compiler/rustc_middle/src/ty/flags.rs

   1 use crate::ty::subst::{GenericArg, GenericArgKind};
   2 use crate::ty::{self, InferConst, Ty, TypeFlags};
   3 use std::slice;
   4
   5 #[derive(Debug)]
   6 pub struct FlagComputation {
   7     pub flags: TypeFlags,
   8
   9     /// see `Ty::outer_exclusive_binder` for details
  10     pub outer_exclusive_binder: ty::DebruijnIndex,
  11 }
  12
  13 impl FlagComputation {
  14     fn new() -> FlagComputation {
  15         FlagComputation { flags: TypeFlags::empty(), outer_exclusive_binder: ty::INNERMOST }
  16     }
  17
  18     #[allow(rustc::usage_of_ty_tykind)]
  19     pub fn for_kind(kind: &ty::TyKind<'_>) -> FlagComputation {
  20         let mut result = FlagComputation::new();
  21         result.add_kind(kind);
  22         result
  23     }
  24
  25     pub fn for_predicate(binder: ty::Binder<'_, ty::PredicateKind<'_>>) -> FlagComputation {
  26         let mut result = FlagComputation::new();
  27         result.add_predicate(binder);
  28         result
  29     }
  30
  31     pub fn for_const(c: ty::Const<'_>) -> TypeFlags {
  32         let mut result = FlagComputation::new();
  33         result.add_const(c);
  34         result.flags
  35     }
  36
  37     fn add_flags(&mut self, flags: TypeFlags) {
  38         self.flags = self.flags | flags;
  39     }
  40
  41     /// indicates that `self` refers to something at binding level `binder`
  42     fn add_bound_var(&mut self, binder: ty::DebruijnIndex) {
  43         let exclusive_binder = binder.shifted_in(1);
  44         self.add_exclusive_binder(exclusive_binder);
  45     }
  46
  47     /// indicates that `self` refers to something *inside* binding
  48     /// level `binder` -- not bound by `binder`, but bound by the next
  49     /// binder internal to it
  50     fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) {
  51         self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder);
  52     }
  53
  54     /// Adds the flags/depth from a set of types that appear within the current type, but within a
  55     /// region binder.
  56     fn bound_computation<T, F>(&mut self, value: ty::Binder<'_, T>, f: F)
  57     where
  58         F: FnOnce(&mut Self, T),
  59     {
  60         let mut computation = FlagComputation::new();
  61
  62         for bv in value.bound_vars() {
  63             match bv {
  64                 ty::BoundVariableKind::Ty(_) => {
  65                     computation.flags |= TypeFlags::HAS_TY_LATE_BOUND;
  66                 }
  67                 ty::BoundVariableKind::Region(_) => {
  68                     computation.flags |= TypeFlags::HAS_RE_LATE_BOUND;
  69                 }
  70                 ty::BoundVariableKind::Const => {
  71                     computation.flags |= TypeFlags::HAS_CT_LATE_BOUND;
  72                 }
  73             }
  74         }
  75
  76         f(&mut computation, value.skip_binder());
  77
  78         self.add_flags(computation.flags);
  79
  80         // The types that contributed to `computation` occurred within
  81         // a region binder, so subtract one from the region depth
  82         // within when adding the depth to `self`.
  83         let outer_exclusive_binder = computation.outer_exclusive_binder;
  84         if outer_exclusive_binder > ty::INNERMOST {
  85             self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1));
  86         } // otherwise, this binder captures nothing
  87     }
  88
  89     #[allow(rustc::usage_of_ty_tykind)]
  90     fn add_kind(&mut self, kind: &ty::TyKind<'_>) {
  91         match kind {
  92             &ty::Bool
  93             | &ty::Char
  94             | &ty::Int(_)
  95             | &ty::Float(_)
  96             | &ty::Uint(_)
  97             | &ty::Never
  98             | &ty::Str
  99             | &ty::Foreign(..) => {}
 100
 101             &ty::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
 102
 103             &ty::Param(_) => {
 104                 self.add_flags(TypeFlags::HAS_TY_PARAM);
 105                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 106             }
 107
 108             ty::Generator(_, substs, _) => {
 109                 let substs = substs.as_generator();
 110                 let should_remove_further_specializable =
 111                     !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 112                 self.add_substs(substs.parent_substs());
 113                 if should_remove_further_specializable {
 114                     self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
 115                 }
 116
 117                 self.add_ty(substs.resume_ty());
 118                 self.add_ty(substs.return_ty());
 119                 self.add_ty(substs.witness());
 120                 self.add_ty(substs.yield_ty());
 121                 self.add_ty(substs.tupled_upvars_ty());
 122             }
 123
 124             &ty::GeneratorWitness(ts) => {
 125                 self.bound_computation(ts, |flags, ts| flags.add_tys(ts));
