diff options
Diffstat (limited to 'compiler/rustc_middle/src/ty/flags.rs')
| -rw-r--r-- | compiler/rustc_middle/src/ty/flags.rs | 330 |
1 files changed, 330 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/ty/flags.rs b/compiler/rustc_middle/src/ty/flags.rs new file mode 100644 index 00000000000..27f50c240db --- /dev/null +++ b/compiler/rustc_middle/src/ty/flags.rs @@ -0,0 +1,330 @@ +use crate::ty::subst::{GenericArg, GenericArgKind}; +use crate::ty::{self, InferConst, Ty, TypeFlags}; +use std::slice; + +#[derive(Debug)] +pub struct FlagComputation { + pub flags: TypeFlags, + + // see `TyS::outer_exclusive_binder` for details + pub outer_exclusive_binder: ty::DebruijnIndex, +} + +impl FlagComputation { + fn new() -> FlagComputation { + FlagComputation { flags: TypeFlags::empty(), outer_exclusive_binder: ty::INNERMOST } + } + + #[allow(rustc::usage_of_ty_tykind)] + pub fn for_kind(kind: &ty::TyKind<'_>) -> FlagComputation { + let mut result = FlagComputation::new(); + result.add_kind(kind); + result + } + + pub fn for_predicate(kind: &ty::PredicateKind<'_>) -> FlagComputation { + let mut result = FlagComputation::new(); + result.add_predicate_kind(kind); + result + } + + pub fn for_const(c: &ty::Const<'_>) -> TypeFlags { + let mut result = FlagComputation::new(); + result.add_const(c); + result.flags + } + + fn add_flags(&mut self, flags: TypeFlags) { + self.flags = self.flags | flags; + } + + /// indicates that `self` refers to something at binding level `binder` + fn add_bound_var(&mut self, binder: ty::DebruijnIndex) { + let exclusive_binder = binder.shifted_in(1); + self.add_exclusive_binder(exclusive_binder); + } + + /// indicates that `self` refers to something *inside* binding + /// level `binder` -- not bound by `binder`, but bound by the next + /// binder internal to it + fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) { + self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder); + } + + /// Adds the flags/depth from a set of types that appear within the current type, but within a + /// region binder. + fn add_bound_computation(&mut self, computation: FlagComputation) { + self.add_flags(computation.flags); + + // The types that contributed to `computation` occurred within + // a region binder, so subtract one from the region depth + // within when adding the depth to `self`. + let outer_exclusive_binder = computation.outer_exclusive_binder; + if outer_exclusive_binder > ty::INNERMOST { + self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1)); + } // otherwise, this binder captures nothing + } + + #[allow(rustc::usage_of_ty_tykind)] + fn add_kind(&mut self, kind: &ty::TyKind<'_>) { + match kind { + &ty::Bool + | &ty::Char + | &ty::Int(_) + | &ty::Float(_) + | &ty::Uint(_) + | &ty::Never + | &ty::Str + | &ty::Foreign(..) => {} + + &ty::Error(_) => self.add_flags(TypeFlags::HAS_ERROR), + + &ty::Param(_) => { + self.add_flags(TypeFlags::HAS_TY_PARAM); + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + } + + &ty::Generator(_, ref substs, _) => { + let substs = substs.as_generator(); + let should_remove_further_specializable = + !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + self.add_substs(substs.parent_substs()); + if should_remove_further_specializable { + self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE; + } + + self.add_ty(substs.resume_ty()); + self.add_ty(substs.return_ty()); + self.add_ty(substs.witness()); + self.add_ty(substs.yield_ty()); + self.add_ty(substs.tupled_upvars_ty()); + } + + &ty::GeneratorWitness(ts) => { + let mut computation = FlagComputation::new(); + computation.add_tys(ts.skip_binder()); + self.add_bound_computation(computation); + } + + &ty::Closure(_, substs) => { + let substs = substs.as_closure(); + let should_remove_further_specializable = + !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + self.add_substs(substs.parent_substs()); + if should_remove_further_specializable { + self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE; + } + + self.add_ty(substs.sig_as_fn_ptr_ty()); + self.add_ty(substs.kind_ty()); + self.add_ty(substs.tupled_upvars_ty()); + } + + &ty::Bound(debruijn, _) => { + self.add_bound_var(debruijn); + } + + &ty::Placeholder(..) => { + self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER); + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + } + + &ty::Infer(infer) => { + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + match infer { + ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => {} + + ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => { + self.add_flags(TypeFlags::HAS_TY_INFER) + } + } + } + + &ty::Adt(_, substs) => { + self.add_substs(substs); + } + + &ty::Projection(data) => { + self.add_flags(TypeFlags::HAS_TY_PROJECTION); + self.add_projection_ty(data); + } + + &ty::Opaque(_, substs) => { + self.add_flags(TypeFlags::HAS_TY_OPAQUE); + self.add_substs(substs); + } + + &ty::Dynamic(ref