RFR(S):8242429:Better implementation for signed extract

[Vladimir Ivanov]

> Webrev: http://cr.openjdk.java.net/~yzhang/ericliu/8242429/webrev.01/

Looks good.

Have you tested it through submit repo?

Best regards,
Vladimir Ivanov

> [Tests]
> Jtreg hotspot::hotspot_all_no_apps, jdk::jdk_core and langtools::tier1.
> No new failure found.
> 
> JMH: A simple JMH case [1] on AArch64 and AMD64 machines.
> 
> For AArch64, one platform has no obvious improvement, but on others the
> performance gain is 7.3%~32.7%.
> 
> For AMD64, one platform has no obvious improvement, but on others the
> performance gain is 13.7%~32.4%.
> 
> A simple test case [2] has checked the correctness for some corner
> cases.
> 
> [1] https://bugs.openjdk.java.net/secure/attachment/87712/IdealNegate.java
> [2] https://bugs.openjdk.java.net/secure/attachment/87713/SignExtractTest.java
> 
> 
> Thanks,
> Eric
>