RFR: 8255799: AArch64: CPU_A53MAC feature may be set incorrectly

Tue Nov 3 23:08:59 UTC 2020

On Tue, 3 Nov 2020 16:58:58 GMT, Anton Kozlov <akozlov at openjdk.org> wrote:

> JDK-8255716 (#983) uncovered that os::processor_count on Linux can be not equal to number of cores reported in /proc/cpuinfo. The latter historically was used to decide CPU_A53MAC feature. This patch restores feature detection based on /proc/cpuinfo.
> 
> Testing: linux -version
> Unfortunately I cannot test windows/aarch64, CC: @lewurm @luhenry

Tested slowdebug build on Windows+Arm64 with this patch, and smoked tested it with `jtreg:tier1_compiler_1` successfully.

Change itself looks go to me too (but I'm not a reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/1039