Re: [Qemu-devel] [PATCH 1/9] TCG "sync" op

[Edgar E. Iglesias]

On Fri, Oct 16, 2009 at 05:52:21PM +0200, Aurelien Jarno wrote:
> On Fri, Oct 16, 2009 at 02:38:47PM +0200, Ulrich Hecht wrote:
> > sync allows concurrent accesses to locations in memory through different TCG
> > variables. This comes in handy when you are emulating CPU registers that can
> > be used as either 32 or 64 bit, as TCG doesn't know anything about aliases.
> > See the s390x target for an example.
> > 
> > Fixed sync_i64 build failure on 32-bit targets.
> 
> It don't really see the point of such a new op, especially the way it is
> used in the S390 target.

Hi,

I looked at the s390 patches and was also unsure about this sync op.
I'm not convinced it's bad but my first feeling was as Aurelien points
out that the translator shoud take care of it. Not sure though, it would
be nice to hear what other ppl think.

Another thing I noticed was the large amount of helpers. Without looking
at the details my feeling was that you could probably do more at
translation time. That kind of optimization can be done incrementally
with follow-up patches though.

Other than that the s390 series looks OK and should IMO get committed.

Nice work!

Cheers