Re: [Sablevm-developer] SableJIT/x86 outperforms SableJIT/ppc!

[David <db...@CS...>]

On Tue, Mar 02, 2004 at 10:58:06PM -0500, Grzegorz B. Prokopski wrote:
> W li?cie z wto, 02-03-2004, godz. 17:26, David B=E9langer pisze:=20
> > Hi,
> Hi David,
>=20
> > I did a few improvements that results in super good improvements
> > in SableJIT (a retargetable JIT for SableVM) on x86.
> > Note that SableJIT on x86 now seems to outperform SableJIT on ppc.
>=20
> Whoo-ha! It sure looks good! I guess you're making this naive-JIT
> a little less naive? Smarter register allocation or ...?
>=20

I fixed a few thing and did a few improvement.  But most changes are due
to better usage of regs.


> > Some results here:
> > http://www.sable.mcgill.ca/~dbelan2/sablejit/results_2004-03-02.html
> Hmm... It may sound strange, but how come that on x86 you got inlined
> faster on all benchmarks than direct? I had some serious problems
> with it lately. What _exact_ compiler version did you use?
> (I might be wrong, but I think you stopped doing upgrades of SID at
> some point, is that so?)
>=20

I am using:
gcc-3.3 (GCC) 3.3.3 20040110 (prerelease) (Debian)

I always got better results with inlined than direct on my AMD.


> Could you run sablecc on direct and inlined you compiled (x86 only)
> and send me these two numbers? (this is my favorite test case where
> the problem is visible)
>=20

yes, I will do it either later tonight or tomorrow.

> > What is interesting is that SableJIT consists of a simple baseline
> > compiler (no optimizer) that uses a RISC model for its retargetable
> > backend.  And now, x86 which does not fit that well with the model
> > is better...
> Exactly.
>=20
> > (Yes, I know, for some benchmarks runs slower, working on that issue)
> I am looking forward to hear, at some point, the story of SableJIT
> increasing technical improvements.
>=20
> Great work!

I will not have much time for major improvements in the next few months,
I have a master thesis to start writing ASAP. :)


David

---

David B=E9langer
Graduate Student
School of Computer Science
McGill University
Office: MC226

Web page:   http://www.cs.mcgill.ca/~dbelan2/
Public key: http://www.cs.mcgill.ca/~dbelan2/public_key.txt