279             // `&` as an approximation.
 280             BorrowKind::Shallow => hir::Mutability::Not,
 281         }
 282     }
 283 }
 284
 285 impl BinOp {
 286     pub fn to_hir_binop(self) -> hir::BinOpKind {
 287         match self {
 288             BinOp::Add => hir::BinOpKind::Add,
 289             BinOp::Sub => hir::BinOpKind::Sub,
 290             BinOp::Mul => hir::BinOpKind::Mul,
 291             BinOp::Div => hir::BinOpKind::Div,
 292             BinOp::Rem => hir::BinOpKind::Rem,
 293             BinOp::BitXor => hir::BinOpKind::BitXor,
 294             BinOp::BitAnd => hir::BinOpKind::BitAnd,
 295             BinOp::BitOr => hir::BinOpKind::BitOr,
 296             BinOp::Shl => hir::BinOpKind::Shl,
 297             BinOp::Shr => hir::BinOpKind::Shr,
 298             BinOp::Eq => hir::BinOpKind::Eq,
 299             BinOp::Ne => hir::BinOpKind::Ne,
 300             BinOp::Lt => hir::BinOpKind::Lt,
 301             BinOp::Gt => hir::BinOpKind::Gt,
 302             BinOp::Le => hir::BinOpKind::Le,
 303             BinOp::Ge => hir::BinOpKind::Ge,
 304             BinOp::Offset => unreachable!(),
 305         }
 306     }
 307 }