| use hir::def_id::DefId; |
| use rustc_hir as hir; |
| use rustc_index::bit_set::BitSet; |
| use rustc_index::{IndexSlice, IndexVec}; |
| use rustc_middle::mir::{GeneratorLayout, GeneratorSavedLocal}; |
| use rustc_middle::query::Providers; |
| use rustc_middle::ty::layout::{ |
| IntegerExt, LayoutCx, LayoutError, LayoutOf, TyAndLayout, MAX_SIMD_LANES, |
| }; |
| use rustc_middle::ty::{ |
| self, subst::SubstsRef, AdtDef, EarlyBinder, ReprOptions, Ty, TyCtxt, TypeVisitableExt, |
| }; |
| use rustc_session::{DataTypeKind, FieldInfo, FieldKind, SizeKind, VariantInfo}; |
| use rustc_span::symbol::Symbol; |
| use rustc_span::DUMMY_SP; |
| use rustc_target::abi::*; |
| |
| use std::fmt::Debug; |
| use std::iter; |
| |
| use crate::errors::{ |
| MultipleArrayFieldsSimdType, NonPrimitiveSimdType, OversizedSimdType, ZeroLengthSimdType, |
| }; |
| use crate::layout_sanity_check::sanity_check_layout; |
| |
| pub fn provide(providers: &mut Providers) { |
| *providers = Providers { layout_of, ..*providers }; |
| } |
| |
| #[instrument(skip(tcx, query), level = "debug")] |
| fn layout_of<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, |
| ) -> Result<TyAndLayout<'tcx>, LayoutError<'tcx>> { |
| let (param_env, ty) = query.into_parts(); |
| debug!(?ty); |
| |
| let param_env = param_env.with_reveal_all_normalized(tcx); |
| let unnormalized_ty = ty; |
| |
| // FIXME: We might want to have two different versions of `layout_of`: |
| // One that can be called after typecheck has completed and can use |
| // `normalize_erasing_regions` here and another one that can be called |
| // before typecheck has completed and uses `try_normalize_erasing_regions`. |
| let ty = match tcx.try_normalize_erasing_regions(param_env, ty) { |
| Ok(t) => t, |
| Err(normalization_error) => { |
| return Err(LayoutError::NormalizationFailure(ty, normalization_error)); |
| } |
| }; |
| |
| if ty != unnormalized_ty { |
| // Ensure this layout is also cached for the normalized type. |
| return tcx.layout_of(param_env.and(ty)); |
| } |
| |
| let cx = LayoutCx { tcx, param_env }; |
| |
| let layout = layout_of_uncached(&cx, ty)?; |
| let layout = TyAndLayout { ty, layout }; |
| |
| record_layout_for_printing(&cx, layout); |
| |
| sanity_check_layout(&cx, &layout); |
| |
| Ok(layout) |
| } |
| |
| fn univariant_uninterned<'tcx>( |
| cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, |
| ty: Ty<'tcx>, |
| fields: &IndexSlice<FieldIdx, Layout<'_>>, |
| repr: &ReprOptions, |
| kind: StructKind, |
| ) -> Result<LayoutS, LayoutError<'tcx>> { |
| let dl = cx.data_layout(); |
| let pack = repr.pack; |
| if pack.is_some() && repr.align.is_some() { |
| cx.tcx.sess.delay_span_bug(DUMMY_SP, "struct cannot be packed and aligned"); |
| return Err(LayoutError::Unknown(ty)); |
| } |
| |
| cx.univariant(dl, fields, repr, kind).ok_or(LayoutError::SizeOverflow(ty)) |
| } |
| |
| fn layout_of_uncached<'tcx>( |
| cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, |
| ty: Ty<'tcx>, |
| ) -> Result<Layout<'tcx>, LayoutError<'tcx>> { |
| let tcx = cx.tcx; |
| let param_env = cx.param_env; |
| let dl = cx.data_layout(); |
| let scalar_unit = |value: Primitive| { |
| let size = value.size(dl); |
| assert!(size.bits() <= 128); |
| Scalar::Initialized { value, valid_range: WrappingRange::full(size) } |
| }; |
| let scalar = |value: Primitive| tcx.mk_layout(LayoutS::scalar(cx, scalar_unit(value))); |
| |
| let univariant = |fields: &IndexSlice<FieldIdx, Layout<'_>>, repr: &ReprOptions, kind| { |
| Ok(tcx.mk_layout(univariant_uninterned(cx, ty, fields, repr, kind)?)) |
| }; |
| debug_assert!(!ty.has_non_region_infer()); |
| |
| Ok(match *ty.kind() { |
| // Basic scalars. |
| ty::Bool => tcx.mk_layout(LayoutS::scalar( |
| cx, |
| Scalar::Initialized { |
| value: Int(I8, false), |
| valid_range: WrappingRange { start: 0, end: 1 }, |
| }, |
| )), |
| ty::Char => tcx.mk_layout(LayoutS::scalar( |
| cx, |
| Scalar::Initialized { |
| value: Int(I32, false), |
| valid_range: WrappingRange { start: 0, end: 0x10FFFF }, |
| }, |
| )), |
| ty::Int(ity) => scalar(Int(Integer::from_int_ty(dl, ity), true)), |
| ty::Uint(ity) => scalar(Int(Integer::from_uint_ty(dl, ity), false)), |
| ty::Float(fty) => scalar(match fty { |
| ty::FloatTy::F32 => F32, |
| ty::FloatTy::F64 => F64, |
| }), |
| ty::FnPtr(_) => { |
| let mut ptr = scalar_unit(Pointer(dl.instruction_address_space)); |
| ptr.valid_range_mut().start = 1; |
| tcx.mk_layout(LayoutS::scalar(cx, ptr)) |
| } |
| |
| // The never type. |
