[RFR]: 8186461: zero: Don't use PowerPC FPU instructions on targets without FPU

Andrew Haley aph at redhat.com
Sat Aug 19 15:40:59 UTC 2017

On 19/08/17 11:31, John Paul Adrian Glaubitz wrote:
> On 08/19/2017 11:22 AM, Andrew Haley wrote:
>> That does not look right.  Surely we need an alternative
>> implementation?
> Those machines in question are usually single-CPU, so we probably
> don't need any particular inline assembly to perform atomic copy
> on these machines.

I think we do.  Can't descheduling happen at any time?

> However, there are actually machines - I have two of these - which
> have a dual-core configuration. So, using inline assembly to perform
> the atomic operation might make sense here.
> While these CPUs don't actually have an FPU, they have something
> called SPE instructions which are some sort of FPU replacement.
> I will have a closer look later to figure out whether I can find
> something in the data sheet [1].

OK, sounds good.  Otherwise we can just use a lock.

Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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