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add naive_layout_of query

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This commit is contained in:
Moulins 2023-06-19 15:29:31 +02:00
parent e2a7ba2771
commit cb8b1d1bc9
19 changed files with 294 additions and 49 deletions
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197
compiler/rustc_ty_utils/src/layout.rs
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@ -5,7 +5,8 @@ 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,
IntegerExt, LayoutCx, LayoutError, LayoutOf, NaiveLayout, TyAndLayout, TyAndNaiveLayout,
MAX_SIMD_LANES,
};
use rustc_middle::ty::{
self, AdtDef, EarlyBinder, GenericArgsRef, ReprOptions, Ty, TyCtxt, TypeVisitableExt,
@ -24,14 +25,14 @@ use crate::errors::{
use crate::layout_sanity_check::sanity_check_layout;
pub fn provide(providers: &mut Providers) {
*providers = Providers { layout_of, ..*providers };
*providers = Providers { layout_of, naive_layout_of, ..*providers };
}
#[instrument(skip(tcx, query), level = "debug")]
fn layout_of<'tcx>(
fn naive_layout_of<'tcx>(
tcx: TyCtxt<'tcx>,
query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
) -> Result<TyAndLayout<'tcx>, &'tcx LayoutError<'tcx>> {
) -> Result<TyAndNaiveLayout<'tcx>, &'tcx LayoutError<'tcx>> {
let (param_env, ty) = query.into_parts();
debug!(?ty);
@ -51,18 +52,45 @@ fn layout_of<'tcx>(
}
};
if ty != unnormalized_ty {
// Ensure this layout is also cached for the normalized type.
return tcx.naive_layout_of(param_env.and(ty));
}
let cx = LayoutCx { tcx, param_env };
let layout = naive_layout_of_uncached(&cx, ty)?;
Ok(TyAndNaiveLayout { ty, layout })
}
#[instrument(skip(tcx, query), level = "debug")]
fn layout_of<'tcx>(
tcx: TyCtxt<'tcx>,
query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
) -> Result<TyAndLayout<'tcx>, &'tcx LayoutError<'tcx>> {
let (param_env, unnormalized_ty) = query.into_parts();
let param_env = param_env.with_reveal_all_normalized(tcx);
// `naive_layout_of` takes care of normalizing the type.
let naive = tcx.naive_layout_of(query)?;
let ty = naive.ty;
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)?;
if !naive.is_underestimate_of(layout) {
bug!(
"the estimated naive layout is bigger than the actual layout:\n{:#?}\n{:#?}",
naive,
layout,
);
}
let layout = TyAndLayout { ty, layout };
record_layout_for_printing(&cx, layout);
sanity_check_layout(&cx, &layout);
Ok(layout)
@ -75,6 +103,132 @@ fn error<'tcx>(
cx.tcx.arena.alloc(err)
}
fn naive_layout_of_uncached<'tcx>(
cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
ty: Ty<'tcx>,
) -> Result<NaiveLayout, &'tcx LayoutError<'tcx>> {
let tcx = cx.tcx;
let dl = cx.data_layout();
let scalar =
|value: Primitive| NaiveLayout { min_size: value.size(dl), min_align: value.align(dl).abi };
let univariant = |fields: &mut dyn Iterator<Item = Ty<'tcx>>,
repr: &ReprOptions|
-> Result<NaiveLayout, &'tcx LayoutError<'tcx>> {
// For simplicity, ignore inter-field padding; this may underestimate the size.
// FIXME(reference_niches): Be smarter and implement something closer to the real layout logic.
let mut layout = NaiveLayout::EMPTY;
for field in fields {
let field = cx.naive_layout_of(field)?;
layout = layout
.concat(&field, cx)
.ok_or_else(|| error(cx, LayoutError::SizeOverflow(ty)))?;
}
if let Some(align) = repr.align {
layout.min_align = std::cmp::max(layout.min_align, align);
}
if let Some(pack) = repr.pack {
layout.min_align = std::cmp::min(layout.min_align, pack);
}
Ok(layout.pad_to_align())
};
debug_assert!(!ty.has_non_region_infer());
Ok(match *ty.kind() {
// Basic scalars
ty::Bool => scalar(Int(I8, false)),
ty::Char => scalar(Int(I32, false)),
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(_) => scalar(Pointer(dl.instruction_address_space)),
// The never type.
