RFR(S): 8187964: [s390][ppc]: Intrinsify Math.multiplyHigh(long, long)

[Andrew Haley]

One thought about this: we might generate better code on these
machines if we had an unsigned multiplyHigh intrinsic and did the
adjustment for signed arithmetic in Java code, where the sign
adjustment could be scheduled separately by C2.

OK, I'll get on with implementing unsignedMultiplyHigh!

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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