JDK 9-fastdebug b66 hit assertion when ran with "-Xcomp -XX:+BackgroundCompilation -XX:-SplitIfBlocks" options on Linux-x64 platform.

Running next command give following result(hs_err_pid21754.log and replay_pid21754.log are attached):
java -Xcomp -XX:+BackgroundCompilation -XX:-SplitIfBlocks
 739 Opaque1 === _ 1243 137 [[ 716 ]]
# To suppress the following error report, specify this argument
# after -XX: or in .hotspotrc: SuppressErrorAt=/phaseX.cpp:952
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/HUDSON/workspace/9-2-build-linux-amd64/jdk9/2755/hotspot/src/share/vm/opto/phaseX.cpp:952), pid=21754, tid=0x00007fc20771a700
# assert(false) failed: modified node is not on IGVN._worklist
#
# JRE version: Java(TM) SE Runtime Environment (9.0-b66) (build 1.9.0-ea-fastdebug-b66)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (1.9.0-ea-fastdebug-b66 compiled mode linux-amd64 compressed oops)
# Core dump will be written. Default location: Core dumps may be processed with "/usr/share/apport/apport %p %s %c" (or dumping to /home/dmitry/bundles/jdk9/b66/fastdebug/bin/core.21754)
#
# An error report file with more information is saved as:
# /home/dmitry/bundles/jdk9/b66/fastdebug/bin/hs_err_pid21754.log
...


JDK 8u45-fastdebug not affected(not hit assertion with these options)