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)]
  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.sty {
  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, 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         elem: &ProjectionElem<V, T>,
  72         mut handle_field: impl FnMut(&Self, &Field, &T) -> Ty<'tcx>,
  73     ) -> PlaceTy<'tcx>
  74     where
  75         V: ::std::fmt::Debug,
  76         T: ::std::fmt::Debug,
  77     {
  78         let answer = match *elem {
  79             ProjectionElem::Deref => {
  80                 let ty = self.ty
  81                              .builtin_deref(true)
  82                              .unwrap_or_else(|| {
  83                                  bug!("deref projection of non-dereferencable ty {:?}", self)
  84                              })
  85                              .ty;
  86                 PlaceTy::from_ty(ty)
  87             }
  88             ProjectionElem::Index(_) | ProjectionElem::ConstantIndex { .. } =>
  89                 PlaceTy::from_ty(self.ty.builtin_index().unwrap()),
  90             ProjectionElem::Subslice { from, to } => {
  91                 PlaceTy::from_ty(match self.ty.sty {
  92                     ty::Array(inner, size) => {
  93                         let size = size.unwrap_usize(tcx);
  94                         let len = size - (from as u64) - (to as u64);
  95                         tcx.mk_array(inner, len)
  96                     }
  97                     ty::Slice(..) => self.ty,
  98                     _ => {
  99                         bug!("cannot subslice non-array type: `{:?}`", self)
 100                     }
 101                 })
 102             }
 103             ProjectionElem::Downcast(_name, index) =>
 104                 PlaceTy { ty: self.ty, variant_index: Some(index) },
 105             ProjectionElem::Field(ref f, ref fty) =>
 106                 PlaceTy::from_ty(handle_field(&self, f, fty)),
 107         };
 108         debug!("projection_ty self: {:?} elem: {:?} yields: {:?}", self, elem, answer);
 109         answer
 110     }
 111 }
 112
 113 BraceStructTypeFoldableImpl! {
 114     impl<'tcx> TypeFoldable<'tcx> for PlaceTy<'tcx> {
 115         ty,
 116         variant_index,
 117     }
 118 }
 119
 120 impl<'tcx> Place<'tcx> {
 121     pub fn ty_from<D>(
 122         base: &PlaceBase<'tcx>,
 123         projection: &Option<Box<Projection<'tcx>>>,
 124         local_decls: &D,
 125         tcx: TyCtxt<'tcx>
 126     ) -> PlaceTy<'tcx>
 127         where D: HasLocalDecls<'tcx>
 128     {
 129         Place::iterate_over(base, projection, |place_base, place_projections| {
 130             let mut place_ty = place_base.ty(local_decls);
 131
 132             for proj in place_projections {
 133                 place_ty = place_ty.projection_ty(tcx, &proj.elem);
 134             }
 135
 136             place_ty
 137         })
 138     }
 139
 140     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> PlaceTy<'tcx>
 141     where
 142         D: HasLocalDecls<'tcx>,
 143     {
 144         Place::ty_from(&self.base, &self.projection, local_decls, tcx)
 145     }
 146 }
 147
 148 impl<'tcx> PlaceBase<'tcx> {
 149     pub fn ty<D>(&self, local_decls: &D) -> PlaceTy<'tcx>
 150         where D: HasLocalDecls<'tcx>
 151     {
 152         match self {
 153             PlaceBase::Local(index) => PlaceTy::from_ty(local_decls.local_decls()[*index].ty),
 154             PlaceBase::Static(data) => PlaceTy::from_ty(data.ty),
 155         }
 156     }
 157 }
 158
 159 pub enum RvalueInitializationState {
 160     Shallow,
 161     Deep
 162 }
 163
 164 impl<'tcx> Rvalue<'tcx> {
 165     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx>
 166     where
 167         D: HasLocalDecls<'tcx>,
 168     {
 169         match *self {
 170             Rvalue::Use(ref operand) => operand.ty(local_decls, tcx),
 171             Rvalue::Repeat(ref operand, count) => {
 172                 tcx.mk_array(operand.ty(local_decls, tcx), count)
 173             }
 174             Rvalue::Ref(reg, bk, ref place) => {
 175                 let place_ty = place.ty(local_decls, tcx).ty;
 176                 tcx.mk_ref(reg,
 177                     ty::TypeAndMut {
 178                         ty: place_ty,
 179                         mutbl: bk.to_mutbl_lossy()
 180                     }
 181                 )
 182             }
 183             Rvalue::Len(..) => tcx.types.usize,
 184             Rvalue::Cast(.., ty) => ty,
 185             Rvalue::BinaryOp(op, ref lhs, ref rhs) => {
 186                 let lhs_ty = lhs.ty(local_decls, tcx);
 187                 let rhs_ty = rhs.ty(local_decls, tcx);
 188                 op.ty(tcx, lhs_ty, rhs_ty)
 189             }
 190             Rvalue::CheckedBinaryOp(op, ref lhs, ref rhs) => {
 191                 let lhs_ty = lhs.ty(local_decls, tcx);
 192                 let rhs_ty = rhs.ty(local_decls, tcx);
 193                 let ty = op.ty(tcx, lhs_ty, rhs_ty);
 194                 tcx.intern_tup(&[ty, tcx.types.bool])
 195             }
 196             Rvalue::UnaryOp(UnOp::Not, ref operand) |
 197             Rvalue::UnaryOp(UnOp::Neg, ref operand) => {
 198                 operand.ty(local_decls, tcx)
 199             }
 200             Rvalue::Discriminant(ref place) => {
 201                 let ty = place.ty(local_decls, tcx).ty;
 202                 match ty.sty {
 203                     ty::Adt(adt_def, _) => adt_def.repr.discr_type().to_ty(tcx),
 204                     ty::Generator(_, substs, _) => substs.discr_ty(tcx),
 205                     _ => {
 206                         // This can only be `0`, for now, so `u8` will suffice.
