compiler: Empty out rustc_target::abi

1 files changed, 269 insertions, 0 deletions

diff --git a/compiler/rustc_abi/src/layout/ty.rs b/compiler/rustc_abi/src/layout/ty.rs
new file mode 100644
index 00000000000..9f26c98df86
--- /dev/null
+++ b/compiler/rustc_abi/src/layout/ty.rs
@@ -0,0 +1,269 @@
+use std::fmt;
+use std::ops::Deref;
+
+use Float::*;
+use Primitive::*;
+use rustc_data_structures::intern::Interned;
+use rustc_macros::HashStable_Generic;
+
+pub mod call;
+
+// Explicitly import `Float` to avoid ambiguity with `Primitive::Float`.
+pub use rustc_abi::{Float, *};
+
+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
+    }
+}