question: private boolean isCircularNoSideEffect ( int regV , BitSet set ) { if ( ( set != null ) && set . get ( regV ) ) { return true ; } for ( SsaInsn use : useList [ regV ] ) { if ( hasSideEffect ( use ) ) { return false ; } } if ( set == null ) { set = new BitSet ( regCount ) ; } set . set ( regV ) ; for ( SsaInsn use : useList [ regV ] ) { RegisterSpec result = use . getResult ( ) ; if ( result == null || ! isCircularNoSideEffect ( result . getReg ( ) , set ) ) { return false ; } } return true ; }
target:  Returns true if the only uses of this register form a circle of operations with no side effects.