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make black_box a NOP in Miri

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Ralf Jung 2020-08-08 10:36:16 +02:00
parent e61621c307
commit 8385146ffa
1 changed files with 3 additions and 1 deletions
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4
library/core/src/hint.rs
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@ -119,9 +119,11 @@ pub fn black_box<T>(dummy: T) -> T {
// box. This isn't the greatest implementation since it probably deoptimizes // box. This isn't the greatest implementation since it probably deoptimizes
// more than we want, but it's so far good enough. // more than we want, but it's so far good enough.
#[cfg(not(miri))] // This is just a hint, so it is fine to skip in Miri.
// SAFETY: the inline assembly is a no-op. // SAFETY: the inline assembly is a no-op.
unsafe { unsafe {
llvm_asm!("" : : "r"(&dummy)); llvm_asm!("" : : "r"(&dummy));
dummy
} }
dummy
} }