rust/crates/hir-ty/src/layout.rs

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//! Compute the binary representation of a type
use std::sync::Arc;
use base_db::CrateId;
use chalk_ir::{AdtId, TyKind};
use hir_def::{
layout::{
Abi, FieldsShape, Integer, Layout, LayoutCalculator, LayoutError, Primitive, ReprOptions,
RustcEnumVariantIdx, Scalar, Size, StructKind, TargetDataLayout, Variants, WrappingRange,
},
LocalFieldId,
};
use stdx::never;
use crate::{db::HirDatabase, Interner, Substitution, Ty};
use self::adt::struct_variant_idx;
pub use self::{
adt::{layout_of_adt_query, layout_of_adt_recover},
target::target_data_layout_query,
};
macro_rules! user_error {
($x: expr) => {
return Err(LayoutError::UserError(format!($x)))
};
}
mod adt;
mod target;
struct LayoutCx<'a> {
db: &'a dyn HirDatabase,
krate: CrateId,
}
impl LayoutCalculator for LayoutCx<'_> {
type TargetDataLayoutRef = Arc<TargetDataLayout>;
fn delay_bug(&self, txt: &str) {
never!("{}", txt);
}
fn current_data_layout(&self) -> Arc<TargetDataLayout> {
self.db.target_data_layout(self.krate)
}
}
fn scalar_unit(dl: &TargetDataLayout, value: Primitive) -> Scalar {
Scalar::Initialized { value, valid_range: WrappingRange::full(value.size(dl)) }
}
fn scalar(dl: &TargetDataLayout, value: Primitive) -> Layout {
Layout::scalar(dl, scalar_unit(dl, value))
}
pub fn layout_of_ty(db: &dyn HirDatabase, ty: &Ty, krate: CrateId) -> Result<Layout, LayoutError> {
let cx = LayoutCx { db, krate };
let dl = &*cx.current_data_layout();
Ok(match ty.kind(Interner) {
TyKind::Adt(AdtId(def), subst) => db.layout_of_adt(*def, subst.clone())?,
TyKind::Scalar(s) => match s {
chalk_ir::Scalar::Bool => Layout::scalar(
dl,
Scalar::Initialized {
value: Primitive::Int(Integer::I8, false),
valid_range: WrappingRange { start: 0, end: 1 },
},
),
chalk_ir::Scalar::Char => Layout::scalar(
dl,
Scalar::Initialized {
value: Primitive::Int(Integer::I32, false),
valid_range: WrappingRange { start: 0, end: 0x10FFFF },
},
),
chalk_ir::Scalar::Int(i) => scalar(
dl,
Primitive::Int(
match i {
chalk_ir::IntTy::Isize => dl.ptr_sized_integer(),
chalk_ir::IntTy::I8 => Integer::I8,
chalk_ir::IntTy::I16 => Integer::I16,
chalk_ir::IntTy::I32 => Integer::I32,
chalk_ir::IntTy::I64 => Integer::I64,
chalk_ir::IntTy::I128 => Integer::I128,
},
true,
),
),
chalk_ir::Scalar::Uint(i) => scalar(
dl,
Primitive::Int(
match i {
chalk_ir::UintTy::Usize => dl.ptr_sized_integer(),
chalk_ir::UintTy::U8 => Integer::I8,
chalk_ir::UintTy::U16 => Integer::I16,
chalk_ir::UintTy::U32 => Integer::I32,
chalk_ir::UintTy::U64 => Integer::I64,
chalk_ir::UintTy::U128 => Integer::I128,
},
false,
),
),
chalk_ir::Scalar::Float(f) => scalar(
dl,
match f {
chalk_ir::FloatTy::F32 => Primitive::F32,
chalk_ir::FloatTy::F64 => Primitive::F64,
},
),
},
TyKind::Tuple(len, tys) => {
let kind = if *len == 0 { StructKind::AlwaysSized } else { StructKind::MaybeUnsized };
let fields = tys
.iter(Interner)
.map(|k| layout_of_ty(db, k.assert_ty_ref(Interner), krate))
.collect::<Result<Vec<_>, _>>()?;
let fields = fields.iter().collect::<Vec<_>>();
let fields = fields.iter().collect::<Vec<_>>();
cx.univariant(dl, &fields, &ReprOptions::default(), kind).ok_or(LayoutError::Unknown)?
