rustc_target/abi/mod.rs
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use std::fmt;
use std::ops::Deref;
use Float::*;
use Primitive::*;
use rustc_data_structures::intern::Interned;
use rustc_macros::HashStable_Generic;
use crate::json::{Json, ToJson};
pub mod call;
// Explicitly import `Float` to avoid ambiguity with `Primitive::Float`.
pub use rustc_abi::{Float, *};
impl ToJson for Endian {
fn to_json(&self) -> Json {
self.as_str().to_json()
}
}
rustc_index::newtype_index! {
/// The *source-order* index of a field in a variant.
///
/// This is how most code after type checking refers to fields, rather than
/// using names (as names have hygiene complications and more complex lookup).
///
/// Particularly for `repr(Rust)` types, this may not be the same as *layout* order.
/// (It is for `repr(C)` `struct`s, however.)
///
/// For example, in the following types,
/// ```rust
/// # enum Never {}
/// # #[repr(u16)]
/// enum Demo1 {
/// Variant0 { a: Never, b: i32 } = 100,
/// Variant1 { c: u8, d: u64 } = 10,
/// }
/// struct Demo2 { e: u8, f: u16, g: u8 }
/// ```
/// `b` is `FieldIdx(1)` in `VariantIdx(0)`,
/// `d` is `FieldIdx(1)` in `VariantIdx(1)`, and
/// `f` is `FieldIdx(1)` in `VariantIdx(0)`.
#[derive(HashStable_Generic)]
#[encodable]
#[orderable]
pub struct FieldIdx {}
}
rustc_index::newtype_index! {
/// The *source-order* index of a variant in a type.
///
/// For enums, these are always `0..variant_count`, regardless of any
/// custom discriminants that may have been defined, and including any
/// variants that may end up uninhabited due to field types. (Some of the
/// variants may not be present in a monomorphized ABI [`Variants`], but
/// those skipped variants are always counted when determining the *index*.)
///
/// `struct`s, `tuples`, and `unions`s are considered to have a single variant
/// with variant index zero, aka [`FIRST_VARIANT`].
#[derive(HashStable_Generic)]
#[encodable]
#[orderable]
pub struct VariantIdx {
/// Equivalent to `VariantIdx(0)`.
const FIRST_VARIANT = 0;
}
}
#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable_Generic)]
#[rustc_pass_by_value]
pub struct Layout<'a>(pub Interned<'a, LayoutS<FieldIdx, VariantIdx>>);
impl<'a> fmt::Debug for Layout<'a> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// See comment on `<LayoutS as Debug>::fmt` above.
self.0.0.fmt(f)
}
}
impl<'a> Deref for Layout<'a> {
type Target = &'a LayoutS<FieldIdx, VariantIdx>;
fn deref(&self) -> &&'a LayoutS<FieldIdx, VariantIdx> {
&self.0.0
}
}
impl<'a> Layout<'a> {
pub fn fields(self) -> &'a FieldsShape<FieldIdx> {
&self.0.0.fields
}
pub fn variants(self) -> &'a Variants<FieldIdx, VariantIdx> {
&self.0.0.variants
}
pub fn abi(self) -> Abi {
self.0.0.abi
}
pub fn largest_niche(self) -> Option<Niche> {
self.0.0.largest_niche
}
pub fn align(self) -> AbiAndPrefAlign {
self.0.0.align
}
pub fn size(self) -> Size {
self.0.0.size
}
pub fn max_repr_align(self) -> Option<Align> {
self.0.0.max_repr_align
}
pub fn unadjusted_abi_align(self) -> Align {
self.0.0.unadjusted_abi_align
}
/// Whether the layout is from a type that implements [`std::marker::PointerLike`].
///
/// Currently, that means that the type is pointer-sized, pointer-aligned,
/// and has a initialized (non-union), scalar ABI.
pub fn is_pointer_like(self, data_layout: &TargetDataLayout) -> bool {
self.size() == data_layout.pointer_size
&& self.align().abi == data_layout.pointer_align.abi
&& matches!(self.abi(), Abi::Scalar(Scalar::Initialized { .. }))
}
}
/// The layout of a type, alongside the type itself.
/// Provides various type traversal APIs (e.g., recursing into fields).
///
/// Note that the layout is NOT guaranteed to always be identical
/// to that obtained from `layout_of(ty)`, as we need to produce
/// layouts for which Rust types do not exist, such as enum variants
/// or synthetic fields of enums (i.e., discriminants) and wide pointers.
