RFR: 8278868: Add x86 vectorization support for Long.bitCount() [v8]

[Vamsi Parasa]

On Fri, 7 Jan 2022 02:13:49 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> Tests failed on aarch64 systems and avx2 x86.

Could you please let me know if the failing test is test/hotspot/jtreg/compiler/vectorization/TestPopCountVectorLong.java ?
Added additional checks (shown below) to make sure it runs on an x86 machine that has AVX3.
* @requires vm.compiler2.enabled
* @requires os.arch=="x86" | os.arch=="i386" | os.arch=="amd64" | os.arch=="x86_64"

This test exits gracefully on a Skylake machine which doesn't have AVX3.

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PR: https://git.openjdk.java.net/jdk/pull/6857