| ty::Never => tcx.mk_layout(cx.layout_of_never_type()), |
| |
| // Potentially-wide pointers. |
| ty::Ref(_, pointee, _) | ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => { |
| let mut data_ptr = scalar_unit(Pointer(AddressSpace::DATA)); |
| if !ty.is_unsafe_ptr() { |
| data_ptr.valid_range_mut().start = 1; |
| } |
| |
| let pointee = tcx.normalize_erasing_regions(param_env, pointee); |
| if pointee.is_sized(tcx, param_env) { |
| return Ok(tcx.mk_layout(LayoutS::scalar(cx, data_ptr))); |
| } |
| |
| let unsized_part = tcx.struct_tail_erasing_lifetimes(pointee, param_env); |
| |
| let metadata = if let Some(metadata_def_id) = tcx.lang_items().metadata_type() |
| // Projection eagerly bails out when the pointee references errors, |
| // fall back to structurally deducing metadata. |
| && !pointee.references_error() |
| { |
| let metadata_ty = tcx.normalize_erasing_regions( |
| param_env, |
| tcx.mk_projection(metadata_def_id, [pointee]), |
| ); |
| let metadata_layout = cx.layout_of(metadata_ty)?; |
| // If the metadata is a 1-zst, then the pointer is thin. |
| if metadata_layout.is_zst() && metadata_layout.align.abi.bytes() == 1 { |
| return Ok(tcx.mk_layout(LayoutS::scalar(cx, data_ptr))); |
| } |
| |
| let Abi::Scalar(metadata) = metadata_layout.abi else { |
| return Err(LayoutError::Unknown(unsized_part)); |
| }; |
| metadata |
| } else { |
| match unsized_part.kind() { |
| ty::Foreign(..) => { |
| return Ok(tcx.mk_layout(LayoutS::scalar(cx, data_ptr))); |
| } |
| ty::Slice(_) | ty::Str => scalar_unit(Int(dl.ptr_sized_integer(), false)), |
| ty::Dynamic(..) => { |
| let mut vtable = scalar_unit(Pointer(AddressSpace::DATA)); |
| vtable.valid_range_mut().start = 1; |
| vtable |
| } |
| _ => { |
| return Err(LayoutError::Unknown(unsized_part)); |
| } |
| } |
| }; |
| |
| // Effectively a (ptr, meta) tuple. |
| tcx.mk_layout(cx.scalar_pair(data_ptr, metadata)) |
| } |
| |
| ty::Dynamic(_, _, ty::DynStar) => { |
| let mut data = scalar_unit(Pointer(AddressSpace::DATA)); |
| data.valid_range_mut().start = 0; |
| let mut vtable = scalar_unit(Pointer(AddressSpace::DATA)); |
| vtable.valid_range_mut().start = 1; |
| tcx.mk_layout(cx.scalar_pair(data, vtable)) |
| } |
| |
| // Arrays and slices. |
| ty::Array(element, mut count) => { |
| if count.has_projections() { |
| count = tcx.normalize_erasing_regions(param_env, count); |
| if count.has_projections() { |
| return Err(LayoutError::Unknown(ty)); |
| } |
| } |
| |
| let count = |
| count.try_eval_target_usize(tcx, param_env).ok_or(LayoutError::Unknown(ty))?; |
| let element = cx.layout_of(element)?; |
| let size = element.size.checked_mul(count, dl).ok_or(LayoutError::SizeOverflow(ty))?; |
| |
| let abi = if count != 0 && ty.is_privately_uninhabited(tcx, param_env) { |
| Abi::Uninhabited |
| } else { |
| Abi::Aggregate { sized: true } |
| }; |
| |
| let largest_niche = if count != 0 { element.largest_niche } else { None }; |
| |
| tcx.mk_layout(LayoutS { |
| variants: Variants::Single { index: FIRST_VARIANT }, |
| fields: FieldsShape::Array { stride: element.size, count }, |
| abi, |
| largest_niche, |
| align: element.align, |
| size, |
| }) |
| } |
| ty::Slice(element) => { |
| let element = cx.layout_of(element)?; |
| tcx.mk_layout(LayoutS { |
| variants: Variants::Single { index: FIRST_VARIANT }, |
| fields: FieldsShape::Array { stride: element.size, count: 0 }, |
| abi: Abi::Aggregate { sized: false }, |
| largest_niche: None, |
| align: element.align, |
| size: Size::ZERO, |
| }) |
| } |
| ty::Str => tcx.mk_layout(LayoutS { |
| variants: Variants::Single { index: FIRST_VARIANT }, |
| fields: FieldsShape::Array { stride: Size::from_bytes(1), count: 0 }, |
| abi: Abi::Aggregate { sized: false }, |
| largest_niche: None, |
| align: dl.i8_align, |
| size: Size::ZERO, |
| }), |
| |
| // Odd unit types. |
| ty::FnDef(..) => { |
| univariant(IndexSlice::empty(), &ReprOptions::default(), StructKind::AlwaysSized)? |
| } |
| ty::Dynamic(_, _, ty::Dyn) | ty::Foreign(..) => { |
| let mut unit = univariant_uninterned( |
| cx, |
| ty, |
| IndexSlice::empty(), |
| &ReprOptions::default(), |
| StructKind::AlwaysSized, |
| )?; |
| match unit.abi { |
| Abi::Aggregate { ref mut sized } => *sized = false, |
| _ => bug!(), |
| } |
| tcx.mk_layout(unit) |
| } |
| |
| ty::Generator(def_id, substs, _) => generator_layout(cx, ty, def_id, substs)?, |
| |
| ty::Closure(_, ref substs) => { |
| let tys = substs.as_closure().upvar_tys(); |
| univariant( |
