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hint: Make spin_loop_hint a side-effect for all targets #77924

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hint: Make spin_loop_hint a side-effect for all targets #77924

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9 changes: 9 additions & 0 deletions library/core/src/hint.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -93,6 +93,15 @@ pub fn spin_loop() {
unsafe { crate::arch::arm::__yield() };
}
}
// This makes sure that spin_loop is always a side-effect on all platfomrs,
// allowing users to work around https://github.com/rust-lang/rust/issues/28728
// Remove when that bug is fixed.
#[cfg(not(miri))]
// SAFETY: the inline assembly is a no-op.
unsafe {
// FIXME: Cannot use `asm!` because it doesn't support MIPS and other architectures.
llvm_asm!("" : : : : "volatile");
}
}

/// An identity function that *__hints__* to the compiler to be maximally pessimistic about what
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