RFR (S) : 8014362 : Need to expose some processor features via Unsafe interface
john.r.rose at oracle.com
Thu May 16 16:05:39 PDT 2013
On May 16, 2013, at 3:57 PM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
> X86_ONLY() is ugly. I would prefer to have something similar to VM_Version::has_fast_idiv(): VM_Version::has_clmul(). The drawback is you have to define it on all platforms. Which may be not bad if some of them have similar feature.
It is probably the least-bad ugly for this use case. We are not likely to support this clmul-based algorithm other than on this one point-case.
> This is an other reason I don't like your approach of using x86 specific code in libraries. What if arm64 will have instructions to optimize crc?
By then we will have figured out a better way to manage these processor-sensitive algorithms. If that better way is not VM_Version::has_clmul, then that would be wasted generalization. More likely, I think, we will have a sun.misc.Processor API and a way to manage specialized code generation from JDK code.
Worst case is we add ARM64_ONLY(PUTPROP(...)), plus a bunch of ugly ARM assembly code, etc. The PUTPROP is the least of our problems!
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