| &tys.map(|ty| Ok(cx.layout_of(ty)?.layout)).try_collect::<IndexVec<_, _>>()?, |
| &ReprOptions::default(), |
| StructKind::AlwaysSized, |
| )? |
| } |
| |
| ty::Tuple(tys) => { |
| let kind = |
| if tys.len() == 0 { StructKind::AlwaysSized } else { StructKind::MaybeUnsized }; |
| |
| univariant( |
| &tys.iter().map(|k| Ok(cx.layout_of(k)?.layout)).try_collect::<IndexVec<_, _>>()?, |
| &ReprOptions::default(), |
| kind, |
| )? |
| } |
| |
| // SIMD vector types. |
| ty::Adt(def, substs) if def.repr().simd() => { |
| if !def.is_struct() { |
| // Should have yielded E0517 by now. |
| tcx.sess.delay_span_bug( |
| DUMMY_SP, |
| "#[repr(simd)] was applied to an ADT that is not a struct", |
| ); |
| return Err(LayoutError::Unknown(ty)); |
| } |
| |
| let fields = &def.non_enum_variant().fields; |
| |
| // Supported SIMD vectors are homogeneous ADTs with at least one field: |
| // |
| // * #[repr(simd)] struct S(T, T, T, T); |
| // * #[repr(simd)] struct S { x: T, y: T, z: T, w: T } |
| // * #[repr(simd)] struct S([T; 4]) |
| // |
| // where T is a primitive scalar (integer/float/pointer). |
| |
| // SIMD vectors with zero fields are not supported. |
| // (should be caught by typeck) |
| if fields.is_empty() { |
| tcx.sess.emit_fatal(ZeroLengthSimdType { ty }) |
| } |
| |
| // Type of the first ADT field: |
| let f0_ty = fields[FieldIdx::from_u32(0)].ty(tcx, substs); |
| |
| // Heterogeneous SIMD vectors are not supported: |
| // (should be caught by typeck) |
| for fi in fields { |
| if fi.ty(tcx, substs) != f0_ty { |
| tcx.sess.delay_span_bug( |
| DUMMY_SP, |
| "#[repr(simd)] was applied to an ADT with heterogeneous field type", |
| ); |
| return Err(LayoutError::Unknown(ty)); |
| } |
| } |
| |
| // The element type and number of elements of the SIMD vector |
| // are obtained from: |
| // |
| // * the element type and length of the single array field, if |
| // the first field is of array type, or |
| // |
| // * the homogeneous field type and the number of fields. |
| let (e_ty, e_len, is_array) = if let ty::Array(e_ty, _) = f0_ty.kind() { |
| // First ADT field is an array: |
| |
| // SIMD vectors with multiple array fields are not supported: |
| // Can't be caught by typeck with a generic simd type. |
| if def.non_enum_variant().fields.len() != 1 { |
| tcx.sess.emit_fatal(MultipleArrayFieldsSimdType { ty }); |
| } |
| |
| // Extract the number of elements from the layout of the array field: |
| let FieldsShape::Array { count, .. } = cx.layout_of(f0_ty)?.layout.fields() else { |
| return Err(LayoutError::Unknown(ty)); |
| }; |
| |
| (*e_ty, *count, true) |
| } else { |
| // First ADT field is not an array: |
| (f0_ty, def.non_enum_variant().fields.len() as _, false) |
| }; |
| |
| // SIMD vectors of zero length are not supported. |
| // Additionally, lengths are capped at 2^16 as a fixed maximum backends must |
| // support. |
| // |
| // Can't be caught in typeck if the array length is generic. |
| if e_len == 0 { |
| tcx.sess.emit_fatal(ZeroLengthSimdType { ty }); |
| } else if e_len > MAX_SIMD_LANES { |
| tcx.sess.emit_fatal(OversizedSimdType { ty, max_lanes: MAX_SIMD_LANES }); |
| } |
| |
| // Compute the ABI of the element type: |
| let e_ly = cx.layout_of(e_ty)?; |
| let Abi::Scalar(e_abi) = e_ly.abi else { |
| // This error isn't caught in typeck, e.g., if |
| // the element type of the vector is generic. |
| tcx.sess.emit_fatal(NonPrimitiveSimdType { ty, e_ty }); |
| }; |
| |
| // Compute the size and alignment of the vector: |
| let size = e_ly.size.checked_mul(e_len, dl).ok_or(LayoutError::SizeOverflow(ty))?; |
| let align = dl.vector_align(size); |
| let size = size.align_to(align.abi); |
| |
| // Compute the placement of the vector fields: |
| let fields = if is_array { |
| FieldsShape::Arbitrary { offsets: [Size::ZERO].into(), memory_index: [0].into() } |
| } else { |
| FieldsShape::Array { stride: e_ly.size, count: e_len } |
| }; |
| |
| tcx.mk_layout(LayoutS { |
| variants: Variants::Single { index: FIRST_VARIANT }, |
| fields, |
| abi: Abi::Vector { element: e_abi, count: e_len }, |
| largest_niche: e_ly.largest_niche, |
| size, |
| align, |
| }) |
| } |
| |
| // ADTs. |
| ty::Adt(def, substs) => { |
| // Cache the field layouts. |
| let variants = def |
| .variants() |
| .iter() |
| .map(|v| { |
| v.fields |
| .iter() |
| .map(|field| Ok(cx.layout_of(field.ty(tcx, substs))?.layout)) |
| .try_collect::<IndexVec<_, _>>() |
| }) |
| .try_collect::<IndexVec<VariantIdx, _>>()?; |
| |
| if def.is_union() { |
| if def.repr().pack.is_some() && def.repr().align.is_some() { |
