mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Use pointer reads for better codegen in debug mode

Browse Source
This commit is contained in:
Markus Everling 2023-04-22 23:22:39 +00:00
parent 52833ccbe8
commit f1b86baf84
2 changed files with 14 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
crates/core_simd/src/lib.rs
View File

@ -2,7 +2,6 @@
#![feature(
const_ptr_read,
const_refs_to_cell,
const_transmute_copy,
convert_float_to_int,
decl_macro,
intra_doc_pointers,

18
crates/core_simd/src/vector.rs
View File

@ -163,21 +163,31 @@ impl<const LANES: usize> Swizzle<1, LANES> for Splat {
/// Converts an array to a SIMD vector.
pub const fn from_array(array: [T; LANES]) -> Self {
// SAFETY: Transmuting between `Simd<T, LANES>` and `[T; LANES]`
// is always valid.
// is always valid. We need to use `read_unaligned` here, since
// the array may have a lower alignment than the vector.
//
// FIXME: We currently use a pointer read instead of `transmute_copy` because
// it results in better codegen with optimizations disabled, but we should
// probably just use `transmute` once that works on const generic types.
//
// NOTE: This deliberately doesn't just use `Self(array)`, see the comment
// on the struct definition for details.
unsafe { core::mem::transmute_copy(&array) }
unsafe { (&array as *const [T; LANES] as *const Self).read_unaligned() }
}
/// Converts a SIMD vector to an array.
pub const fn to_array(self) -> [T; LANES] {
// SAFETY: Transmuting between `Simd<T, LANES>` and `[T; LANES]`
// is always valid.
// is always valid. No need to use `read_unaligned` here, since
// the vector never has a lower alignment than the array.
//
// FIXME: We currently use a pointer read instead of `transmute_copy` because
// it results in better codegen with optimizations disabled, but we should
// probably just use `transmute` once that works on const generic types.
//
// NOTE: This deliberately doesn't just use `self.0`, see the comment
// on the struct definition for details.
unsafe { core::mem::transmute_copy(&self) }
unsafe { (&self as *const Self as *const [T; LANES]).read() }
}
/// Converts a slice to a SIMD vector containing `slice[..LANES]`.