compiler/rustc_middle/src/ty/flags.rs

   1 use crate::ty::{self, InferConst, Ty, TypeFlags};
   2 use crate::ty::{GenericArg, GenericArgKind};
   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(_, args, _) => {
 109                 let args = args.as_generator();
 110                 let should_remove_further_specializable =
 111                     !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 112                 self.add_args(args.parent_args());
 113                 if should_remove_further_specializable {
 114                     self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
 115                 }
 116
 117                 self.add_ty(args.resume_ty());
 118                 self.add_ty(args.return_ty());
 119                 self.add_ty(args.witness());
 120                 self.add_ty(args.yield_ty());
 121                 self.add_ty(args.tupled_upvars_ty());
 122             }
 123
 124             &ty::GeneratorWitness(ts) => {
 125                 self.bound_computation(ts, |flags, ts| flags.add_tys(ts));
 126             }
 127
 128             ty::GeneratorWitnessMIR(_, args) => {
 129                 let should_remove_further_specializable =
 130                     !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 131                 self.add_args(args);
 132                 if should_remove_further_specializable {
 133                     self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
 134                 }
 135                 self.add_flags(TypeFlags::HAS_TY_GENERATOR);
 136             }
 137
 138             &ty::Closure(_, args) => {
 139                 let args = args.as_closure();
 140                 let should_remove_further_specializable =
 141                     !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 142                 self.add_args(args.parent_args());
 143                 if should_remove_further_specializable {
 144                     self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
 145                 }
 146
 147                 self.add_ty(args.sig_as_fn_ptr_ty());
 148                 self.add_ty(args.kind_ty());
 149                 self.add_ty(args.tupled_upvars_ty());
 150             }
 151
 152             &ty::Bound(debruijn, _) => {
 153                 self.add_bound_var(debruijn);
 154                 self.add_flags(TypeFlags::HAS_TY_LATE_BOUND);
 155             }
 156
 157             &ty::Placeholder(..) => {
 158                 self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER);
 159                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 160             }
 161
 162             &ty::Infer(infer) => {
 163                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 164                 match infer {
 165                     ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => {
 166                         self.add_flags(TypeFlags::HAS_TY_FRESH)
 167                     }
 168
 169                     ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => {
 170                         self.add_flags(TypeFlags::HAS_TY_INFER)
 171                     }
 172                 }
 173             }
 174
 175             &ty::Adt(_, args) => {
 176                 self.add_args(args);
 177             }
 178
 179             &ty::Alias(kind, data) => {
 180                 self.add_flags(match kind {
 181                     ty::Weak | ty::Projection => TypeFlags::HAS_TY_PROJECTION,
 182                     ty::Inherent => TypeFlags::HAS_TY_INHERENT,
 183                     ty::Opaque => TypeFlags::HAS_TY_OPAQUE,
 184                 });
 185
 186                 self.add_alias_ty(data);
 187             }
 188
 189             &ty::Dynamic(obj, r, _) => {
 190                 for predicate in obj.iter() {
 191                     self.bound_computation(predicate, |computation, predicate| match predicate {
 192                         ty::ExistentialPredicate::Trait(tr) => computation.add_args(tr.args),
 193                         ty::ExistentialPredicate::Projection(p) => {
 194                             computation.add_existential_projection(&p);
 195                         }
 196                         ty::ExistentialPredicate::AutoTrait(_) => {}
 197                     });
 198                 }
 199
 200                 self.add_region(r);
 201             }
 202
 203             &ty::Array(tt, len) => {
 204                 self.add_ty(tt);
 205                 self.add_const(len);
 206             }
 207
 208             &ty::Slice(tt) => self.add_ty(tt),
 209
 210             ty::RawPtr(m) => {
 211                 self.add_ty(m.ty);
 212             }
 213
 214             &ty::Ref(r, ty, _) => {
 215                 self.add_region(r);
 216                 self.add_ty(ty);
 217             }
 218
 219             &ty::Tuple(types) => {
 220                 self.add_tys(types);
 221             }
 222
 223             &ty::FnDef(_, args) => {
 224                 self.add_args(args);
 225             }
 226
 227             &ty::FnPtr(fn_sig) => self.bound_computation(fn_sig, |computation, fn_sig| {
 228                 computation.add_tys(fn_sig.inputs());
 229                 computation.add_ty(fn_sig.output());
 230             }),
 231         }
 232     }
 233
 234     fn add_predicate(&mut self, binder: ty::Binder<'_, ty::PredicateKind<'_>>) {
 235         self.bound_computation(binder, |computation, atom| computation.add_predicate_atom(atom));
 236     }
 237
 238     fn add_predicate_atom(&mut self, atom: ty::PredicateKind<'_>) {
 239         match atom {
 240             ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_pred)) => {
 241                 self.add_args(trait_pred.trait_ref.args);
 242             }
 243             ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(ty::OutlivesPredicate(
 244                 a,
 245                 b,
 246             ))) => {
 247                 self.add_region(a);