ty::Never => NaiveLayout::EMPTY,
// Potentially-wide pointers.
ty::Ref(_, _, _) | ty::RawPtr(_) => {
// TODO(reference_niches): handle wide pointers
scalar(Pointer(AddressSpace::DATA))
}
ty::Dynamic(_, _, ty::DynStar) => {
let ptr = scalar(Pointer(AddressSpace::DATA));
ptr.concat(&ptr, cx).ok_or_else(|| error(cx, LayoutError::SizeOverflow(ty)))?
}
// Arrays and slices.
ty::Array(element, _count) => {
let element = cx.naive_layout_of(element)?;
NaiveLayout {
min_size: Size::ZERO, // TODO(reference_niches): proper array size
min_align: element.min_align,
}
}
ty::Slice(element) => {
NaiveLayout { min_size: Size::ZERO, min_align: cx.naive_layout_of(element)?.min_align }
}
ty::Str => NaiveLayout::EMPTY,
// Odd unit types.
ty::FnDef(..) | ty::Dynamic(_, _, ty::Dyn) | ty::Foreign(..) => NaiveLayout::EMPTY,
// FIXME(reference_niches): try to actually compute a reasonable layout estimate,
// without duplicating too much code from `generator_layout`.
ty::Generator(..) => NaiveLayout::EMPTY,
ty::Closure(_, ref substs) => {
univariant(&mut substs.as_closure().upvar_tys(), &ReprOptions::default())?
}
ty::Tuple(tys) => univariant(&mut tys.iter(), &ReprOptions::default())?,
ty::Adt(def, substs) if def.is_union() => {
let repr = def.repr();
let only_variant = &def.variants()[FIRST_VARIANT];
only_variant.fields.iter().try_fold(NaiveLayout::EMPTY, |layout, f| {
let mut fields = std::iter::once(f.ty(tcx, substs));
univariant(&mut fields, &repr).map(|l| layout.union(&l))
})?
}
ty::Adt(def, substs) => {
// For simplicity, assume that any discriminant field (if it exists)
// gets niched inside one of the variants; this will underestimate the size
// (and sometimes alignment) of enums.
// FIXME(reference_niches): Be smarter and actually take into accoount the discriminant.
let repr = def.repr();
def.variants().iter().try_fold(NaiveLayout::EMPTY, |layout, v| {
let mut fields = v.fields.iter().map(|f| f.ty(tcx, substs));
let vlayout = univariant(&mut fields, &repr)?;
Ok(layout.union(&vlayout))
})?
}
// 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(error(cx, 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(error(cx, LayoutError::Unknown(ty)));
}
})
}
fn univariant_uninterned<'tcx>(
cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
ty: Ty<'tcx>,
@ -146,6 +300,14 @@ fn layout_of_uncached<'tcx>(
ty::Ref(_, pointee, _) | ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => {
let mut data_ptr = scalar_unit(Pointer(AddressSpace::DATA));
if !ty.is_unsafe_ptr() {
match cx.naive_layout_of(pointee) {
// TODO(reference_niches): actually use the naive layout to set
// reference niches; the query is still kept to for testing purposes.
Ok(_) => (),
// This can happen when computing the `SizeSkeleton` of a generic type.
Err(LayoutError::Unknown(_)) => (),
Err(err) => return Err(err),
}
data_ptr.valid_range_mut().start = 1;
}
@ -558,18 +720,15 @@ fn layout_of_uncached<'tcx>(
}
// 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(error(cx, 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(error(cx, LayoutError::Unknown(ty)));
ty::Alias(..)
| ty::Bound(..)
| ty::GeneratorWitness(..)
| ty::GeneratorWitnessMIR(..)
| ty::Infer(_)
| ty::Placeholder(..)
| ty::Param(_)
| ty::Error(_) => {
unreachable!("already rejected by `naive_layout_of`");
}
})
}