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