 207                         tcx.types.u8
 208                     }
 209                 }
 210             }
 211             Rvalue::NullaryOp(NullOp::Box, t) => tcx.mk_box(t),
 212             Rvalue::NullaryOp(NullOp::SizeOf, _) => tcx.types.usize,
 213             Rvalue::Aggregate(ref ak, ref ops) => {
 214                 match **ak {
 215                     AggregateKind::Array(ty) => {
 216                         tcx.mk_array(ty, ops.len() as u64)
 217                     }
 218                     AggregateKind::Tuple => {
 219                         tcx.mk_tup(ops.iter().map(|op| op.ty(local_decls, tcx)))
 220                     }
 221                     AggregateKind::Adt(def, _, substs, _, _) => {
 222                         tcx.type_of(def.did).subst(tcx, substs)
 223                     }
 224                     AggregateKind::Closure(did, substs) => {
 225                         tcx.mk_closure(did, substs)
 226                     }
 227                     AggregateKind::Generator(did, substs, movability) => {
 228                         tcx.mk_generator(did, substs, movability)
 229                     }
 230                 }
 231             }
 232         }
 233     }
 234
 235     #[inline]
 236     /// Returns `true` if this rvalue is deeply initialized (most rvalues) or
 237     /// whether its only shallowly initialized (`Rvalue::Box`).
 238     pub fn initialization_state(&self) -> RvalueInitializationState {
 239         match *self {
 240             Rvalue::NullaryOp(NullOp::Box, _) => RvalueInitializationState::Shallow,
 241             _ => RvalueInitializationState::Deep
 242         }
 243     }
 244 }
 245
 246 impl<'tcx> Operand<'tcx> {
 247     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx>
 248     where
 249         D: HasLocalDecls<'tcx>,
 250     {
 251         match self {
 252             &Operand::Copy(ref l) |
 253             &Operand::Move(ref l) => l.ty(local_decls, tcx).ty,
 254             &Operand::Constant(ref c) => c.ty,
 255         }
 256     }
 257 }
 258
 259 impl<'tcx> BinOp {
 260     pub fn ty(&self, tcx: TyCtxt<'tcx>, lhs_ty: Ty<'tcx>, rhs_ty: Ty<'tcx>) -> Ty<'tcx> {
 261         // FIXME: handle SIMD correctly
 262         match self {
 263             &BinOp::Add | &BinOp::Sub | &BinOp::Mul | &BinOp::Div | &BinOp::Rem |
 264             &BinOp::BitXor | &BinOp::BitAnd | &BinOp::BitOr => {
 265                 // these should be integers or floats of the same size.
 266                 assert_eq!(lhs_ty, rhs_ty);
 267                 lhs_ty
 268             }
 269             &BinOp::Shl | &BinOp::Shr | &BinOp::Offset => {
 270                 lhs_ty // lhs_ty can be != rhs_ty
 271             }
 272             &BinOp::Eq | &BinOp::Lt | &BinOp::Le |
 273             &BinOp::Ne | &BinOp::Ge | &BinOp::Gt => {
 274                 tcx.types.bool
 275             }
 276         }
 277     }
 278 }
 279
 280 impl BorrowKind {
 281     pub fn to_mutbl_lossy(self) -> hir::Mutability {
 282         match self {
 283             BorrowKind::Mut { .. } => hir::MutMutable,
 284             BorrowKind::Shared => hir::MutImmutable,
 285
 286             // We have no type corresponding to a unique imm borrow, so
 287             // use `&mut`. It gives all the capabilities of an `&uniq`
 288             // and hence is a safe "over approximation".
 289             BorrowKind::Unique => hir::MutMutable,
 290
 291             // We have no type corresponding to a shallow borrow, so use
 292             // `&` as an approximation.
 293             BorrowKind::Shallow => hir::MutImmutable,
 294         }
 295     }
 296 }
 297
 298 impl BinOp {
 299     pub fn to_hir_binop(self) -> hir::BinOpKind {
 300         match self {
 301             BinOp::Add => hir::BinOpKind::Add,
 302             BinOp::Sub => hir::BinOpKind::Sub,
 303             BinOp::Mul => hir::BinOpKind::Mul,
 304             BinOp::Div => hir::BinOpKind::Div,
 305             BinOp::Rem => hir::BinOpKind::Rem,
 306             BinOp::BitXor => hir::BinOpKind::BitXor,
 307             BinOp::BitAnd => hir::BinOpKind::BitAnd,
 308             BinOp::BitOr => hir::BinOpKind::BitOr,
 309             BinOp::Shl => hir::BinOpKind::Shl,
 310             BinOp::Shr => hir::BinOpKind::Shr,
 311             BinOp::Eq => hir::BinOpKind::Eq,
 312             BinOp::Ne => hir::BinOpKind::Ne,
 313             BinOp::Lt => hir::BinOpKind::Lt,
 314             BinOp::Gt => hir::BinOpKind::Gt,
 315             BinOp::Le => hir::BinOpKind::Le,
 316             BinOp::Ge => hir::BinOpKind::Ge,
 317             BinOp::Offset => unreachable!()
 318         }
 319     }
 320 }