RFR (M) 8152753: C1 intrinsics for CompareAndExchange (x86)

[Roland Westrelin]

>>   http://cr.openjdk.java.net/~shade/8152753/webrev.01/

That c1_LIR.cpp change:

931       if (!opCompareAndSwap->_exchange)
do_input(opCompareAndSwap->_cmp_value);

doesn't seem right. Why do you need it?

Roland.