src/librustc/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::subst::Subst;
   8 use crate::ty::{self, Ty, TyCtxt};
   9 use crate::ty::layout::VariantIdx;
  10 use crate::hir;
  11 use crate::ty::util::IntTypeExt;
  12
  13 #[derive(Copy, Clone, Debug, TypeFoldable)]
  14 pub struct PlaceTy<'tcx> {
  15     pub ty: Ty<'tcx>,
  16     /// Downcast to a particular variant of an enum, if included.
  17     pub variant_index: Option<VariantIdx>,
  18 }
  19
  20 // At least on 64 bit systems, `PlaceTy` should not be larger than two or three pointers.
  21 #[cfg(target_arch = "x86_64")]
  22 static_assert_size!(PlaceTy<'_>, 16);
  23
  24 impl<'tcx> PlaceTy<'tcx> {
  25     pub fn from_ty(ty: Ty<'tcx>) -> PlaceTy<'tcx> {
  26         PlaceTy { ty, variant_index: None }
  27     }
  28
  29     /// `place_ty.field_ty(tcx, f)` computes the type at a given field
  30     /// of a record or enum-variant. (Most clients of `PlaceTy` can
  31     /// instead just extract the relevant type directly from their
  32     /// `PlaceElem`, but some instances of `ProjectionElem<V, T>` do
  33     /// not carry a `Ty` for `T`.)
  34     ///
  35     /// Note that the resulting type has not been normalized.
  36     pub fn field_ty(self, tcx: TyCtxt<'tcx>, f: &Field) -> Ty<'tcx> {
  37         let answer = 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.variants[variant_index]
  44                     }
  45                 };
  46                 let field_def = &variant_def.fields[f.index()];
  47                 field_def.ty(tcx, substs)
  48             }
  49             ty::Tuple(ref tys) => tys[f.index()].expect_ty(),
  50             _ => bug!("extracting field of non-tuple non-adt: {:?}", self),
  51         };
  52         debug!("field_ty self: {:?} f: {:?} yields: {:?}", self, f, answer);
  53         answer
  54     }
  55
  56     /// Convenience wrapper around `projection_ty_core` for
  57     /// `PlaceElem`, where we can just use the `Ty` that is already
  58     /// stored inline on field projection elems.
  59     pub fn projection_ty(self, tcx: TyCtxt<'tcx>, elem: &PlaceElem<'tcx>) -> PlaceTy<'tcx> {
  60         self.projection_ty_core(tcx, ty::ParamEnv::empty(), elem, |_, _, ty| ty)
  61     }
  62
  63     /// `place_ty.projection_ty_core(tcx, elem, |...| { ... })`
  64     /// projects `place_ty` onto `elem`, returning the appropriate
  65     /// `Ty` or downcast variant corresponding to that projection.
  66     /// The `handle_field` callback must map a `Field` to its `Ty`,
  67     /// (which should be trivial when `T` = `Ty`).
  68     pub fn projection_ty_core<V, T>(
  69         self,
  70         tcx: TyCtxt<'tcx>,
  71         param_env: ty::ParamEnv<'tcx>,
  72         elem: &ProjectionElem<V, T>,
  73         mut handle_field: impl FnMut(&Self, &Field, &T) -> Ty<'tcx>,
  74     ) -> PlaceTy<'tcx>
  75     where
  76         V: ::std::fmt::Debug,
  77         T: ::std::fmt::Debug,
  78     {
  79         let answer = match *elem {
  80             ProjectionElem::Deref => {
  81                 let ty = self.ty
  82                              .builtin_deref(true)
  83                              .unwrap_or_else(|| {
  84                                  bug!("deref projection of non-dereferenceable ty {:?}", self)
  85                              })
  86                              .ty;
  87                 PlaceTy::from_ty(ty)
  88             }
  89             ProjectionElem::Index(_) | ProjectionElem::ConstantIndex { .. } =>
  90                 PlaceTy::from_ty(self.ty.builtin_index().unwrap()),
  91             ProjectionElem::Subslice { from, to, from_end } => {
  92                 PlaceTy::from_ty(match self.ty.kind {
  93                     ty::Slice(..) => self.ty,
  94                     ty::Array(inner, _) if !from_end => {
  95                         tcx.mk_array(inner, (to - from) as u64)
  96                     }
  97                     ty::Array(inner, size) if from_end => {