 248                 self.add_region(b);
 249             }
 250             ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(ty::OutlivesPredicate(
 251                 ty,
 252                 region,
 253             ))) => {
 254                 self.add_ty(ty);
 255                 self.add_region(region);
 256             }
 257             ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(ct, ty)) => {
 258                 self.add_const(ct);
 259                 self.add_ty(ty);
 260             }
 261             ty::PredicateKind::Subtype(ty::SubtypePredicate { a_is_expected: _, a, b }) => {
 262                 self.add_ty(a);
 263                 self.add_ty(b);
 264             }
 265             ty::PredicateKind::Coerce(ty::CoercePredicate { a, b }) => {
 266                 self.add_ty(a);
 267                 self.add_ty(b);
 268             }
 269             ty::PredicateKind::Clause(ty::ClauseKind::Projection(ty::ProjectionPredicate {
 270                 projection_ty,
 271                 term,
 272             })) => {
 273                 self.add_alias_ty(projection_ty);
 274                 self.add_term(term);
 275             }
 276             ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(arg)) => {
 277                 self.add_args(slice::from_ref(&arg));
 278             }
 279             ty::PredicateKind::ObjectSafe(_def_id) => {}
 280             ty::PredicateKind::ClosureKind(_def_id, args, _kind) => {
 281                 self.add_args(args);
 282             }
 283             ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(uv)) => {
 284                 self.add_const(uv);
 285             }
 286             ty::PredicateKind::ConstEquate(expected, found) => {
 287                 self.add_const(expected);
 288                 self.add_const(found);
 289             }
 290             ty::PredicateKind::Ambiguous => {}
 291             ty::PredicateKind::AliasRelate(t1, t2, _) => {
 292                 self.add_term(t1);
 293                 self.add_term(t2);
 294             }
 295         }
 296     }
 297
 298     fn add_ty(&mut self, ty: Ty<'_>) {
 299         self.add_flags(ty.flags());
 300         self.add_exclusive_binder(ty.outer_exclusive_binder());
 301     }
 302
 303     fn add_tys(&mut self, tys: &[Ty<'_>]) {
 304         for &ty in tys {
 305             self.add_ty(ty);
 306         }
 307     }
 308
 309     fn add_region(&mut self, r: ty::Region<'_>) {
 310         self.add_flags(r.type_flags());
 311         if let ty::ReLateBound(debruijn, _) = *r {
 312             self.add_bound_var(debruijn);
 313         }
 314     }
 315
 316     fn add_const(&mut self, c: ty::Const<'_>) {
 317         self.add_ty(c.ty());
 318         match c.kind() {
 319             ty::ConstKind::Unevaluated(uv) => {
 320                 self.add_args(uv.args);
 321                 self.add_flags(TypeFlags::HAS_CT_PROJECTION);
 322             }
 323             ty::ConstKind::Infer(infer) => {
 324                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 325                 match infer {
 326                     InferConst::Fresh(_) => self.add_flags(TypeFlags::HAS_CT_FRESH),
 327                     InferConst::Var(_) => self.add_flags(TypeFlags::HAS_CT_INFER),
 328                 }
 329             }
 330             ty::ConstKind::Bound(debruijn, _) => {
 331                 self.add_bound_var(debruijn);
 332                 self.add_flags(TypeFlags::HAS_CT_LATE_BOUND);
 333             }
 334             ty::ConstKind::Param(_) => {
 335                 self.add_flags(TypeFlags::HAS_CT_PARAM);
 336                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 337             }
 338             ty::ConstKind::Placeholder(_) => {
 339                 self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER);
 340                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 341             }
 342             ty::ConstKind::Value(_) => {}
 343             ty::ConstKind::Expr(e) => {
 344                 use ty::Expr;
 345                 match e {
 346                     Expr::Binop(_, l, r) => {
 347                         self.add_const(l);
 348                         self.add_const(r);
 349                     }
 350                     Expr::UnOp(_, v) => self.add_const(v),
 351                     Expr::FunctionCall(f, args) => {
 352                         self.add_const(f);
 353                         for arg in args {
 354                             self.add_const(arg);
 355                         }
 356                     }
 357                     Expr::Cast(_, c, t) => {
 358                         self.add_ty(t);
 359                         self.add_const(c);
 360                     }
 361                 }
 362             }
 363             ty::ConstKind::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
 364         }
 365     }
 366
 367     fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) {
 368         self.add_args(projection.args);
 369         match projection.term.unpack() {
 370             ty::TermKind::Ty(ty) => self.add_ty(ty),
 371             ty::TermKind::Const(ct) => self.add_const(ct),
 372         }
 373     }
 374
 375     fn add_alias_ty(&mut self, alias_ty: ty::AliasTy<'_>) {
 376         self.add_args(alias_ty.args);
 377     }
 378
 379     fn add_args(&mut self, args: &[GenericArg<'_>]) {
 380         for kind in args {
 381             match kind.unpack() {
 382                 GenericArgKind::Type(ty) => self.add_ty(ty),
 383                 GenericArgKind::Lifetime(lt) => self.add_region(lt),
 384                 GenericArgKind::Const(ct) => self.add_const(ct),
 385             }
 386         }
 387     }
 388
 389     fn add_term(&mut self, term: ty::Term<'_>) {
 390         match term.unpack() {
 391             ty::TermKind::Ty(ty) => self.add_ty(ty),
 392             ty::TermKind::Const(ct) => self.add_const(ct),
 393         }
 394     }
 395 }