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::layout::VariantIdx;
   8 use crate::ty::subst::Subst;
   9 use crate::ty::util::IntTypeExt;
  10 use crate::ty::{self, Ty, TyCtxt};
  11 use rustc_hir as hir;
  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
  82                     .ty
  83                     .builtin_deref(true)
  84                     .unwrap_or_else(|| {
  85                         bug!("deref projection of non-dereferenceable ty {:?}", self)
  86                     })
  87                     .ty;
  88                 PlaceTy::from_ty(ty)
  89             }
  90             ProjectionElem::Index(_) | ProjectionElem::ConstantIndex { .. } => {
  91                 PlaceTy::from_ty(self.ty.builtin_index().unwrap())
  92             }
  93             ProjectionElem::Subslice { from, to, from_end } => {
  94                 PlaceTy::from_ty(match self.ty.kind {
  95                     ty::Slice(..) => self.ty,
  96                     ty::Array(inner, _) if !from_end => tcx.mk_array(inner, (to - from) as u64),
  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                     _ => bug!("cannot subslice non-array type: `{:?}`", self),
 103                 })
 104             }
 105             ProjectionElem::Downcast(_name, index) => {
 106                 PlaceTy { ty: self.ty, variant_index: Some(index) }
 107             }
 108             ProjectionElem::Field(ref f, ref fty) => PlaceTy::from_ty(handle_field(&self, f, fty)),
 109         };
 110         debug!("projection_ty self: {:?} elem: {:?} yields: {:?}", self, elem, answer);
 111         answer
 112     }
 113 }
 114
 115 impl<'tcx> Place<'tcx> {
 116     pub fn ty_from<D>(
 117         base: &PlaceBase,
 118         projection: &[PlaceElem<'tcx>],
 119         local_decls: &D,
 120         tcx: TyCtxt<'tcx>,
 121     ) -> PlaceTy<'tcx>
 122     where
 123         D: HasLocalDecls<'tcx>,
 124     {
 125         projection
 126             .iter()
 127             .fold(base.ty(local_decls), |place_ty, elem| place_ty.projection_ty(tcx, elem))
 128     }
 129
 130     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> PlaceTy<'tcx>
 131     where
 132         D: HasLocalDecls<'tcx>,
 133     {
 134         Place::ty_from(&self.base, &self.projection, local_decls, tcx)
 135     }
 136 }
 137
 138 impl<'tcx> PlaceBase {
 139     pub fn ty<D>(&self, local_decls: &D) -> PlaceTy<'tcx>
 140     where
 141         D: HasLocalDecls<'tcx>,
 142     {
 143         match self {
 144             PlaceBase::Local(index) => PlaceTy::from_ty(local_decls.local_decls()[*index].ty),
 145         }
 146     }
 147 }
 148
 149 pub enum RvalueInitializationState {
 150     Shallow,
 151     Deep,
 152 }
 153
 154 impl<'tcx> Rvalue<'tcx> {
 155     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx>
 156     where
 157         D: HasLocalDecls<'tcx>,
 158     {
 159         match *self {
 160             Rvalue::Use(ref operand) => operand.ty(local_decls, tcx),
 161             Rvalue::Repeat(ref operand, count) => tcx.mk_array(operand.ty(local_decls, tcx), count),
 162             Rvalue::Ref(reg, bk, ref place) => {
 163                 let place_ty = place.ty(local_decls, tcx).ty;
 164                 tcx.mk_ref(reg, ty::TypeAndMut { ty: place_ty, mutbl: bk.to_mutbl_lossy() })
 165             }
 166             Rvalue::AddressOf(mutability, ref place) => {
 167                 let place_ty = place.ty(local_decls, tcx).ty;
 168                 tcx.mk_ptr(ty::TypeAndMut { ty: place_ty, mutbl: mutability.into() })
 169             }
 170             Rvalue::Len(..) => tcx.types.usize,
 171             Rvalue::Cast(.., ty) => ty,
 172             Rvalue::BinaryOp(op, ref lhs, ref rhs) => {
 173                 let lhs_ty = lhs.ty(local_decls, tcx);
 174                 let rhs_ty = rhs.ty(local_decls, tcx);
 175                 op.ty(tcx, lhs_ty, rhs_ty)
 176             }
 177             Rvalue::CheckedBinaryOp(op, ref lhs, ref rhs) => {
 178                 let lhs_ty = lhs.ty(local_decls, tcx);
 179                 let rhs_ty = rhs.ty(local_decls, tcx);
 180                 let ty = op.ty(tcx, lhs_ty, rhs_ty);
 181                 tcx.intern_tup(&[ty, tcx.types.bool])
 182             }
 183             Rvalue::UnaryOp(UnOp::Not, ref operand) | Rvalue::UnaryOp(UnOp::Neg, ref operand) => {
 184                 operand.ty(local_decls, tcx)
 185             }
 186             Rvalue::Discriminant(ref place) => {
 187                 let ty = place.ty(local_decls, tcx).ty;
 188                 match ty.kind {
 189                     ty::Adt(adt_def, _) => adt_def.repr.discr_type().to_ty(tcx),
 190                     ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
 191                     _ => {
 192                         // This can only be `0`, for now, so `u8` will suffice.
