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From "Nathan Beyer" <ndbe...@apache.org>
Subject Re: [drlvm] tests failing on linux (Ubuntu 7.04-dev) with Quad Xeon P3
Date Sat, 31 Mar 2007 21:48:24 GMT
On 3/31/07, Rana Dasgupta <rdasgupt@gmail.com> wrote:
> On 3/31/07, Gregory Shimansky <gshimansky@gmail.com> wrote:
> > Nathan Beyer wrote:
> > > On 3/30/07, Nathan Beyer <ndbeyer@apache.org> wrote:
> > > Okay, I'm trying that out now. Can the JIT be a little smarter and not
> > >use instructions that aren't available? We certainly can't limit
> > > available platforms to P4 or newer.
> >
> > I hope JIT gurus can answer this. I know that JIT can use x87 stack
> > instead of SSE for floating point, but other P4 specific instructions
> > may still be present in the code. I know at least one place in DRLVM
> > where mfence, sfence and lfence are used explicitly in inline assembly.
> >
> We have had these discussions before when discussing JIT plans etc. We
> did discuss that the floating point operations generated by jitrino,
> as contributed, uses sse2 and that porting to the x87 stack was a TBD.
>
> We also stated in these discussions that the "minimum machine model"
> was a P4, which implies that it was an assumption that P4 instructions
> were available  and P4 specific optimization patterns could be used. I
> am sure that these discussions are there in the archives.
>
> Nathan, would it be at all possible for you to move to a P4 machine? I
> am not aware of any JIT plan to be P3 compatible, maybe Pavel or
> Mikhail Fursov can comment.

No, I can't just move to a P4 machine. I think a more appropriate
question would be "can our intended consumers just upgrade?"

I realize there's probably more "interest" in 64-bit platforms, since
they're a bit newer and sexier, but honestly I think Harmony will have
many more consumers on older devices.

-Nathan

>
> Thanks,
> Rana
>

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