Unstable if traps are supposed to be taken rarely. Below patch introduces a 'StressUnstableIfTraps' flag that forces unstable if traps to be taken randomly and thus potentially triggering intermittent bugs. It works by adding another if before the unstable if that checks a "random" condition at runtime and then either takes the trap or executes the original, unstable if:
https://github.com/openjdk/jdk/compare/master...TobiHartmann:jdk:JDK-8335334

The stress option also has the nice side effect of triggering re-compilation of methods that would otherwise not be re-compiled (see JDK-8335843).