| cx.tcx.sess.delay_span_bug( |
| tcx.def_span(def.did()), |
| "union cannot be packed and aligned", |
| ); |
| return Err(LayoutError::Unknown(ty)); |
| } |
| |
| return Ok(tcx.mk_layout( |
| cx.layout_of_union(&def.repr(), &variants).ok_or(LayoutError::Unknown(ty))?, |
| )); |
| } |
| |
| tcx.mk_layout( |
| cx.layout_of_struct_or_enum( |
| &def.repr(), |
| &variants, |
| def.is_enum(), |
| def.is_unsafe_cell(), |
| tcx.layout_scalar_valid_range(def.did()), |
| |min, max| Integer::repr_discr(tcx, ty, &def.repr(), min, max), |
| def.is_enum() |
| .then(|| def.discriminants(tcx).map(|(v, d)| (v, d.val as i128))) |
| .into_iter() |
| .flatten(), |
| def.repr().inhibit_enum_layout_opt() |
| || def |
| .variants() |
| .iter_enumerated() |
| .any(|(i, v)| v.discr != ty::VariantDiscr::Relative(i.as_u32())), |
| { |
| let param_env = tcx.param_env(def.did()); |
| def.is_struct() |
| && match def.variants().iter().next().and_then(|x| x.fields.raw.last()) |
| { |
| Some(last_field) => tcx |
| .type_of(last_field.did) |
| .subst_identity() |
| .is_sized(tcx, param_env), |
| None => false, |
| } |
| }, |
| ) |
| .ok_or(LayoutError::SizeOverflow(ty))?, |
| ) |
| } |
| |
| // Types with no meaningful known layout. |
| ty::Alias(..) => { |
| // NOTE(eddyb) `layout_of` query should've normalized these away, |
| // if that was possible, so there's no reason to try again here. |
| return Err(LayoutError::Unknown(ty)); |
| } |
| |
| ty::Bound(..) | ty::GeneratorWitness(..) | ty::GeneratorWitnessMIR(..) | ty::Infer(_) => { |
| bug!("Layout::compute: unexpected type `{}`", ty) |
| } |
| |
| ty::Placeholder(..) | ty::Param(_) | ty::Error(_) => { |
| return Err(LayoutError::Unknown(ty)); |
| } |
| }) |
| } |
| |
| /// Overlap eligibility and variant assignment for each GeneratorSavedLocal. |
| #[derive(Clone, Debug, PartialEq)] |
| enum SavedLocalEligibility { |
| Unassigned, |
| Assigned(VariantIdx), |
| Ineligible(Option<FieldIdx>), |
| } |
| |
| // When laying out generators, we divide our saved local fields into two |
| // categories: overlap-eligible and overlap-ineligible. |
| // |
| // Those fields which are ineligible for overlap go in a "prefix" at the |
| // beginning of the layout, and always have space reserved for them. |
| // |
| // Overlap-eligible fields are only assigned to one variant, so we lay |
| // those fields out for each variant and put them right after the |
| // prefix. |
| // |
| // Finally, in the layout details, we point to the fields from the |
| // variants they are assigned to. It is possible for some fields to be |
| // included in multiple variants. No field ever "moves around" in the |
| // layout; its offset is always the same. |
| // |
| // Also included in the layout are the upvars and the discriminant. |
| // These are included as fields on the "outer" layout; they are not part |
| // of any variant. |
| |
| /// Compute the eligibility and assignment of each local. |
| fn generator_saved_local_eligibility( |
| info: &GeneratorLayout<'_>, |
| ) -> (BitSet<GeneratorSavedLocal>, IndexVec<GeneratorSavedLocal, SavedLocalEligibility>) { |
| use SavedLocalEligibility::*; |
| |
| let mut assignments: IndexVec<GeneratorSavedLocal, SavedLocalEligibility> = |
| IndexVec::from_elem(Unassigned, &info.field_tys); |
| |
| // The saved locals not eligible for overlap. These will get |
| // "promoted" to the prefix of our generator. |
| let mut ineligible_locals = BitSet::new_empty(info.field_tys.len()); |
| |
| // Figure out which of our saved locals are fields in only |
| // one variant. The rest are deemed ineligible for overlap. |
| for (variant_index, fields) in info.variant_fields.iter_enumerated() { |
| for local in fields { |
| match assignments[*local] { |
| Unassigned => { |
| assignments[*local] = Assigned(variant_index); |
| } |
| Assigned(idx) => { |
| // We've already seen this local at another suspension |
| // point, so it is no longer a candidate. |
| trace!( |
| "removing local {:?} in >1 variant ({:?}, {:?})", |
| local, |
| variant_index, |
| idx |
| ); |
| ineligible_locals.insert(*local); |
| assignments[*local] = Ineligible(None); |
| } |
| Ineligible(_) => {} |
| } |
| } |
| } |
| |
| // Next, check every pair of eligible locals to see if they |
| // conflict. |
| for local_a in info.storage_conflicts.rows() { |
| let conflicts_a = info.storage_conflicts.count(local_a); |
| if ineligible_locals.contains(local_a) { |
| continue; |
| } |
| |
