+* `-Zmiri-compare-exchange-weak-failure-rate=<rate>` changes the failure rate of
+ `compare_exchange_weak` operations. The default is `0.8` (so 4 out of 5 weak ops will fail).
+ You can change it to any value between `0.0` and `1.0`, where `1.0` means it
+ will always fail and `0.0` means it will never fail.