8168996: C2 crash at postaloc.cpp:140 : assert(false) failed: unexpected yanked node Summary: Prevent MemBarAcquire from keeping a LoadNNode alive by adding it to the worklist if it is the only user of a DecodeNNode. Reviewed-by: kvn

^build/
^dist/
^drop/
^drop_included/
^webrev
/nbproject/private/
^.hgtip