| for local_b in info.storage_conflicts.iter(local_a) { |
| // local_a and local_b are storage live at the same time, therefore they |
| // cannot overlap in the generator layout. The only way to guarantee |
| // this is if they are in the same variant, or one is ineligible |
| // (which means it is stored in every variant). |
| if ineligible_locals.contains(local_b) || assignments[local_a] == assignments[local_b] { |
| continue; |
| } |
| |
| // If they conflict, we will choose one to make ineligible. |
| // This is not always optimal; it's just a greedy heuristic that |
| // seems to produce good results most of the time. |
| let conflicts_b = info.storage_conflicts.count(local_b); |
| let (remove, other) = |
| if conflicts_a > conflicts_b { (local_a, local_b) } else { (local_b, local_a) }; |
| ineligible_locals.insert(remove); |
| assignments[remove] = Ineligible(None); |
| trace!("removing local {:?} due to conflict with {:?}", remove, other); |
| } |
| } |
| |
| // Count the number of variants in use. If only one of them, then it is |
| // impossible to overlap any locals in our layout. In this case it's |
| // always better to make the remaining locals ineligible, so we can |
| // lay them out with the other locals in the prefix and eliminate |
| // unnecessary padding bytes. |
| { |
| let mut used_variants = BitSet::new_empty(info.variant_fields.len()); |
| for assignment in &assignments { |
| if let Assigned(idx) = assignment { |
| used_variants.insert(*idx); |
| } |
| } |
| if used_variants.count() < 2 { |
| for assignment in assignments.iter_mut() { |
| *assignment = Ineligible(None); |
| } |
| ineligible_locals.insert_all(); |
| } |
| } |
| |
| // Write down the order of our locals that will be promoted to the prefix. |
| { |
| for (idx, local) in ineligible_locals.iter().enumerate() { |
| assignments[local] = Ineligible(Some(FieldIdx::from_usize(idx))); |
| } |
| } |
| debug!("generator saved local assignments: {:?}", assignments); |
| |
| (ineligible_locals, assignments) |
| } |
| |
| /// Compute the full generator layout. |
| fn generator_layout<'tcx>( |
| cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, |
| ty: Ty<'tcx>, |
| def_id: hir::def_id::DefId, |
| substs: SubstsRef<'tcx>, |
| ) -> Result<Layout<'tcx>, LayoutError<'tcx>> { |
| use SavedLocalEligibility::*; |
| let tcx = cx.tcx; |
| let subst_field = |ty: Ty<'tcx>| EarlyBinder::new(ty).subst(tcx, substs); |
| |
| let Some(info) = tcx.generator_layout(def_id) else { |
| return Err(LayoutError::Unknown(ty)); |
| }; |
| let (ineligible_locals, assignments) = generator_saved_local_eligibility(&info); |
| |
| // Build a prefix layout, including "promoting" all ineligible |
| // locals as part of the prefix. We compute the layout of all of |
| // these fields at once to get optimal packing. |
| let tag_index = substs.as_generator().prefix_tys().count(); |
| |
| // `info.variant_fields` already accounts for the reserved variants, so no need to add them. |
| let max_discr = (info.variant_fields.len() - 1) as u128; |
| let discr_int = Integer::fit_unsigned(max_discr); |
| let tag = Scalar::Initialized { |
| value: Primitive::Int(discr_int, false), |
| valid_range: WrappingRange { start: 0, end: max_discr }, |
| }; |
| let tag_layout = cx.tcx.mk_layout(LayoutS::scalar(cx, tag)); |
| |
| let promoted_layouts = ineligible_locals |
| .iter() |
| .map(|local| subst_field(info.field_tys[local].ty)) |
| .map(|ty| tcx.mk_maybe_uninit(ty)) |
| .map(|ty| Ok(cx.layout_of(ty)?.layout)); |
| let prefix_layouts = substs |
| .as_generator() |
| .prefix_tys() |
| .map(|ty| Ok(cx.layout_of(ty)?.layout)) |
| .chain(iter::once(Ok(tag_layout))) |
| .chain(promoted_layouts) |
| .try_collect::<IndexVec<_, _>>()?; |
| let prefix = univariant_uninterned( |
| cx, |
| ty, |
| &prefix_layouts, |
| &ReprOptions::default(), |
| StructKind::AlwaysSized, |
| )?; |
| |
| let (prefix_size, prefix_align) = (prefix.size, prefix.align); |
| |
| // Split the prefix layout into the "outer" fields (upvars and |
| // discriminant) and the "promoted" fields. Promoted fields will |
| // get included in each variant that requested them in |
| // GeneratorLayout. |
| debug!("prefix = {:#?}", prefix); |
| let (outer_fields, promoted_offsets, promoted_memory_index) = match prefix.fields { |
| FieldsShape::Arbitrary { mut offsets, memory_index } => { |
| let mut inverse_memory_index = memory_index.invert_bijective_mapping(); |
| |
| // "a" (`0..b_start`) and "b" (`b_start..`) correspond to |
| // "outer" and "promoted" fields respectively. |
