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Provide a non-sse version for x86_64.

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Tobias Decking 2023-02-22 22:16:29 +01:00 • committed by GitHub
parent 97402fc580
commit c7404df069
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14
library/compiler-builtins/src/mem/x86_64.rs
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@ -173,6 +173,7 @@ pub unsafe fn compare_bytes(a: *const u8, b: *const u8, n: usize) -> i32 {
c16(a.cast(), b.cast(), n)
}
#[cfg(target_feature="sse2")]
#[inline(always)]
pub unsafe fn c_string_length(s: *const core::ffi::c_char) -> usize {
let mut n: usize;
@ -256,6 +257,19 @@ pub unsafe fn c_string_length(s: *const core::ffi::c_char) -> usize {
n
}
// Provided for scenarios like kernel development, where SSE might not
// be available.
#[cfg(not(target_feature="sse2"))]
#[inline(always)]
pub unsafe fn c_string_length(mut s: *const core::ffi::c_char) -> usize {
let mut n = 0;
while *s != 0 {
n += 1;
s = s.add(1);
}
n
}
/// Determine optimal parameters for a `rep` instruction.
fn rep_param(dest: *mut u8, mut count: usize) -> (usize, usize, usize) {
// Unaligned writes are still slow on modern processors, so align the destination address.