ptr: optimize {swap,replace,read}_ptr
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@ -14,6 +14,7 @@ use cast;
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use option::{Option, Some, None};
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use sys;
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use unstable::intrinsics;
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use util::swap;
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#[cfg(not(test))] use cmp::{Eq, Ord};
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use uint;
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@ -177,9 +178,9 @@ pub unsafe fn swap_ptr<T>(x: *mut T, y: *mut T) {
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let t: *mut T = &mut tmp;
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// Perform the swap
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copy_memory(t, x, 1);
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copy_memory(x, y, 1);
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copy_memory(y, t, 1);
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copy_nonoverlapping_memory(t, x, 1);
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copy_memory(x, y, 1); // `x` and `y` may overlap
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copy_nonoverlapping_memory(y, t, 1);
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// y and t now point to the same thing, but we need to completely forget `tmp`
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// because it's no longer relevant.
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@ -192,7 +193,7 @@ pub unsafe fn swap_ptr<T>(x: *mut T, y: *mut T) {
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*/
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#[inline]
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pub unsafe fn replace_ptr<T>(dest: *mut T, mut src: T) -> T {
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swap_ptr(dest, &mut src);
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swap(cast::transmute(dest), &mut src); // cannot overlap
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src
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}
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@ -202,8 +203,7 @@ pub unsafe fn replace_ptr<T>(dest: *mut T, mut src: T) -> T {
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#[inline(always)]
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pub unsafe fn read_ptr<T>(src: *mut T) -> T {
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let mut tmp: T = intrinsics::uninit();
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let t: *mut T = &mut tmp;
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copy_memory(t, src, 1);
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copy_nonoverlapping_memory(&mut tmp, src, 1);
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tmp
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}
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