| let b_start = FieldIdx::from_usize(tag_index + 1); |
| let offsets_b = IndexVec::from_raw(offsets.raw.split_off(b_start.as_usize())); |
| let offsets_a = offsets; |
| |
| // Disentangle the "a" and "b" components of `inverse_memory_index` |
| // by preserving the order but keeping only one disjoint "half" each. |
| // FIXME(eddyb) build a better abstraction for permutations, if possible. |
| let inverse_memory_index_b: IndexVec<u32, FieldIdx> = inverse_memory_index |
| .iter() |
| .filter_map(|&i| i.as_u32().checked_sub(b_start.as_u32()).map(FieldIdx::from_u32)) |
| .collect(); |
| inverse_memory_index.raw.retain(|&i| i < b_start); |
| let inverse_memory_index_a = inverse_memory_index; |
| |
| // Since `inverse_memory_index_{a,b}` each only refer to their |
| // respective fields, they can be safely inverted |
| let memory_index_a = inverse_memory_index_a.invert_bijective_mapping(); |
| let memory_index_b = inverse_memory_index_b.invert_bijective_mapping(); |
| |
| let outer_fields = |
| FieldsShape::Arbitrary { offsets: offsets_a, memory_index: memory_index_a }; |
| (outer_fields, offsets_b, memory_index_b) |
| } |
| _ => bug!(), |
| }; |
| |
| let mut size = prefix.size; |
| let mut align = prefix.align; |
| let variants = info |
| .variant_fields |
| .iter_enumerated() |
| .map(|(index, variant_fields)| { |
| // Only include overlap-eligible fields when we compute our variant layout. |
| let variant_only_tys = variant_fields |
| .iter() |
| .filter(|local| match assignments[**local] { |
| Unassigned => bug!(), |
| Assigned(v) if v == index => true, |
| Assigned(_) => bug!("assignment does not match variant"), |
| Ineligible(_) => false, |
| }) |
| .map(|local| subst_field(info.field_tys[*local].ty)); |
| |
| let mut variant = univariant_uninterned( |
| cx, |
| ty, |
| &variant_only_tys |
| .map(|ty| Ok(cx.layout_of(ty)?.layout)) |
| .try_collect::<IndexVec<_, _>>()?, |
| &ReprOptions::default(), |
| StructKind::Prefixed(prefix_size, prefix_align.abi), |
| )?; |
| variant.variants = Variants::Single { index }; |
| |
| let FieldsShape::Arbitrary { offsets, memory_index } = variant.fields else { |
| bug!(); |
| }; |
| |
| // Now, stitch the promoted and variant-only fields back together in |
| // the order they are mentioned by our GeneratorLayout. |
| // Because we only use some subset (that can differ between variants) |
| // of the promoted fields, we can't just pick those elements of the |
| // `promoted_memory_index` (as we'd end up with gaps). |
| // So instead, we build an "inverse memory_index", as if all of the |
| // promoted fields were being used, but leave the elements not in the |
| // subset as `INVALID_FIELD_IDX`, which we can filter out later to |
| // obtain a valid (bijective) mapping. |
| const INVALID_FIELD_IDX: FieldIdx = FieldIdx::MAX; |
| debug_assert!(variant_fields.next_index() <= INVALID_FIELD_IDX); |
| |
| let mut combined_inverse_memory_index = IndexVec::from_elem_n( |
| INVALID_FIELD_IDX, |
| promoted_memory_index.len() + memory_index.len(), |
| ); |
| let mut offsets_and_memory_index = iter::zip(offsets, memory_index); |
| let combined_offsets = variant_fields |
| .iter_enumerated() |
| .map(|(i, local)| { |
| let (offset, memory_index) = match assignments[*local] { |
| Unassigned => bug!(), |
| Assigned(_) => { |
| let (offset, memory_index) = offsets_and_memory_index.next().unwrap(); |
| (offset, promoted_memory_index.len() as u32 + memory_index) |
| } |
| Ineligible(field_idx) => { |
| let field_idx = field_idx.unwrap(); |
| (promoted_offsets[field_idx], promoted_memory_index[field_idx]) |
| } |
| }; |
| combined_inverse_memory_index[memory_index] = i; |
| offset |
| }) |
| .collect(); |
| |
| // Remove the unused slots and invert the mapping to obtain the |
| // combined `memory_index` (also see previous comment). |
| combined_inverse_memory_index.raw.retain(|&i| i != INVALID_FIELD_IDX); |
| let combined_memory_index = combined_inverse_memory_index.invert_bijective_mapping(); |
| |
| variant.fields = FieldsShape::Arbitrary { |
| offsets: combined_offsets, |
| memory_index: combined_memory_index, |
| }; |
| |
| size = size.max(variant.size); |
| align = align.max(variant.align); |
| Ok(variant) |
| }) |
| .try_collect::<IndexVec<VariantIdx, _>>()?; |
| |
| size = size.align_to(align.abi); |
| |
| let abi = if prefix.abi.is_uninhabited() || variants.iter().all(|v| v.abi.is_uninhabited()) { |
| Abi::Uninhabited |
| } else { |
| Abi::Aggregate { sized: true } |
