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Merge pull request #312 from Ralith/elementwise-unordered-atomics 

Tidy up unordered elementwise atomic memory intrinsics
This commit is contained in:
Alex Crichton 2019-08-23 11:07:41 -07:00 committed by GitHub
parent bc57f53b5d 9775f08b1d
commit 44dc22f34d
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 12 additions and 4 deletions
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16
src/mem.rs
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@ -5,7 +5,7 @@ type c_int = i16;
#[cfg(not(target_pointer_width = "16"))] #[cfg(not(target_pointer_width = "16"))]
type c_int = i32; type c_int = i32;
use core::intrinsics::{atomic_load_unordered, atomic_store_unordered, unchecked_div}; use core::intrinsics::{atomic_load_unordered, atomic_store_unordered, exact_div};
use core::mem; use core::mem;
use core::ops::{BitOr, Shl}; use core::ops::{BitOr, Shl};
@ -63,9 +63,10 @@ pub unsafe extern "C" fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32 {
0 0
} }
// `bytes` must be a multiple of `mem::size_of::<T>()`
fn memcpy_element_unordered_atomic<T: Copy>(dest: *mut T, src: *const T, bytes: usize) { fn memcpy_element_unordered_atomic<T: Copy>(dest: *mut T, src: *const T, bytes: usize) {
unsafe { unsafe {
let n = unchecked_div(bytes, mem::size_of::<T>()); let n = exact_div(bytes, mem::size_of::<T>());
let mut i = 0; let mut i = 0;
while i < n { while i < n {
atomic_store_unordered(dest.add(i), atomic_load_unordered(src.add(i))); atomic_store_unordered(dest.add(i), atomic_load_unordered(src.add(i)));
@ -74,9 +75,10 @@ fn memcpy_element_unordered_atomic<T: Copy>(dest: *mut T, src: *const T, bytes:
} }
} }
// `bytes` must be a multiple of `mem::size_of::<T>()`
fn memmove_element_unordered_atomic<T: Copy>(dest: *mut T, src: *const T, bytes: usize) { fn memmove_element_unordered_atomic<T: Copy>(dest: *mut T, src: *const T, bytes: usize) {
unsafe { unsafe {
let n = unchecked_div(bytes, mem::size_of::<T>()); let n = exact_div(bytes, mem::size_of::<T>());
if src < dest as *const T { if src < dest as *const T {
// copy from end // copy from end
let mut i = n; let mut i = n;
@ -95,18 +97,24 @@ fn memmove_element_unordered_atomic<T: Copy>(dest: *mut T, src: *const T, bytes:
} }
} }
// `T` must be a primitive integer type, and `bytes` must be a multiple of `mem::size_of::<T>()`
fn memset_element_unordered_atomic<T>(s: *mut T, c: u8, bytes: usize) fn memset_element_unordered_atomic<T>(s: *mut T, c: u8, bytes: usize)
where where
T: Copy + From<u8> + Shl<u32, Output = T> + BitOr<T, Output = T>, T: Copy + From<u8> + Shl<u32, Output = T> + BitOr<T, Output = T>,
{ {
unsafe { unsafe {
let n = unchecked_div(bytes, mem::size_of::<T>()); let n = exact_div(bytes, mem::size_of::<T>());
// Construct a value of type `T` consisting of repeated `c`
// bytes, to let us ensure we write each `T` atomically.
let mut x = T::from(c); let mut x = T::from(c);
let mut i = 1; let mut i = 1;
while i < mem::size_of::<T>() { while i < mem::size_of::<T>() {
x = x << 8 | T::from(c); x = x << 8 | T::from(c);
i += 1; i += 1;
} }
// Write it to `s`
let mut i = 0; let mut i = 0;
while i < n { while i < n {
atomic_store_unordered(s.add(i), x); atomic_store_unordered(s.add(i), x);