See the discussion there, as well as this hotspot-runtime-dev thread:
http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2014-November/013230.html
Most people are in agreement this flag outlived its usefulness, and should be removed.
- duplicates
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                    JDK-8064777 Remove -XX:+-UseCompilerSafepoints flag -           
- Closed
 
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                    JDK-8064749 -XX:-UseCompilerSafepoints breaks safepoint rendezvous -           
- Resolved
 
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