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