bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-def/src/layout.rs')
-rw-r--r--crates/hir-def/src/layout.rs96
1 files changed, 96 insertions, 0 deletions
diff --git a/crates/hir-def/src/layout.rs b/crates/hir-def/src/layout.rs
new file mode 100644
index 0000000000..6bb4cd94f8
--- /dev/null
+++ b/crates/hir-def/src/layout.rs
@@ -0,0 +1,96 @@
+//! Definitions needed for computing data layout of types.
+
+use std::cmp;
+
+use la_arena::{Idx, RawIdx};
+pub use rustc_abi::{
+ Abi, AbiAndPrefAlign, AddressSpace, Align, Endian, FieldsShape, Integer, IntegerType,
+ LayoutCalculator, Niche, Primitive, ReprFlags, ReprOptions, Scalar, Size, StructKind,
+ TargetDataLayout, TargetDataLayoutErrors, WrappingRange,
+};
+
+use crate::LocalEnumVariantId;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct RustcEnumVariantIdx(pub LocalEnumVariantId);
+
+impl rustc_index::vec::Idx for RustcEnumVariantIdx {
+ fn new(idx: usize) -> Self {
+ RustcEnumVariantIdx(Idx::from_raw(RawIdx::from(idx as u32)))
+ }
+
+ fn index(self) -> usize {
+ u32::from(self.0.into_raw()) as usize
+ }
+}
+
+pub type Layout = rustc_abi::LayoutS<RustcEnumVariantIdx>;
+pub type TagEncoding = rustc_abi::TagEncoding<RustcEnumVariantIdx>;
+pub type Variants = rustc_abi::Variants<RustcEnumVariantIdx>;
+
+pub trait IntegerExt {
+ fn repr_discr(
+ dl: &TargetDataLayout,
+ repr: &ReprOptions,
+ min: i128,
+ max: i128,
+ ) -> Result<(Integer, bool), LayoutError>;
+}
+
+impl IntegerExt for Integer {
+ /// Finds the appropriate Integer type and signedness for the given
+ /// signed discriminant range and `#[repr]` attribute.
+ /// N.B.: `u128` values above `i128::MAX` will be treated as signed, but
+ /// that shouldn't affect anything, other than maybe debuginfo.
+ fn repr_discr(
+ dl: &TargetDataLayout,
+ repr: &ReprOptions,
+ min: i128,
+ max: i128,
+ ) -> Result<(Integer, bool), LayoutError> {
+ // Theoretically, negative values could be larger in unsigned representation
+ // than the unsigned representation of the signed minimum. However, if there
+ // are any negative values, the only valid unsigned representation is u128
+ // which can fit all i128 values, so the result remains unaffected.
+ let unsigned_fit = Integer::fit_unsigned(cmp::max(min as u128, max as u128));
+ let signed_fit = cmp::max(Integer::fit_signed(min), Integer::fit_signed(max));
+
+ if let Some(ity) = repr.int {
+ let discr = Integer::from_attr(dl, ity);
+ let fit = if ity.is_signed() { signed_fit } else { unsigned_fit };
+ if discr < fit {
+ return Err(LayoutError::UserError(
+ "Integer::repr_discr: `#[repr]` hint too small for \
+ discriminant range of enum "
+ .to_string(),
+ ));
+ }
+ return Ok((discr, ity.is_signed()));
+ }
+
+ let at_least = if repr.c() {
+ // This is usually I32, however it can be different on some platforms,
+ // notably hexagon and arm-none/thumb-none
+ dl.c_enum_min_size
+ } else {
+ // repr(Rust) enums try to be as small as possible
+ Integer::I8
+ };
+
+ // If there are no negative values, we can use the unsigned fit.
+ Ok(if min >= 0 {
+ (cmp::max(unsigned_fit, at_least), false)
+ } else {
+ (cmp::max(signed_fit, at_least), true)
+ })
+ }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub enum LayoutError {
+ UserError(String),
+ SizeOverflow,
+ HasPlaceholder,
+ NotImplemented,
+ Unknown,
+}