diff options
Diffstat (limited to 'compiler/rustc_transmute/src/layout/tree.rs')
| -rw-r--r-- | compiler/rustc_transmute/src/layout/tree.rs | 146 |
1 files changed, 123 insertions, 23 deletions
diff --git a/compiler/rustc_transmute/src/layout/tree.rs b/compiler/rustc_transmute/src/layout/tree.rs index 6a09be18ef9..7cf712ce9e9 100644 --- a/compiler/rustc_transmute/src/layout/tree.rs +++ b/compiler/rustc_transmute/src/layout/tree.rs @@ -1,4 +1,4 @@ -use std::ops::ControlFlow; +use std::ops::{ControlFlow, RangeInclusive}; use super::{Byte, Def, Ref}; @@ -32,6 +32,22 @@ where Byte(Byte), } +#[derive(Debug, Copy, Clone, Eq, PartialEq)] +pub(crate) enum Endian { + Little, + Big, +} + +#[cfg(feature = "rustc")] +impl From<rustc_abi::Endian> for Endian { + fn from(order: rustc_abi::Endian) -> Endian { + match order { + rustc_abi::Endian::Little => Endian::Little, + rustc_abi::Endian::Big => Endian::Big, + } + } +} + impl<D, R> Tree<D, R> where D: Def, @@ -59,22 +75,60 @@ where /// A `Tree` representing the layout of `bool`. pub(crate) fn bool() -> Self { - Self::Byte(Byte::new(0x00..=0x01)) + Self::byte(0x00..=0x01) } /// A `Tree` whose layout matches that of a `u8`. pub(crate) fn u8() -> Self { - Self::Byte(Byte::new(0x00..=0xFF)) + Self::byte(0x00..=0xFF) + } + + /// A `Tree` whose layout matches that of a `char`. + pub(crate) fn char(order: Endian) -> Self { + // `char`s can be in the following ranges: + // - [0, 0xD7FF] + // - [0xE000, 10FFFF] + // + // All other `char` values are illegal. We can thus represent a `char` + // as a union of three possible layouts: + // - 00 00 [00, D7] XX + // - 00 00 [E0, FF] XX + // - 00 [01, 10] XX XX + + const _0: RangeInclusive<u8> = 0..=0; + const BYTE: RangeInclusive<u8> = 0x00..=0xFF; + let x = Self::from_big_endian(order, [_0, _0, 0x00..=0xD7, BYTE]); + let y = Self::from_big_endian(order, [_0, _0, 0xE0..=0xFF, BYTE]); + let z = Self::from_big_endian(order, [_0, 0x01..=0x10, BYTE, BYTE]); + Self::alt([x, y, z]) } - /// A `Tree` whose layout accepts exactly the given bit pattern. - pub(crate) fn from_bits(bits: u8) -> Self { - Self::Byte(Byte::from_val(bits)) + /// A `Tree` whose layout matches `std::num::NonZeroXxx`. + #[allow(dead_code)] + pub(crate) fn nonzero(width_in_bytes: u64) -> Self { + const BYTE: RangeInclusive<u8> = 0x00..=0xFF; + const NONZERO: RangeInclusive<u8> = 0x01..=0xFF; + + (0..width_in_bytes) + .map(|nz_idx| { + (0..width_in_bytes) + .map(|pos| Self::byte(if pos == nz_idx { NONZERO } else { BYTE })) + .fold(Self::unit(), Self::then) + }) + .fold(Self::uninhabited(), Self::or) + } + + pub(crate) fn bytes<const N: usize, B: Into<Byte>>(bytes: [B; N]) -> Self { + Self::seq(bytes.map(B::into).map(Self::Byte)) + } + + pub(crate) fn byte(byte: impl Into<Byte>) -> Self { + Self::Byte(byte.into()) } /// A `Tree` whose layout is a number of the given width. - pub(crate) fn number(width_in_bytes: usize) -> Self { - Self::Seq(vec![Self::u8(); width_in_bytes]) + pub(crate) fn number(width_in_bytes: u64) -> Self { + Self::Seq(vec![Self::u8(); width_in_bytes.try_into().unwrap()]) } /// A `Tree` whose layout is entirely padding of the given width. @@ -125,13 +179,35 @@ where Self::Byte(..) | Self::Ref(..) | Self::Def(..) => true, } } -} -impl<D, R> Tree<D, R> -where - D: Def, - R: Ref, -{ + /// Produces a `Tree` which represents a