#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable_Generic)]
pub struct TyAndLayout<'a, Ty> {
pub ty: Ty,
pub layout: Layout<'a>,
}
impl<'a, Ty: fmt::Display> fmt::Debug for TyAndLayout<'a, Ty> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// Print the type in a readable way, not its debug representation.
f.debug_struct("TyAndLayout")
.field("ty", &format_args!("{}", self.ty))
.field("layout", &self.layout)
.finish()
}
}
impl<'a, Ty> Deref for TyAndLayout<'a, Ty> {
type Target = &'a LayoutS<FieldIdx, VariantIdx>;
fn deref(&self) -> &&'a LayoutS<FieldIdx, VariantIdx> {
&self.layout.0.0
}
}
/// Trait that needs to be implemented by the higher-level type representation
/// (e.g. `rustc_middle::ty::Ty`), to provide `rustc_target::abi` functionality.
pub trait TyAbiInterface<'a, C>: Sized + std::fmt::Debug {
fn ty_and_layout_for_variant(
this: TyAndLayout<'a, Self>,
cx: &C,
variant_index: VariantIdx,
) -> TyAndLayout<'a, Self>;
fn ty_and_layout_field(this: TyAndLayout<'a, Self>, cx: &C, i: usize) -> TyAndLayout<'a, Self>;
fn ty_and_layout_pointee_info_at(
this: TyAndLayout<'a, Self>,
cx: &C,
offset: Size,
) -> Option<PointeeInfo>;
fn is_adt(this: TyAndLayout<'a, Self>) -> bool;
fn is_never(this: TyAndLayout<'a, Self>) -> bool;
fn is_tuple(this: TyAndLayout<'a, Self>) -> bool;
fn is_unit(this: TyAndLayout<'a, Self>) -> bool;
fn is_transparent(this: TyAndLayout<'a, Self>) -> bool;
}
impl<'a, Ty> TyAndLayout<'a, Ty> {
pub fn for_variant<C>(self, cx: &C, variant_index: VariantIdx) -> Self
where
Ty: TyAbiInterface<'a, C>,
{
Ty::ty_and_layout_for_variant(self, cx, variant_index)
}
pub fn field<C>(self, cx: &C, i: usize) -> Self
where
Ty: TyAbiInterface<'a, C>,
{
Ty::ty_and_layout_field(self, cx, i)
}
pub fn pointee_info_at<C>(self, cx: &C, offset: Size) -> Option<PointeeInfo>
where
Ty: TyAbiInterface<'a, C>,
{
Ty::ty_and_layout_pointee_info_at(self, cx, offset)
}
pub fn is_single_fp_element<C>(self, cx: &C) -> bool
where
Ty: TyAbiInterface<'a, C>,
C: HasDataLayout,
{
match self.abi {
Abi::Scalar(scalar) => matches!(scalar.primitive(), Float(F32 | F64)),
Abi::Aggregate { .. } => {
if self.fields.count() == 1 && self.fields.offset(0).bytes() == 0 {
self.field(cx, 0).is_single_fp_element(cx)
} else {
false
}
}
_ => false,
}
}
pub fn is_adt<C>(self) -> bool
where
Ty: TyAbiInterface<'a, C>,
{
Ty::is_adt(self)
}
pub fn is_never<C>(self) -> bool
where
Ty: TyAbiInterface<'a, C>,
{
Ty::is_never(self)
}
pub fn is_tuple<C>(self) -> bool
where
Ty: TyAbiInterface<'a, C>,
{
Ty::is_tuple(self)
}
pub fn is_unit<C>(self) -> bool
where
Ty: TyAbiInterface<'a, C>,
{
Ty::is_unit(self)
}
pub fn is_transparent<C>(self) -> bool
where
Ty: TyAbiInterface<'a, C>,
{
Ty::is_transparent(self)
}
/// Finds the one field that is not a 1-ZST.
/// Returns `None` if there are multiple non-1-ZST fields or only 1-ZST-fields.
pub fn non_1zst_field<C>(&self, cx: &C) -> Option<(usize, Self)>
where
Ty: TyAbiInterface<'a, C> + Copy,
{
let mut found = None;
for field_idx in 0..self.fields.count() {
let field = self.field(cx, field_idx);
if field.is_1zst() {
continue;
}
if found.is_some() {
// More than one non-1-ZST field.
return None;
}
found = Some((field_idx, field));
}
found
}
}