libjli, get_cpuid() implementation missing for MacOs, breaks libjli.so build in slowdebug

[Thomas Stüfe]

Hi all,

I see a build error when building the libjli on MacOs with slowdebug:

Undefined symbols for architecture x86_64:
  "_get_cpuid", referenced from:
      _hyperthreading_support in ergo_i586.o
      _logical_processors_per_package in ergo_i586.o
ld: symbol(s) not found for architecture x86_64


The reason seems to me that is that in ergo_i586.c, the implementation for
"get_cpuid()" is missing for the MacOS case (one is provided for solaris
and linux).

This only breaks the build in slowdebug, because the function is only used
from static functions which are not exported; so when building with
optimization (e.g. fastdebug), all these functions are thrown away by the
compiler and therefore get_cpuid() is not needed.

I opened a bug:

https://bugs.openjdk.java.net/browse/JDK-8074547

but do not provide a fix because I am not sure which way to fix this:

- one could provide an empty implementation for this function
- or one could provide a fully functional implementation

Also, maybe I overlooked something and my analysis is wrong.

What do you guys think?

Kind Regards, Thomas Stuefe