 193                         tcx.types.u8
 194                     }
 195                 }
 196             }
 197             Rvalue::NullaryOp(NullOp::Box, t) => tcx.mk_box(t),
 198             Rvalue::NullaryOp(NullOp::SizeOf, _) => tcx.types.usize,
 199             Rvalue::Aggregate(ref ak, ref ops) => match **ak {
 200                 AggregateKind::Array(ty) => tcx.mk_array(ty, ops.len() as u64),
 201                 AggregateKind::Tuple => tcx.mk_tup(ops.iter().map(|op| op.ty(local_decls, tcx))),
 202                 AggregateKind::Adt(def, _, substs, _, _) => tcx.type_of(def.did).subst(tcx, substs),
 203                 AggregateKind::Closure(did, substs) => tcx.mk_closure(did, substs),
 204                 AggregateKind::Generator(did, substs, movability) => {
 205                     tcx.mk_generator(did, substs, movability)
 206                 }
 207             },
 208         }
 209     }
 210
 211     #[inline]
 212     /// Returns `true` if this rvalue is deeply initialized (most rvalues) or
 213     /// whether its only shallowly initialized (`Rvalue::Box`).
 214     pub fn initialization_state(&self) -> RvalueInitializationState {
 215         match *self {
 216             Rvalue::NullaryOp(NullOp::Box, _) => RvalueInitializationState::Shallow,
 217             _ => RvalueInitializationState::Deep,
 218         }
 219     }
 220 }
 221
 222 impl<'tcx> Operand<'tcx> {
 223     pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx>
 224     where
 225         D: HasLocalDecls<'tcx>,
 226     {
 227         match self {
 228             &Operand::Copy(ref l) | &Operand::Move(ref l) => l.ty(local_decls, tcx).ty,
 229             &Operand::Constant(ref c) => c.literal.ty,
 230         }
 231     }
 232 }
 233
 234 impl<'tcx> BinOp {
 235     pub fn ty(&self, tcx: TyCtxt<'tcx>, lhs_ty: Ty<'tcx>, rhs_ty: Ty<'tcx>) -> Ty<'tcx> {
 236         // FIXME: handle SIMD correctly
 237         match self {
 238             &BinOp::Add
 239             | &BinOp::Sub
 240             | &BinOp::Mul
 241             | &BinOp::Div
 242             | &BinOp::Rem
 243             | &BinOp::BitXor
 244             | &BinOp::BitAnd
 245             | &BinOp::BitOr => {
 246                 // these should be integers or floats of the same size.
 247                 assert_eq!(lhs_ty, rhs_ty);
 248                 lhs_ty
 249             }
 250             &BinOp::Shl | &BinOp::Shr | &BinOp::Offset => {
 251                 lhs_ty // lhs_ty can be != rhs_ty
 252             }
 253             &BinOp::Eq | &BinOp::Lt | &BinOp::Le | &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::Mutability::Mut,
 264             BorrowKind::Shared => hir::Mutability::Not,
 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::Mutability::Mut,
 270
 271             // We have no type corresponding to a shallow borrow, so use
 272             // `&` as an approximation.
 273             BorrowKind::Shallow => hir::Mutability::Not,
 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 }