}
TyKind::Array(element, count) => {
let count = match count.data(Interner).value {
chalk_ir::ConstValue::Concrete(c) => match c.interned {
hir_def::type_ref::ConstScalar::Int(x) => x as u64,
hir_def::type_ref::ConstScalar::UInt(x) => x as u64,
hir_def::type_ref::ConstScalar::Unknown => {
user_error!("unknown const generic parameter")
}
_ => user_error!("mismatched type of const generic parameter"),
},
_ => return Err(LayoutError::HasPlaceholder),
};
let element = layout_of_ty(db, element, krate)?;
let size = element.size.checked_mul(count, dl).ok_or(LayoutError::SizeOverflow)?;
let abi = if count != 0 && matches!(element.abi, Abi::Uninhabited) {
Abi::Uninhabited
} else {
Abi::Aggregate { sized: true }
};
let largest_niche = if count != 0 { element.largest_niche } else { None };
Layout {
variants: Variants::Single { index: struct_variant_idx() },
fields: FieldsShape::Array { stride: element.size, count },
abi,
largest_niche,
align: element.align,
size,
}
}
TyKind::Slice(element) => {
let element = layout_of_ty(db, element, krate)?;
Layout {
variants: Variants::Single { index: struct_variant_idx() },
fields: FieldsShape::Array { stride: element.size, count: 0 },
abi: Abi::Aggregate { sized: false },
largest_niche: None,
align: element.align,
size: Size::ZERO,
}
}
// Potentially-wide pointers.
TyKind::Ref(_, _, pointee) | TyKind::Raw(_, pointee) => {
let mut data_ptr = scalar_unit(dl, Primitive::Pointer);
if matches!(ty.kind(Interner), TyKind::Ref(..)) {
data_ptr.valid_range_mut().start = 1;
}
// let pointee = tcx.normalize_erasing_regions(param_env, pointee);
// if pointee.is_sized(tcx.at(DUMMY_SP), param_env) {
// return Ok(tcx.intern_layout(LayoutS::scalar(cx, data_ptr)));
// }
let unsized_part = struct_tail_erasing_lifetimes(db, pointee.clone());
let metadata = match unsized_part.kind(Interner) {
TyKind::Slice(_) | TyKind::Str => {
scalar_unit(dl, Primitive::Int(dl.ptr_sized_integer(), false))
}
TyKind::Dyn(..) => {
let mut vtable = scalar_unit(dl, Primitive::Pointer);
vtable.valid_range_mut().start = 1;
vtable
}
_ => {
// pointee is sized
return Ok(Layout::scalar(dl, data_ptr));
}
};
// Effectively a (ptr, meta) tuple.
cx.scalar_pair(data_ptr, metadata)
}
TyKind::FnDef(_, _) => layout_of_unit(&cx, dl)?,
TyKind::Str => Layout {
variants: Variants::Single { index: struct_variant_idx() },
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,
},
TyKind::Never => Layout {
variants: Variants::Single { index: struct_variant_idx() },
fields: FieldsShape::Primitive,
abi: Abi::Uninhabited,
largest_niche: None,
align: dl.i8_align,
size: Size::ZERO,
},
TyKind::Dyn(_) | TyKind::Foreign(_) => {
let mut unit = layout_of_unit(&cx, dl)?;
match unit.abi {
Abi::Aggregate { ref mut sized } => *sized = false,
_ => user_error!("bug"),
}
unit
}
TyKind::Function(_) => {
let mut ptr = scalar_unit(dl, Primitive::Pointer);
ptr.valid_range_mut().start = 1;
Layout::scalar(dl, ptr)
}
TyKind::Closure(_, _)
| TyKind::OpaqueType(_, _)
| TyKind::Generator(_, _)
| TyKind::GeneratorWitness(_, _) => return Err(LayoutError::NotImplemented),
TyKind::AssociatedType(_, _)
| TyKind::Error
| TyKind::Alias(_)
| TyKind::Placeholder(_)
| TyKind::BoundVar(_)
| TyKind::InferenceVar(_, _) => return Err(LayoutError::HasPlaceholder),
})
}
fn layout_of_unit(cx: &LayoutCx<'_>, dl: &TargetDataLayout) -> Result<Layout, LayoutError> {
cx.univariant::<RustcEnumVariantIdx, &&Layout>(
dl,
&[],
&ReprOptions::default(),
StructKind::AlwaysSized,
)
.ok_or(LayoutError::Unknown)
}
fn struct_tail_erasing_lifetimes(db: &dyn HirDatabase, pointee: Ty) -> Ty {
match pointee.kind(Interner) {
TyKind::Adt(AdtId(adt), subst) => match adt {
&hir_def::AdtId::StructId(i) => {
let data = db.struct_data(i);
let mut it = data.variant_data.fields().iter().rev();
match it.next() {
Some((f, _)) => field_ty(db, i.into(), f, subst),
None => pointee,
}
}
_ => pointee,
},
_ => pointee,
}
}
fn field_ty(
db: &dyn HirDatabase,
def: hir_def::VariantId,
fd: LocalFieldId,
subst: &Substitution,
) -> Ty {
db.field_types(def)[fd].clone().substitute(Interner, subst)
}
#[cfg(test)]
mod tests;