| }; |
| |
| let layout = tcx.mk_layout(LayoutS { |
| variants: Variants::Multiple { |
| tag, |
| tag_encoding: TagEncoding::Direct, |
| tag_field: tag_index, |
| variants, |
| }, |
| fields: outer_fields, |
| abi, |
| largest_niche: prefix.largest_niche, |
| size, |
| align, |
| }); |
| debug!("generator layout ({:?}): {:#?}", ty, layout); |
| Ok(layout) |
| } |
| |
| /// This is invoked by the `layout_of` query to record the final |
| /// layout of each type. |
| #[inline(always)] |
| fn record_layout_for_printing<'tcx>(cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, layout: TyAndLayout<'tcx>) { |
| // If we are running with `-Zprint-type-sizes`, maybe record layouts |
| // for dumping later. |
| if cx.tcx.sess.opts.unstable_opts.print_type_sizes { |
| record_layout_for_printing_outlined(cx, layout) |
| } |
| } |
| |
| fn record_layout_for_printing_outlined<'tcx>( |
| cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, |
| layout: TyAndLayout<'tcx>, |
| ) { |
| // Ignore layouts that are done with non-empty environments or |
| // non-monomorphic layouts, as the user only wants to see the stuff |
| // resulting from the final codegen session. |
| if layout.ty.has_non_region_param() || !cx.param_env.caller_bounds().is_empty() { |
| return; |
| } |
| |
| // (delay format until we actually need it) |
| let record = |kind, packed, opt_discr_size, variants| { |
| let type_desc = format!("{:?}", layout.ty); |
| cx.tcx.sess.code_stats.record_type_size( |
| kind, |
| type_desc, |
| layout.align.abi, |
| layout.size, |
| packed, |
| opt_discr_size, |
| variants, |
| ); |
| }; |
| |
| match *layout.ty.kind() { |
| ty::Adt(adt_def, _) => { |
| debug!("print-type-size t: `{:?}` process adt", layout.ty); |
| let adt_kind = adt_def.adt_kind(); |
| let adt_packed = adt_def.repr().pack.is_some(); |
| let (variant_infos, opt_discr_size) = variant_info_for_adt(cx, layout, adt_def); |
| record(adt_kind.into(), adt_packed, opt_discr_size, variant_infos); |
| } |
| |
| ty::Generator(def_id, substs, _) => { |
| debug!("print-type-size t: `{:?}` record generator", layout.ty); |
| // Generators always have a begin/poisoned/end state with additional suspend points |
| let (variant_infos, opt_discr_size) = |
| variant_info_for_generator(cx, layout, def_id, substs); |
| record(DataTypeKind::Generator, false, opt_discr_size, variant_infos); |
| } |
| |
| ty::Closure(..) => { |
| debug!("print-type-size t: `{:?}` record closure", layout.ty); |
| record(DataTypeKind::Closure, false, None, vec![]); |
| } |
| |
| _ => { |
| debug!("print-type-size t: `{:?}` skip non-nominal", layout.ty); |
| } |
| }; |
| } |
| |
| fn variant_info_for_adt<'tcx>( |
| cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, |
| layout: TyAndLayout<'tcx>, |
| adt_def: AdtDef<'tcx>, |
| ) -> (Vec<VariantInfo>, Option<Size>) { |
| let build_variant_info = |n: Option<Symbol>, flds: &[Symbol], layout: TyAndLayout<'tcx>| { |
| let mut min_size = Size::ZERO; |
| let field_info: Vec<_> = flds |
| .iter() |
| .enumerate() |
| .map(|(i, &name)| { |
| let field_layout = layout.field(cx, i); |
| let offset = layout.fields.offset(i); |
| min_size = min_size.max(offset + field_layout.size); |
| FieldInfo { |
| kind: FieldKind::AdtField, |
| name, |
| offset: offset.bytes(), |
| size: field_layout.size.bytes(), |
| align: field_layout.align.abi.bytes(), |
| } |
| }) |
| .collect(); |
| |
| VariantInfo { |
| name: n, |
| kind: if layout.is_unsized() { SizeKind::Min } else { SizeKind::Exact }, |
| align: layout.align.abi.bytes(), |
| size: if min_size.bytes() == 0 { layout.size.bytes() } else { min_size.bytes() }, |
| fields: field_info, |
| } |
| }; |
| |
| match layout.variants { |
| Variants::Single { index } => { |
| if !adt_def.variants().is_empty() && layout.fields != FieldsShape::Primitive { |
| debug!("print-type-size `{:#?}` variant {}", layout, adt_def.variant(index).name); |
| let variant_def = &adt_def.variant(index); |
| let fields: Vec<_> = variant_def.fields.iter().map(|f| f.name).collect(); |
| (vec![build_variant_info(Some(variant_def.name), &fields, layout)], None) |
| } else { |
| (vec![], None) |
| } |
| } |
| |
| Variants::Multiple { tag, ref tag_encoding, .. } => { |
| debug!( |
| "print-type-size `{:#?}` adt general variants def {}", |
| layout.ty, |
| adt_def.variants().len() |
| ); |
| let variant_infos: Vec<_> = adt_def |
| .variants() |
| .iter_enumerated() |
| .map(|(i, variant_def)| { |
| let fields: Vec<_> = variant_def.fields.iter().map(|f| f.name).collect(); |
