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Don't field-project (.0) into SIMD types

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This commit is contained in:
Scott McMurray 2025-03-04 22:25:08 -08:00 • committed by Amanieu d'Antras
parent 89c9c8ba9c
commit 9405357868
2 changed files with 54 additions and 11 deletions
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2
library/stdarch/crates/core_arch/src/macros.rs
View file

@ -132,7 +132,7 @@ macro_rules! types {
impl crate::fmt::Debug for $name {
#[inline]
fn fmt(&self, f: &mut crate::fmt::Formatter<'_>) -> crate::fmt::Result {
crate::core_arch::simd::debug_simd_finish(f, stringify!($name), self.0)
crate::core_arch::simd::debug_simd_finish(f, stringify!($name), self.as_array())
}
}
)*);

63
library/stdarch/crates/core_arch/src/simd.rs
View file

@ -5,7 +5,7 @@
macro_rules! simd_ty {
($id:ident [$elem_type:ty ; $len:literal]: $($param_name:ident),*) => {
#[repr(simd)]
#[derive(Copy, Clone, Debug, PartialEq)]
#[derive(Copy, Clone)]
pub(crate) struct $id([$elem_type; $len]);
#[allow(clippy::use_self)]
@ -38,13 +38,32 @@ macro_rules! simd_ty {
/// Use for testing only.
// FIXME: Workaround rust@60637
#[inline(always)]
pub(crate) fn extract(self, index: usize) -> $elem_type {
assert!(index < $len);
// Now that we know this is in-bounds, use pointer arithmetic to access the right element.
let self_ptr = &self as *const Self as *const $elem_type;
unsafe {
self_ptr.add(index).read()
}
pub(crate) fn extract(&self, index: usize) -> $elem_type {
self.as_array()[index]
}
#[inline]
pub(crate) fn as_array(&self) -> &[$elem_type; $len] {
let simd_ptr: *const Self = self;
let array_ptr: *const [$elem_type; $len] = simd_ptr.cast();
// SAFETY: We can always read the prefix of a simd type as an array.
// There might be more padding afterwards for some widths, but
// that's not a problem for reading less than that.
unsafe { &*array_ptr }
}
}
impl core::cmp::PartialEq for $id {
#[inline]
fn eq(&self, other: &Self) -> bool {
self.as_array() == other.as_array()
}
}
impl core::fmt::Debug for $id {
#[inline]
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
debug_simd_finish(f, stringify!($id), self.as_array())
}
}
}
@ -53,7 +72,7 @@ macro_rules! simd_ty {
macro_rules! simd_m_ty {
($id:ident [$elem_type:ident ; $len:literal]: $($param_name:ident),*) => {
#[repr(simd)]
#[derive(Copy, Clone, Debug, PartialEq)]
#[derive(Copy, Clone)]
pub(crate) struct $id([$elem_type; $len]);
#[allow(clippy::use_self)]
@ -79,6 +98,30 @@ macro_rules! simd_m_ty {
// a simd type with exactly one element.
unsafe { simd_shuffle!(one, one, [0; $len]) }
}
#[inline]
pub(crate) fn as_array(&self) -> &[$elem_type; $len] {
let simd_ptr: *const Self = self;
let array_ptr: *const [$elem_type; $len] = simd_ptr.cast();
// SAFETY: We can always read the prefix of a simd type as an array.
// There might be more padding afterwards for some widths, but
// that's not a problem for reading less than that.
unsafe { &*array_ptr }
}
}
impl core::cmp::PartialEq for $id {
#[inline]
fn eq(&self, other: &Self) -> bool {
self.as_array() == other.as_array()
}
}
impl core::fmt::Debug for $id {
#[inline]
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
debug_simd_finish(f, stringify!($id), self.as_array())
}
}
}
}
@ -968,7 +1011,7 @@ simd_ty!(
pub(crate) fn debug_simd_finish<T: crate::fmt::Debug, const N: usize>(
formatter: &mut crate::fmt::Formatter<'_>,
type_name: &str,
array: [T; N],
array: &[T; N],
) -> crate::fmt::Result {
crate::fmt::Formatter::debug_tuple_fields_finish(
formatter,