RFR(S): x86:8190934: Regressions on Haswell Xeon due to JDK-8178811

[Deshpande, Vivek R]

Hi Vladimir

I have a fix for the slowdown observed on haswell due to jdk-8178811.
The solution selectively generates vzeroupper when AVX2/ AVX512 instructions have been executed and before the transition to SSE code.
I tested this fix with the test case given with bug and SPECjbb2015.
Could you please review and sponsor the patch?
Webrev:
http://cr.openjdk.java.net/~vdeshpande/8190934/webrev.00/
I have also updated the bug: https://bugs.openjdk.java.net/browse/JDK-8190934

Regards,
Vivek
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