| build_variant_info(Some(variant_def.name), &fields, layout.for_variant(cx, i)) |
| }) |
| .collect(); |
| |
| ( |
| variant_infos, |
| match tag_encoding { |
| TagEncoding::Direct => Some(tag.size(cx)), |
| _ => None, |
| }, |
| ) |
| } |
| } |
| } |
| |
| fn variant_info_for_generator<'tcx>( |
| cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, |
| layout: TyAndLayout<'tcx>, |
| def_id: DefId, |
| substs: ty::SubstsRef<'tcx>, |
| ) -> (Vec<VariantInfo>, Option<Size>) { |
| let Variants::Multiple { tag, ref tag_encoding, tag_field, .. } = layout.variants else { |
| return (vec![], None); |
| }; |
| |
| let (generator, state_specific_names) = cx.tcx.generator_layout_and_saved_local_names(def_id); |
| let upvar_names = cx.tcx.closure_saved_names_of_captured_variables(def_id); |
| |
| let mut upvars_size = Size::ZERO; |
| let upvar_fields: Vec<_> = substs |
| .as_generator() |
| .upvar_tys() |
| .zip(upvar_names) |
| .enumerate() |
| .map(|(field_idx, (_, name))| { |
| let field_layout = layout.field(cx, field_idx); |
| let offset = layout.fields.offset(field_idx); |
| upvars_size = upvars_size.max(offset + field_layout.size); |
| FieldInfo { |
| kind: FieldKind::Upvar, |
| name: Symbol::intern(&name), |
| offset: offset.bytes(), |
| size: field_layout.size.bytes(), |
| align: field_layout.align.abi.bytes(), |
| } |
| }) |
| .collect(); |
| |
| let mut variant_infos: Vec<_> = generator |
| .variant_fields |
| .iter_enumerated() |
| .map(|(variant_idx, variant_def)| { |
| let variant_layout = layout.for_variant(cx, variant_idx); |
| let mut variant_size = Size::ZERO; |
| let fields = variant_def |
| .iter() |
| .enumerate() |
| .map(|(field_idx, local)| { |
| let field_layout = variant_layout.field(cx, field_idx); |
| let offset = variant_layout.fields.offset(field_idx); |
| // The struct is as large as the last field's end |
| variant_size = variant_size.max(offset + field_layout.size); |
| FieldInfo { |
| kind: FieldKind::GeneratorLocal, |
| name: state_specific_names.get(*local).copied().flatten().unwrap_or( |
| Symbol::intern(&format!(".generator_field{}", local.as_usize())), |
| ), |
| offset: offset.bytes(), |
| size: field_layout.size.bytes(), |
| align: field_layout.align.abi.bytes(), |
| } |
| }) |
| .chain(upvar_fields.iter().copied()) |
| .collect(); |
| |
| // If the variant has no state-specific fields, then it's the size of the upvars. |
| if variant_size == Size::ZERO { |
| variant_size = upvars_size; |
| } |
| |
| // This `if` deserves some explanation. |
| // |
| // The layout code has a choice of where to place the discriminant of this generator. |
| // If the discriminant of the generator is placed early in the layout (before the |
| // variant's own fields), then it'll implicitly be counted towards the size of the |
| // variant, since we use the maximum offset to calculate size. |
| // (side-note: I know this is a bit problematic given upvars placement, etc). |
| // |
| // This is important, since the layout printing code always subtracts this discriminant |
| // size from the variant size if the struct is "enum"-like, so failing to account for it |
| // will either lead to numerical underflow, or an underreported variant size... |
| // |
| // However, if the discriminant is placed past the end of the variant, then we need |
| // to factor in the size of the discriminant manually. This really should be refactored |
| // better, but this "works" for now. |
| if layout.fields.offset(tag_field) >= variant_size { |
| variant_size += match tag_encoding { |
| TagEncoding::Direct => tag.size(cx), |
| _ => Size::ZERO, |
| }; |
| } |
| |
| VariantInfo { |
| name: Some(Symbol::intern(&ty::GeneratorSubsts::variant_name(variant_idx))), |
| kind: SizeKind::Exact, |
| size: variant_size.bytes(), |
| align: variant_layout.align.abi.bytes(), |
| fields, |
| } |
| }) |
| .collect(); |
| |
| // The first three variants are hardcoded to be `UNRESUMED`, `RETURNED` and `POISONED`. |
| // We will move the `RETURNED` and `POISONED` elements to the end so we |
| // are left with a sorting order according to the generators yield points: |
| // First `Unresumed`, then the `SuspendN` followed by `Returned` and `Panicked` (POISONED). |
| let end_states = variant_infos.drain(1..=2); |
| let end_states: Vec<_> = end_states.collect(); |
| variant_infos.extend(end_states); |
| |
| ( |
| variant_infos, |
| match tag_encoding { |
| TagEncoding::Direct => Some(tag.size(cx)), |
| _ => None, |
| }, |
| ) |
| } |