  98                         let size = size.eval_usize(tcx, param_env);
  99                         let len = size - (from as u64) - (to as u64);
 100                         tcx.mk_array(inner, len)
 101                     }
 102                     _ => {
 103                         bug!("cannot subslice non-array type: `{:?}`", self)
 104                     }
 105                 })
 106             }
 107             ProjectionElem::Downcast(_name, index) =>
 108                 PlaceTy { ty: self.ty, variant_index: Some(index) },
 109             ProjectionElem::Field(ref f, ref fty) =>
 110                 PlaceTy::from_ty(handle_field(&self, f, fty)),
 111         };
 112         debug!("projection_ty self: {:?} elem: {:?} yields: {:?}", self, elem, answer);
 113         answer
 114     }
 115 }
 116
 117 impl<'tcx> Place<'tcx> {
 118     pub fn ty_from<D>(
 119         base: &PlaceBase<'tcx>,
 120         projection: &[PlaceElem<'tcx>],
 121         local_decls: &D,
 122         tcx: TyCtxt<'tcx>
 123     ) -> PlaceTy<'tcx>
 124         where D: HasLocalDecls<'tcx>
 125     {
 126         projection.iter().fold(
 127             base.ty(local_decls),
 128             |place_ty, elem| place_ty.projection_ty(tcx, elem)
 129         )
 130     }
 131
 132     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> PlaceTy<'tcx>
 133     where
 134         D: HasLocalDecls<'tcx>,
 135     {
 136         Place::ty_from(&self.base, &self.projection, local_decls, tcx)
 137     }
 138 }
 139
 140 impl<'tcx> PlaceBase<'tcx> {
 141     pub fn ty<D>(&self, local_decls: &D) -> PlaceTy<'tcx>
 142         where D: HasLocalDecls<'tcx>
 143     {
 144         match self {
 145             PlaceBase::Local(index) => PlaceTy::from_ty(local_decls.local_decls()[*index].ty),
 146             PlaceBase::Static(data) => PlaceTy::from_ty(data.ty),
 147         }
 148     }
 149 }
 150
 151 pub enum RvalueInitializationState {
 152     Shallow,
 153     Deep
 154 }
 155
 156 impl<'tcx> Rvalue<'tcx> {
 157     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx>
 158     where
 159         D: HasLocalDecls<'tcx>,
 160     {
 161         match *self {
 162             Rvalue::Use(ref operand) => operand.ty(local_decls, tcx),
 163             Rvalue::Repeat(ref operand, count) => {
 164                 tcx.mk_array(operand.ty(local_decls, tcx), count)
 165             }
 166             Rvalue::Ref(reg, bk, ref place) => {
 167                 let place_ty = place.ty(local_decls, tcx).ty;
 168                 tcx.mk_ref(reg,
 169                     ty::TypeAndMut {
 170                         ty: place_ty,
 171                         mutbl: bk.to_mutbl_lossy()
 172                     }
 173                 )
 174             }
 175             Rvalue::Len(..) => tcx.types.usize,
 176             Rvalue::Cast(.., ty) => ty,
 177             Rvalue::BinaryOp(op, ref lhs, ref rhs) => {
 178                 let lhs_ty = lhs.ty(local_decls, tcx);
 179                 let rhs_ty = rhs.ty(local_decls, tcx);
 180                 op.ty(tcx, lhs_ty, rhs_ty)
 181             }
 182             Rvalue::CheckedBinaryOp(op, ref lhs, ref rhs) => {
 183                 let lhs_ty = lhs.ty(local_decls, tcx);
 184                 let rhs_ty = rhs.ty(local_decls, tcx);
 185                 let ty = op.ty(tcx, lhs_ty, rhs_ty);
 186                 tcx.intern_tup(&[ty, tcx.types.bool])
 187             }
 188             Rvalue::UnaryOp(UnOp::Not, ref operand) |
 189             Rvalue::UnaryOp(UnOp::Neg, ref operand) => {
 190                 operand.ty(local_decls, tcx)
 191             }
 192             Rvalue::Discriminant(ref place) => {
 193                 let ty = place.ty(local_decls, tcx).ty;
 194                 match ty.kind {
 195                     ty::Adt(adt_def, _) => adt_def.repr.discr_type().to_ty(tcx),
 196                     ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
 197                     _ => {
 198                         // This can only be `0`, for now, so `u8` will suffice.