sequence of bytes stored in + /// `order`. + /// + /// `bytes` is taken to be in big-endian byte order, and its order will be + /// swapped if `order == Endian::Little`. + pub(crate) fn from_big_endian<const N: usize, B: Into<Byte>>( + order: Endian, + mut bytes: [B; N], + ) -> Self { + if order == Endian::Little { + (&mut bytes[..]).reverse(); + } + + Self::bytes(bytes) + } + + /// Produces a `Tree` where each of the trees in `trees` are sequenced one + /// after another. + pub(crate) fn seq<const N: usize>(trees: [Tree<D, R>; N]) -> Self { + trees.into_iter().fold(Tree::unit(), Self::then) + } + + /// Produces a `Tree` where each of the trees in `trees` are accepted as + /// alternative layouts. + pub(crate) fn alt<const N: usize>(trees: [Tree<D, R>; N]) -> Self { + trees.into_iter().fold(Tree::uninhabited(), Self::or) + } + /// Produces a new `Tree` where `other` is sequenced after `self`. pub(crate) fn then(self, other: Self) -> Self { match (self, other) { @@ -222,17 +298,17 @@ pub(crate) mod rustc { ty::Float(nty) => { let width = nty.bit_width() / 8; - Ok(Self::number(width as _)) + Ok(Self::number(width.try_into().unwrap())) } ty::Int(nty) => { let width = nty.normalize(pointer_size.bits() as _).bit_width().unwrap() / 8; - Ok(Self::number(width as _)) + Ok(Self::number(width.try_into().unwrap())) } ty::Uint(nty) => { let width = nty.normalize(pointer_size.bits() as _).bit_width().unwrap() / 8; - Ok(Self::number(width as _)) + Ok(Self::number(width.try_into().unwrap())) } ty::Tuple(members) => Self::from_tuple((ty, layout), members, cx), @@ -249,11 +325,33 @@ pub(crate) mod rustc { .fold(Tree::unit(), |tree, elt| tree.then(elt))) } - ty::Adt(adt_def, _args_ref) if !ty.is_box() => match adt_def.adt_kind() { - AdtKind::Struct => Self::from_struct((ty, layout), *adt_def, cx), - AdtKind::Enum => Self::from_enum((ty, layout), *adt_def, cx), - AdtKind::Union => Self::from_union((ty, layout), *adt_def, cx), - }, + ty::Adt(adt_def, _args_ref) if !ty.is_box() => { + let (lo, hi) = cx.tcx().layout_scalar_valid_range(adt_def.did()); + + use core::ops::Bound::*; + let is_transparent = adt_def.repr().transparent(); + match (adt_def.adt_kind(), lo, hi) { + (AdtKind::Struct, Unbounded, Unbounded) => { + Self::from_struct((ty, layout), *adt_def, cx) + } + (AdtKind::Struct, Included(1), Included(_hi)) if is_transparent => { + // FIXME(@joshlf): Support `NonZero` types: + // - Check to make sure that the first field is + // numerical + // - Check to make sure that the upper bound is the + // maximum value for the field's type + // - Construct `Self::nonzero` + Err(Err::NotYetSupported) + } + (AdtKind::Enum, Unbounded, Unbounded) => { + Self::from_enum((ty, layout), *adt_def, cx) + } + (AdtKind::Union, Unbounded, Unbounded) => { + Self::from_union((ty, layout), *adt_def, cx) + } + _ => Err(Err::NotYetSupported), + } + } ty::Ref(lifetime, ty, mutability) => { let layout = layout_of(cx, *ty)?; @@ -268,6 +366,8 @@ pub(crate) mod rustc { })) } + ty::Char => Ok(Self::char(cx.tcx().data_layout.endian.into())), + _ => Err(Err::NotYetSupported), } } @@ -450,7 +550,7 @@ pub(crate) mod rustc { &bytes[bytes.len() - size.bytes_usize()..] } }; - Self::Seq(bytes.iter().map(|&b| Self::from_bits(b)).collect()) + Self::Seq(bytes.iter().map(|&b| Self::byte(b)).collect()) } /// Constructs a `Tree` from a union. |