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         if !value.bound_vars().is_empty() {
  63             computation.add_flags(TypeFlags::HAS_BINDER_VARS);
  64         }
  65
  66         f(&mut computation, value.skip_binder());
  67
  68         self.add_flags(computation.flags);
  69
  70         // The types that contributed to `computation` occurred within
  71         // a region binder, so subtract one from the region depth
  72         // within when adding the depth to `self`.
  73         let outer_exclusive_binder = computation.outer_exclusive_binder;
  74         if outer_exclusive_binder > ty::INNERMOST {
  75             self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1));
  76         } // otherwise, this binder captures nothing
  77     }
  78
  79     #[allow(rustc::usage_of_ty_tykind)]
  80     fn add_kind(&mut self, kind: &ty::TyKind<'_>) {
  81         match kind {
  82             &ty::Bool
  83             | &ty::Char
  84             | &ty::Int(_)
  85             | &ty::Float(_)
  86             | &ty::Uint(_)
  87             | &ty::Never
  88             | &ty::Str
  89             | &ty::Foreign(..) => {}
  90
  91             &ty::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
  92
  93             &ty::Param(_) => {
  94                 self.add_flags(TypeFlags::HAS_TY_PARAM);
  95                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
  96             }
  97
  98             ty::Generator(_, args, _) => {
  99                 let args = args.as_generator();
 100                 let should_remove_further_specializable =
 101                     !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 102                 self.add_args(args.parent_args());
 103                 if should_remove_further_specializable {
 104                     self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
 105                 }
 106
 107                 self.add_ty(args.resume_ty());
 108                 self.add_ty(args.return_ty());
 109                 self.add_ty(args.witness());
 110                 self.add_ty(args.yield_ty());
 111                 self.add_ty(args.tupled_upvars_ty());
 112             }
 113
 114             ty::GeneratorWitness(_, args) => {
 115                 let should_remove_further_specializable =
 116                     !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 117                 self.add_args(args);
 118                 if should_remove_further_specializable {
 119                     self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
 120                 }
 121                 self.add_flags(TypeFlags::HAS_TY_GENERATOR);
 122             }
 123
 124             &ty::Closure(_, args) => {
 125                 let args = args.as_closure();
 126                 let should_remove_further_specializable =
 127                     !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 128                 self.add_args(args.parent_args());
 129                 if should_remove_further_specializable {
 130                     self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
 131                 }
 132
 133                 self.add_ty(args.sig_as_fn_ptr_ty());
 134                 self.add_ty(args.kind_ty());
 135                 self.add_ty(args.tupled_upvars_ty());
 136             }
 137
 138             &ty::Bound(debruijn, _) => {
 139                 self.add_bound_var(debruijn);
 140                 self.add_flags(TypeFlags::HAS_TY_LATE_BOUND);
 141             }
 142
 143             &ty::Placeholder(..) => {
 144                 self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER);
 145                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 146             }
 147
 148             &ty::Infer(infer) => {
 149                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 150                 match infer {
 151                     ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => {
 152                         self.add_flags(TypeFlags::HAS_TY_FRESH)
 153                     }
 154
 155                     ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => {
 156                         self.add_flags(TypeFlags::HAS_TY_INFER)
 157                     }
 158                 }
 159             }
 160
 161             &ty::Adt(_, args) => {
 162                 self.add_args(args);
 163             }
 164
 165             &ty::Alias(kind, data) => {
 166                 self.add_flags(match kind {
 167                     ty::Weak | ty::Projection => TypeFlags::HAS_TY_PROJECTION,
 168                     ty::Inherent => TypeFlags::HAS_TY_INHERENT,
 169                     ty::Opaque => TypeFlags::HAS_TY_OPAQUE,
 170                 });
 171
 172                 self.add_alias_ty(data);
 173             }
 174
 175             &ty::Dynamic(obj, r, _) => {
 176                 for predicate in obj.iter() {
 177                     self.bound_computation(predicate, |computation, predicate| match predicate {
 178                         ty::ExistentialPredicate::Trait(tr) => computation.add_args(tr.args),
 179                         ty::ExistentialPredicate::Projection(p) => {
 180                             computation.add_existential_projection(&p);
 181                         }
 182                         ty::ExistentialPredicate::AutoTrait(_) => {}
 183                     });
 184                 }
 185
 186                 self.add_region(r);
 187             }
 188
 189             &ty::Array(tt, len) => {
 190                 self.add_ty(tt);
 191                 self.add_const(len);
 192             }
 193
 194             &ty::Slice(tt) => self.add_ty(tt),
 195
 196             ty::RawPtr(m) => {
 197                 self.add_ty(m.ty);
 198             }
 199
 200             &ty::Ref(r, ty, _) => {
 201                 self.add_region(r);
 202                 self.add_ty(ty);
 203             }
 204
 205             &ty::Tuple(types) => {
 206                 self.add_tys(types);
 207             }
 208
 209             &ty::FnDef(_, args) => {
 210                 self.add_args(args);
 211             }
 212
 213             &ty::FnPtr(fn_sig) => self.bound_computation(fn_sig, |computation, fn_sig| {
 214                 computation.add_tys(fn_sig.inputs());
 215                 computation.add_ty(fn_sig.output());
 216             }),
 217         }
 218     }
 219
