JDK-8252482 : disable cbcond instructions on SPARC64
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We will disable usage of cbcond instructions on all SPARC64 CPUs.
Verified by David Buck.
As opposed to completely disabling cbcond, we make UseCBCond default to false when:
JDK 7/8: is_sparc64() returns true
JDK 11: if any of the three Athena instruction sets are supported
As the only SPARC64 chips that support cbcond also all support at least 2 (gen1 and gen2) of the Athena instruction extensions, in effect the JDK 11 change disables cbcond for all SPARC64 platforms.
These changes only impact Fujitsu's SPARC64 CPUs. Cbcond remains enabled by default on Oracle's SPARC CPUs.