 126             }
 127
 128             &ty::Closure(_, substs) => {
 129                 let substs = substs.as_closure();
 130                 let should_remove_further_specializable =
 131                     !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 132                 self.add_substs(substs.parent_substs());
 133                 if should_remove_further_specializable {
 134                     self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
 135                 }
 136
 137                 self.add_ty(substs.sig_as_fn_ptr_ty());
 138                 self.add_ty(substs.kind_ty());
 139                 self.add_ty(substs.tupled_upvars_ty());
 140             }
 141
 142             &ty::Bound(debruijn, _) => {
 143                 self.add_bound_var(debruijn);
 144                 self.add_flags(TypeFlags::HAS_TY_LATE_BOUND);
 145             }
 146
 147             &ty::Placeholder(..) => {
 148                 self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER);
 149                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 150             }
 151
 152             &ty::Infer(infer) => {
 153                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 154                 match infer {
 155                     ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => {
 156                         self.add_flags(TypeFlags::HAS_TY_FRESH)
 157                     }
 158
 159                     ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => {
 160                         self.add_flags(TypeFlags::HAS_TY_INFER)
 161                     }
 162                 }
 163             }
 164
 165             &ty::Adt(_, substs) => {
 166                 self.add_substs(substs);
 167             }
 168
 169             &ty::Alias(ty::Projection, data) => {
 170                 self.add_flags(TypeFlags::HAS_TY_PROJECTION);
 171                 self.add_projection_ty(data);
 172             }
 173
 174             &ty::Alias(ty::Opaque, ty::AliasTy { substs, .. }) => {
 175                 self.add_flags(TypeFlags::HAS_TY_OPAQUE);
 176                 self.add_substs(substs);
 177             }
 178
 179             &ty::Dynamic(obj, r, _) => {
 180                 for predicate in obj.iter() {
 181                     self.bound_computation(predicate, |computation, predicate| match predicate {
 182                         ty::ExistentialPredicate::Trait(tr) => computation.add_substs(tr.substs),
 183                         ty::ExistentialPredicate::Projection(p) => {
 184                             computation.add_existential_projection(&p);
 185                         }
 186                         ty::ExistentialPredicate::AutoTrait(_) => {}
 187                     });
 188                 }
 189
 190                 self.add_region(r);
 191             }
 192
 193             &ty::Array(tt, len) => {
 194                 self.add_ty(tt);
 195                 self.add_const(len);
 196             }
 197
 198             &ty::Slice(tt) => self.add_ty(tt),
 199
 200             ty::RawPtr(m) => {
 201                 self.add_ty(m.ty);
 202             }
 203
 204             &ty::Ref(r, ty, _) => {
 205                 self.add_region(r);
 206                 self.add_ty(ty);
 207             }
 208
 209             &ty::Tuple(types) => {
 210                 self.add_tys(types);
 211             }
 212
 213             &ty::FnDef(_, substs) => {
 214                 self.add_substs(substs);
 215             }
 216
 217             &ty::FnPtr(fn_sig) => self.bound_computation(fn_sig, |computation, fn_sig| {
 218                 computation.add_tys(fn_sig.inputs());
 219                 computation.add_ty(fn_sig.output());
 220             }),
 221         }
 222     }
 223
 224     fn add_predicate(&mut self, binder: ty::Binder<'_, ty::PredicateKind<'_>>) {
 225         self.bound_computation(binder, |computation, atom| computation.add_predicate_atom(atom));
 226     }
 227
 228     fn add_predicate_atom(&mut self, atom: ty::PredicateKind<'_>) {
 229         match atom {
 230             ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred)) => {
 231                 self.add_substs(trait_pred.trait_ref.substs);
 232             }
 233             ty::PredicateKind::Clause(ty::Clause::RegionOutlives(ty::OutlivesPredicate(a, b))) => {
 234                 self.add_region(a);
 235                 self.add_region(b);
 236             }
 237             ty::PredicateKind::Clause(ty::Clause::TypeOutlives(ty::OutlivesPredicate(
 238                 ty,
 239                 region,
 240             ))) => {
 241                 self.add_ty(ty);
 242                 self.add_region(region);
 243             }
 244             ty::PredicateKind::Subtype(ty::SubtypePredicate { a_is_expected: _, a, b }) => {
 245                 self.add_ty(a);
 246                 self.add_ty(b);
 247             }
 248             ty::PredicateKind::Coerce(ty::CoercePredicate { a, b }) => {
 249                 self.add_ty(a);