 220     fn add_predicate(&mut self, binder: ty::Binder<'_, ty::PredicateKind<'_>>) {
 221         self.bound_computation(binder, |computation, atom| computation.add_predicate_atom(atom));
 222     }
 223
 224     fn add_predicate_atom(&mut self, atom: ty::PredicateKind<'_>) {
 225         match atom {
 226             ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_pred)) => {
 227                 self.add_args(trait_pred.trait_ref.args);
 228             }
 229             ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(ty::OutlivesPredicate(
 230                 a,
 231                 b,
 232             ))) => {
 233                 self.add_region(a);
 234                 self.add_region(b);
 235             }
 236             ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(ty::OutlivesPredicate(
 237                 ty,
 238                 region,
 239             ))) => {
 240                 self.add_ty(ty);
 241                 self.add_region(region);
 242             }
 243             ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(ct, ty)) => {
 244                 self.add_const(ct);
 245                 self.add_ty(ty);
 246             }
 247             ty::PredicateKind::Subtype(ty::SubtypePredicate { a_is_expected: _, a, b }) => {
 248                 self.add_ty(a);
 249                 self.add_ty(b);
 250             }
 251             ty::PredicateKind::Coerce(ty::CoercePredicate { a, b }) => {
 252                 self.add_ty(a);
 253                 self.add_ty(b);
 254             }
 255             ty::PredicateKind::Clause(ty::ClauseKind::Projection(ty::ProjectionPredicate {
 256                 projection_ty,
 257                 term,
 258             })) => {
 259                 self.add_alias_ty(projection_ty);
 260                 self.add_term(term);
 261             }
 262             ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(arg)) => {
 263                 self.add_args(slice::from_ref(&arg));
 264             }
 265             ty::PredicateKind::ObjectSafe(_def_id) => {}
 266             ty::PredicateKind::ClosureKind(_def_id, args, _kind) => {
 267                 self.add_args(args);
 268             }
 269             ty::PredicateKind::Clause(ty::ClauseKind::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::Ambiguous => {}
 277             ty::PredicateKind::AliasRelate(t1, t2, _) => {
 278                 self.add_term(t1);
 279                 self.add_term(t2);
 280             }
 281         }
 282     }
 283
 284     fn add_ty(&mut self, ty: Ty<'_>) {
 285         self.add_flags(ty.flags());
 286         self.add_exclusive_binder(ty.outer_exclusive_binder());
 287     }
 288
 289     fn add_tys(&mut self, tys: &[Ty<'_>]) {
 290         for &ty in tys {
 291             self.add_ty(ty);
 292         }
 293     }
 294
 295     fn add_region(&mut self, r: ty::Region<'_>) {
 296         self.add_flags(r.type_flags());
 297         if let ty::ReLateBound(debruijn, _) = *r {
 298             self.add_bound_var(debruijn);
 299         }
 300     }
 301
 302     fn add_const(&mut self, c: ty::Const<'_>) {
 303         self.add_ty(c.ty());
 304         match c.kind() {
 305             ty::ConstKind::Unevaluated(uv) => {
 306                 self.add_args(uv.args);
 307                 self.add_flags(TypeFlags::HAS_CT_PROJECTION);
 308             }
 309             ty::ConstKind::Infer(infer) => {
 310                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 311                 match infer {
 312                     InferConst::Fresh(_) => self.add_flags(TypeFlags::HAS_CT_FRESH),
 313                     InferConst::Var(_) | InferConst::EffectVar(_) => {
 314                         self.add_flags(TypeFlags::HAS_CT_INFER)
 315                     }
 316                 }
 317             }
 318             ty::ConstKind::Bound(debruijn, _) => {
 319                 self.add_bound_var(debruijn);
 320                 self.add_flags(TypeFlags::HAS_CT_LATE_BOUND);
 321             }
 322             ty::ConstKind::Param(_) => {
 323                 self.add_flags(TypeFlags::HAS_CT_PARAM);
 324                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 325             }
 326             ty::ConstKind::Placeholder(_) => {
 327                 self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER);
 328                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
 329             }
 330             ty::ConstKind::Value(_) => {}
 331             ty::ConstKind::Expr(e) => {
 332                 use ty::Expr;
 333                 match e {
 334                     Expr::Binop(_, l, r) => {
 335                         self.add_const(l);
 336                         self.add_const(r);
 337                     }
 338                     Expr::UnOp(_, v) => self.add_const(v),
 339                     Expr::FunctionCall(f, args) => {
 340                         self.add_const(f);
 341                         for arg in args {
 342                             self.add_const(arg);
 343                         }
 344                     }
 345                     Expr::Cast(_, c, t) => {
 346                         self.add_ty(t);
 347                         self.add_const(c);
 348                     }
 349                 }
 350             }
 351             ty::ConstKind::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
 352         }
 353     }
 354
 355     fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) {
 356         self.add_args(projection.args);
 357         match projection.term.unpack() {
 358             ty::TermKind::Ty(ty) => self.add_ty(ty),
 359             ty::TermKind::Const(ct) => self.add_const(ct),
 360         }
 361     }
 362
 363     fn add_alias_ty(&mut self, alias_ty: ty::AliasTy<'_>) {
 364         self.add_args(alias_ty.args);
 365     }
 366
 367     fn add_args(&mut self, args: &[GenericArg<'_>]) {
 368         for kind in args {
 369             match kind.unpack() {
 370                 GenericArgKind::Type(ty) => self.add_ty(ty),
 371                 GenericArgKind::Lifetime(lt) => self.add_region(lt),
 372                 GenericArgKind::Const(ct) => self.add_const(ct),
 373             }
 374         }
 375     }
 376
 377     fn add_term(&mut self, term: ty::Term<'_>) {
 378         match term.unpack() {
 379             ty::TermKind::Ty(ty) => self.add_ty(ty),
 380             ty::TermKind::Const(ct) => self.add_const(ct),
 381         }
 382     }
 383 }