[aarch64-port-dev ] RFR: 8135231: add support for vectorizing double precision sqrt

[Andrew Haley]

I'm not seeing vectorization of the test case.  Please let me know
exactly how to see the effect.

I'm doing this:

/home/aph/hs-comp/build/linux-aarch64-normal-server-slowdebug/images/jdk/bin/java \
-XX:+SuperWordReductions -XX:LoopUnrollLimit=250 -XX:LoopMaxUnroll=16 \
-XX:CompileThresholdScaling=0.1 -classpath \
JTwork/classes/compiler/loopopts/superword -XX:+PrintCompilation \
SumRedSqrt_Double

I see a ton of faddd instructions, but no vector ops.

Thanks,
Andrew.