138 lines
4.1 KiB
Rust
138 lines
4.1 KiB
Rust
//! Intermediate representation for the physical layout of some type.
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use super::derive::CanDerive;
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use super::ty::{Type, TypeKind, RUST_DERIVE_IN_ARRAY_LIMIT};
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use crate::clang;
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use crate::ir::context::BindgenContext;
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use std::cmp;
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/// A type that represents the struct layout of a type.
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub(crate) struct Layout {
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/// The size (in bytes) of this layout.
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pub(crate) size: usize,
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/// The alignment (in bytes) of this layout.
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pub(crate) align: usize,
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/// Whether this layout's members are packed or not.
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pub(crate) packed: bool,
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}
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#[test]
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fn test_layout_for_size() {
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use std::mem;
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let ptr_size = mem::size_of::<*mut ()>();
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assert_eq!(
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Layout::for_size_internal(ptr_size, ptr_size),
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Layout::new(ptr_size, ptr_size)
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);
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assert_eq!(
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Layout::for_size_internal(ptr_size, 3 * ptr_size),
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Layout::new(3 * ptr_size, ptr_size)
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);
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}
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impl Layout {
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/// Gets the integer type name for a given known size.
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pub(crate) fn known_type_for_size(
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ctx: &BindgenContext,
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size: usize,
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) -> Option<syn::Type> {
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Some(match size {
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16 if ctx.options().rust_features.i128_and_u128 => {
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syn::parse_quote! { u128 }
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}
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8 => syn::parse_quote! { u64 },
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4 => syn::parse_quote! { u32 },
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2 => syn::parse_quote! { u16 },
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1 => syn::parse_quote! { u8 },
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_ => return None,
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})
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}
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/// Construct a new `Layout` with the given `size` and `align`. It is not
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/// packed.
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pub(crate) fn new(size: usize, align: usize) -> Self {
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Layout {
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size,
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align,
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packed: false,
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}
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}
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fn for_size_internal(ptr_size: usize, size: usize) -> Self {
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let mut next_align = 2;
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while size % next_align == 0 && next_align <= ptr_size {
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next_align *= 2;
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}
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Layout {
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size,
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align: next_align / 2,
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packed: false,
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}
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}
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/// Creates a non-packed layout for a given size, trying to use the maximum
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/// alignment possible.
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pub(crate) fn for_size(ctx: &BindgenContext, size: usize) -> Self {
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Self::for_size_internal(ctx.target_pointer_size(), size)
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}
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/// Get this layout as an opaque type.
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pub(crate) fn opaque(&self) -> Opaque {
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Opaque(*self)
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}
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}
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/// When we are treating a type as opaque, it is just a blob with a `Layout`.
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#[derive(Clone, Debug, PartialEq, Eq)]
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pub(crate) struct Opaque(pub(crate) Layout);
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impl Opaque {
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/// Construct a new opaque type from the given clang type.
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pub(crate) fn from_clang_ty(
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ty: &clang::Type,
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ctx: &BindgenContext,
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) -> Type {
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let layout = Layout::new(ty.size(ctx), ty.align(ctx));
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let ty_kind = TypeKind::Opaque;
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let is_const = ty.is_const();
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Type::new(None, Some(layout), ty_kind, is_const)
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}
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/// Return the known rust type we should use to create a correctly-aligned
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/// field with this layout.
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pub(crate) fn known_rust_type_for_array(
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&self,
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ctx: &BindgenContext,
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) -> Option<syn::Type> {
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Layout::known_type_for_size(ctx, self.0.align)
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}
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/// Return the array size that an opaque type for this layout should have if
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/// we know the correct type for it, or `None` otherwise.
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pub(crate) fn array_size(&self, ctx: &BindgenContext) -> Option<usize> {
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if self.known_rust_type_for_array(ctx).is_some() {
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Some(self.0.size / cmp::max(self.0.align, 1))
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} else {
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None
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}
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}
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/// Return `true` if this opaque layout's array size will fit within the
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/// maximum number of array elements that Rust allows deriving traits
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/// with. Return `false` otherwise.
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pub(crate) fn array_size_within_derive_limit(
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&self,
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ctx: &BindgenContext,
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) -> CanDerive {
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if self
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.array_size(ctx)
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.map_or(false, |size| size <= RUST_DERIVE_IN_ARRAY_LIMIT)
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{
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CanDerive::Yes
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} else {
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CanDerive::Manually
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}
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}
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}
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