[11u] RFR(S): 8261022: Fix incorrect result of Math.abs() with char type

[Pengfei Li]

Resend

> Hi,
> 
> I'd like to backport JDK-8261022 to jdk11u.
> 
> Original JBS: https://bugs.openjdk.java.net/browse/JDK-8261022
> Modified webrev: http://cr.openjdk.java.net/~pli/rfr/8261022/backport11u/
> 
> This issue causes vectorized abs generate incorrect result when the argument
> has char type. Root cause is that the vector abs operation is not specially
> handled in computing vector element types after we enabled that in JDK-
> 8222074 in jdk13. As JDK-8222074 was backported to jdk11u, jdk11u is also
> affected.
> 
> The patch to fix this is in jdk17 now. The fix does not apply to jdk11u cleanly,
> as VectorNode::is_shift_opcode() is not defined in jdk11u. I have modified
> the patch a little bit to fit this difference.
> 
> Tested jtreg hotspot::tier1 and the newly added jtreg case. No failure after
> the modified patch.
> 
> --
> Thanks,
> Pengfei