On Fri, Jul 29, 2016 at 12:13:01PM +1000, Benjamin Herrenschmidt wrote: > On Fri, 2016-07-29 at 06:19 +0530, Richard Henderson wrote: > > This, I'm not so keen on. > > > > (1) The helper, since it writes to registers controlled by tcg, must be > > described to clobber all registers. Which will noticeably increase memory > > traffic to ENV. For instance, you won't be able to hold the guest register > > holding the address in a host register across the call. > > Ah I wasn't aware of this. How do you describe such a clobber ? Can I describe > specifically which one is clobbered ? I didn't think TCG kept track of the > vector > halves but I must admit I'm still a bit new with TCG in general. > > I noticed other constructs doing that (passing a register number to an > opcode), > what do I do to ensure the right clobbers are there ? > > > > (2) We're going to have to teach tcg about 16-byte data types soon > > > anyway, for > > the proper emulation of 16-byte atomic operations. > > Is anybody working on this already ? I thought about that approach as > it would definitely make things easier for that and a couple of other > cases such as lq/stq.
What should I do with this in the short term? Leave it in
ppc-for-2.8, or remove it for now pending possible changes?
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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