 250                 self.add_ty(b);
 251             }
 252             ty::PredicateKind::Clause(ty::Clause::Projection(ty::ProjectionPredicate {
 253                 projection_ty,
 254                 term,
 255             })) => {
 256                 self.add_projection_ty(projection_ty);
 257                 match term.unpack() {
 258                     ty::TermKind::Ty(ty) => self.add_ty(ty),
 259                     ty::TermKind::Const(c) => self.add_const(c),
 260                 }
 261             }
 262             ty::PredicateKind::WellFormed(arg) => {
 263                 self.add_substs(slice::from_ref(&arg));
 264             }
 265             ty::PredicateKind::ObjectSafe(_def_id) => {}
 266             ty::PredicateKind::ClosureKind(_def_id, substs, _kind) => {
 267                 self.add_substs(substs);
 268             }
 269             ty::PredicateKind::ConstEvaluatable(uv) => {
 270                 self.add_const(uv);
 271             }
 272             ty::PredicateKind::ConstEquate(expected, found) => {
 273                 self.add_const(expected);
 274                 self.add_const(found);
 275             }
 276             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 277                 self.add_ty(ty);
 278             }
 279             ty::PredicateKind::Ambiguous => {}
 280         }
 281     }
 282
 283     fn add_ty(&mut self, ty: Ty<'_>) {
 284         self.add_flags(ty.flags());
 285         self.add_exclusive_binder(ty.outer_exclusive_binder());
 286     }
 287
 288     fn add_tys(&mut self, tys: &[Ty<'_>]) {
 289         for &ty in tys {
 290             self.add_ty(ty);
 291         }
 292     }
 293
 294     fn add_region(&mut self, r: ty::Region<'_>) {
 295         self.add_flags(r.type_flags());
 296         if let ty::ReLateBound(debruijn, _) = *r {
 297             self.add_bound_var(debruijn);
 298         }
 299     }
 300
 301     fn add_const(&mut self, c: ty::Const<'_>) {
 302         self.add_ty(c.ty());
 303         match c.kind() {
 304             ty::ConstKind::Unevaluated(uv) => {
 305                 self.add_substs(uv.substs);
 306                 self.add_flags(TypeFlags::HAS_CT_PROJECTION);
 307             }
 308             ty::ConstKind::Infer(infer) => {
 309                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 310                 match infer {
 311                     InferConst::Fresh(_) => self.add_flags(TypeFlags::HAS_CT_FRESH),
 312                     InferConst::Var(_) => self.add_flags(TypeFlags::HAS_CT_INFER),
 313                 }
 314             }
 315             ty::ConstKind::Bound(debruijn, _) => {
 316                 self.add_bound_var(debruijn);
 317                 self.add_flags(TypeFlags::HAS_CT_LATE_BOUND);
 318             }
 319             ty::ConstKind::Param(_) => {
 320                 self.add_flags(TypeFlags::HAS_CT_PARAM);
 321                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 322             }
 323             ty::ConstKind::Placeholder(_) => {
 324                 self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER);
 325                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 326             }
 327             ty::ConstKind::Value(_) => {}
 328             ty::ConstKind::Expr(e) => {
 329                 use ty::Expr;
 330                 match e {
 331                     Expr::Binop(_, l, r) => {
 332                         self.add_const(l);
 333                         self.add_const(r);
 334                     }
 335                     Expr::UnOp(_, v) => self.add_const(v),
 336                     Expr::FunctionCall(f, args) => {
 337                         self.add_const(f);
 338                         for arg in args {
 339                             self.add_const(arg);
 340                         }
 341                     }
 342                     Expr::Cast(_, c, t) => {
 343                         self.add_ty(t);
 344                         self.add_const(c);
 345                     }
 346                 }
 347             }
 348             ty::ConstKind::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
 349         }
 350     }
 351
 352     fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) {
 353         self.add_substs(projection.substs);
 354         match projection.term.unpack() {
 355             ty::TermKind::Ty(ty) => self.add_ty(ty),
 356             ty::TermKind::Const(ct) => self.add_const(ct),
 357         }
 358     }
 359
 360     fn add_projection_ty(&mut self, projection_ty: ty::AliasTy<'_>) {
 361         self.add_substs(projection_ty.substs);
 362     }
 363
 364     fn add_substs(&mut self, substs: &[GenericArg<'_>]) {
 365         for kind in substs {
 366             match kind.unpack() {
 367                 GenericArgKind::Type(ty) => self.add_ty(ty),
 368                 GenericArgKind::Lifetime(lt) => self.add_region(lt),
 369                 GenericArgKind::Const(ct) => self.add_const(ct),
 370             }
 371         }
 372     }
 373 }