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Life's too short not to use cfg_if

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This commit is contained in:
gnzlbg 2019-03-26 16:14:32 +01:00
parent 3b6b4899bf
commit 0c127e8494
2 changed files with 101 additions and 23 deletions
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43
src/libcore/hint.rs
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@ -97,36 +97,33 @@ pub fn spin_loop() {
/// elimination.
///
/// This function is a no-op, and does not even read from `dummy`.
#[inline]
#[unstable(feature = "test", issue = "27812")]
pub fn black_box<T>(dummy: T) -> T {
#[cfg(not(
any(
cfg_if! {
if #[cfg(any(
target_arch = "asmjs",
all(
target_arch = "wasm32",
target_os = "emscripten"
)
)
))] {
// we need to "use" the argument in some way LLVM can't
// introspect.
unsafe { asm!("" : : "r"(&dummy)) }
dummy
}
#[cfg(
any(
target_arch = "asmjs",
all(
target_arch = "wasm32",
target_os = "emscripten"
)
)
)] {
// asm.js and emscripten do not support inline assembly
unsafe {
let ret = crate::ptr::read_volatile(&dummy);
crate::mem::forget(dummy);
ret
))] {
#[inline]
unsafe fn black_box_impl<T>(d: T) -> T {
// these targets do not support inline assembly
let ret = crate::ptr::read_volatile(&d);
crate::mem::forget(d);
ret
}
} else {
#[inline]
unsafe fn black_box_impl<T>(d: T) -> T {
// we need to "use" the argument in some way LLVM can't
// introspect.
asm!("" : : "r"(&d));
d
}
}
}
unsafe { black_box_impl(dummy) }
}