 199                         tcx.types.u8
 200                     }
 201                 }
 202             }
 203             Rvalue::NullaryOp(NullOp::Box, t) => tcx.mk_box(t),
 204             Rvalue::NullaryOp(NullOp::SizeOf, _) => tcx.types.usize,
 205             Rvalue::Aggregate(ref ak, ref ops) => {
 206                 match **ak {
 207                     AggregateKind::Array(ty) => {
 208                         tcx.mk_array(ty, ops.len() as u64)
 209                     }
 210                     AggregateKind::Tuple => {
 211                         tcx.mk_tup(ops.iter().map(|op| op.ty(local_decls, tcx)))
 212                     }
 213                     AggregateKind::Adt(def, _, substs, _, _) => {
 214                         tcx.type_of(def.did).subst(tcx, substs)
 215                     }
 216                     AggregateKind::Closure(did, substs) => {
 217                         tcx.mk_closure(did, substs)
 218                     }
 219                     AggregateKind::Generator(did, substs, movability) => {
 220                         tcx.mk_generator(did, substs, movability)
 221                     }
 222                 }
 223             }
 224         }
 225     }
 226
 227     #[inline]
 228     /// Returns `true` if this rvalue is deeply initialized (most rvalues) or
 229     /// whether its only shallowly initialized (`Rvalue::Box`).
 230     pub fn initialization_state(&self) -> RvalueInitializationState {
 231         match *self {
 232             Rvalue::NullaryOp(NullOp::Box, _) => RvalueInitializationState::Shallow,
 233             _ => RvalueInitializationState::Deep
 234         }
 235     }
 236 }
 237
 238 impl<'tcx> Operand<'tcx> {
 239     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx>
 240     where
 241         D: HasLocalDecls<'tcx>,
 242     {
 243         match self {
 244             &Operand::Copy(ref l) |
 245             &Operand::Move(ref l) => l.ty(local_decls, tcx).ty,
 246             &Operand::Constant(ref c) => c.literal.ty,
 247         }
 248     }
 249 }
 250
 251 impl<'tcx> BinOp {
 252     pub fn ty(&self, tcx: TyCtxt<'tcx>, lhs_ty: Ty<'tcx>, rhs_ty: Ty<'tcx>) -> Ty<'tcx> {
 253         // FIXME: handle SIMD correctly
 254         match self {
 255             &BinOp::Add | &BinOp::Sub | &BinOp::Mul | &BinOp::Div | &BinOp::Rem |
 256             &BinOp::BitXor | &BinOp::BitAnd | &BinOp::BitOr => {
 257                 // these should be integers or floats of the same size.
 258                 assert_eq!(lhs_ty, rhs_ty);
 259                 lhs_ty
 260             }
 261             &BinOp::Shl | &BinOp::Shr | &BinOp::Offset => {
 262                 lhs_ty // lhs_ty can be != rhs_ty
 263             }
 264             &BinOp::Eq | &BinOp::Lt | &BinOp::Le |
 265             &BinOp::Ne | &BinOp::Ge | &BinOp::Gt => {
 266                 tcx.types.bool
 267             }
 268         }
 269     }
 270 }
 271
 272 impl BorrowKind {
 273     pub fn to_mutbl_lossy(self) -> hir::Mutability {
 274         match self {
 275             BorrowKind::Mut { .. } => hir::Mutability::Mutable,
 276             BorrowKind::Shared => hir::Mutability::Immutable,
 277
 278             // We have no type corresponding to a unique imm borrow, so
 279             // use `&mut`. It gives all the capabilities of an `&uniq`
 280             // and hence is a safe "over approximation".
 281             BorrowKind::Unique => hir::Mutability::Mutable,
 282
 283             // We have no type corresponding to a shallow borrow, so use
 284             // `&` as an approximation.
 285             BorrowKind::Shallow => hir::Mutability::Immutable,
 286         }
 287     }
 288 }
 289
 290 impl BinOp {
 291     pub fn to_hir_binop(self) -> hir::BinOpKind {
 292         match self {
 293             BinOp::Add => hir::BinOpKind::Add,
 294             BinOp::Sub => hir::BinOpKind::Sub,
 295             BinOp::Mul => hir::BinOpKind::Mul,
 296             BinOp::Div => hir::BinOpKind::Div,
 297             BinOp::Rem => hir::BinOpKind::Rem,
 298             BinOp::BitXor => hir::BinOpKind::BitXor,
 299             BinOp::BitAnd => hir::BinOpKind::BitAnd,
 300             BinOp::BitOr => hir::BinOpKind::BitOr,
 301             BinOp::Shl => hir::BinOpKind::Shl,
 302             BinOp::Shr => hir::BinOpKind::Shr,
 303             BinOp::Eq => hir::BinOpKind::Eq,
 304             BinOp::Ne => hir::BinOpKind::Ne,
 305             BinOp::Lt => hir::BinOpKind::Lt,
 306             BinOp::Gt => hir::BinOpKind::Gt,
 307             BinOp::Le => hir::BinOpKind::Le,
 308             BinOp::Ge => hir::BinOpKind::Ge,
 309             BinOp::Offset => unreachable!()
 310         }
 311     }
 312 }