obj, r) => { + let mut computation = FlagComputation::new(); + for predicate in obj.skip_binder().iter() { + match predicate { + ty::ExistentialPredicate::Trait(tr) => computation.add_substs(tr.substs), + ty::ExistentialPredicate::Projection(p) => { + let mut proj_computation = FlagComputation::new(); + proj_computation.add_existential_projection(&p); + self.add_bound_computation(proj_computation); + } + ty::ExistentialPredicate::AutoTrait(_) => {} + } + } + self.add_bound_computation(computation); + self.add_region(r); + } + + &ty::Array(tt, len) => { + self.add_ty(tt); + self.add_const(len); + } + + &ty::Slice(tt) => self.add_ty(tt), + + &ty::RawPtr(ref m) => { + self.add_ty(m.ty); + } + + &ty::Ref(r, ty, _) => { + self.add_region(r); + self.add_ty(ty); + } + + &ty::Tuple(ref substs) => { + self.add_substs(substs); + } + + &ty::FnDef(_, substs) => { + self.add_substs(substs); + } + + &ty::FnPtr(f) => { + self.add_fn_sig(f); + } + } + } + + fn add_predicate_kind(&mut self, kind: &ty::PredicateKind<'_>) { + match kind { + ty::PredicateKind::ForAll(binder) => { + let mut computation = FlagComputation::new(); + + computation.add_predicate_atom(binder.skip_binder()); + + self.add_bound_computation(computation); + } + &ty::PredicateKind::Atom(atom) => self.add_predicate_atom(atom), + } + } + + fn add_predicate_atom(&mut self, atom: ty::PredicateAtom<'_>) { + match atom { + ty::PredicateAtom::Trait(trait_pred, _constness) => { + self.add_substs(trait_pred.trait_ref.substs); + } + ty::PredicateAtom::RegionOutlives(ty::OutlivesPredicate(a, b)) => { + self.add_region(a); + self.add_region(b); + } + ty::PredicateAtom::TypeOutlives(ty::OutlivesPredicate(ty, region)) => { + self.add_ty(ty); + self.add_region(region); + } + ty::PredicateAtom::Subtype(ty::SubtypePredicate { a_is_expected: _, a, b }) => { + self.add_ty(a); + self.add_ty(b); + } + ty::PredicateAtom::Projection(ty::ProjectionPredicate { projection_ty, ty }) => { + self.add_projection_ty(projection_ty); + self.add_ty(ty); + } + ty::PredicateAtom::WellFormed(arg) => { + self.add_substs(slice::from_ref(&arg)); + } + ty::PredicateAtom::ObjectSafe(_def_id) => {} + ty::PredicateAtom::ClosureKind(_def_id, substs, _kind) => { + self.add_substs(substs); + } + ty::PredicateAtom::ConstEvaluatable(_def_id, substs) => { + self.add_substs(substs); + } + ty::PredicateAtom::ConstEquate(expected, found) => { + self.add_const(expected); + self.add_const(found); + } + } + } + + fn add_ty(&mut self, ty: Ty<'_>) { + self.add_flags(ty.flags); + self.add_exclusive_binder(ty.outer_exclusive_binder); + } + + fn add_tys(&mut self, tys: &[Ty<'_>]) { + for &ty in tys { + self.add_ty(ty); + } + } + + fn add_fn_sig(&mut self, fn_sig: ty::PolyFnSig<'_>) { + let mut computation = FlagComputation::new(); + + computation.add_tys(fn_sig.skip_binder().inputs()); + computation.add_ty(fn_sig.skip_binder().output()); + + self.add_bound_computation(computation); + } + + fn add_region(&mut self, r: ty::Region<'_>) { + self.add_flags(r.type_flags()); + if let ty::ReLateBound(debruijn, _) = *r { + self.add_bound_var(debruijn); + } + } + + fn add_const(&mut self, c: &ty::Const<'_>) { + self.add_ty(c.ty); + match c.val { + ty::ConstKind::Unevaluated(_, substs, _) => { + self.add_substs(substs); + self.add_flags(TypeFlags::HAS_CT_PROJECTION); + } + ty::ConstKind::Infer(infer) => { + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + match infer { + InferConst::Fresh(_) => {} + InferConst::Var(_) => self.add_flags(TypeFlags::HAS_CT_INFER), + } + } + ty::ConstKind::Bound(debruijn, _) => { + self.add_bound_var(debruijn); + } + ty::ConstKind::Param(_) => { + self.add_flags(TypeFlags::HAS_CT_PARAM); + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + } + ty::ConstKind::Placeholder(_) => { + self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER); + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + } + ty::ConstKind::Value(_) => {} + ty::ConstKind::Error(_) => self.add_flags(TypeFlags::HAS_ERROR), + } + } + + fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) { + self.add_substs(projection.substs); + self.add_ty(projection.ty); + } + + fn add_projection_ty(&mut self, projection_ty: ty::ProjectionTy<'_>) { + self.add_substs(projection_ty.substs); + } + + fn add_substs(&mut self, substs: &[GenericArg<'_>]) { + for kind in substs { + match kind.unpack() { + GenericArgKind::Type(ty) => self.add_ty(ty), + GenericArgKind::Lifetime(lt) => self.add_region(lt), + GenericArgKind::Const(ct) => self.add_const(ct), + } + } + } +} |