From: skaller <skaller@users.sourceforge.net>
To: Taras Glek <taras.judge@shaw.ca>
Cc: Caml List <caml-list@inria.fr>
Subject: Re: [Caml-list] JIT VM in OCaml: Impossible?
Date: Fri, 17 Aug 2007 12:50:00 +1000 [thread overview]
Message-ID: <1187319000.29691.24.camel@rosella.wigram> (raw)
In-Reply-To: <46C491E8.9010007@shaw.ca>
On Thu, 2007-08-16 at 11:05 -0700, Taras Glek wrote:
> > The question is: why would you do this? Why not just generate
> > C (or C++ as Felix does) and compile it to a shared library,
> > then link and execute it?
> >
> Because that would be bloody slow and depend on having a toolchain
> installed? For a JIT you want a fast compiler that only compiles as
> little as is needed.
Yes, it does depend on having a tool. Slow? No, not really:
[AMD64 2300 1G]:
(includes parsing the file)
skaller@rosella:/work/felix/svn/felix/felix/trunk$ time f hello
Hello World
real 0m2.073s
user 0m1.972s
sys 0m0.084s
(using cached parse)
skaller@rosella:/work/felix/svn/felix/felix/trunk$ time f hello
Hello World
real 0m1.026s
user 0m0.908s
sys 0m0.100s
(using cached binary)
skaller@rosella:/work/felix/svn/felix/felix/trunk$ time flx hello
Hello World
real 0m0.039s
user 0m0.016s
sys 0m0.012s
I suspect this is actually faster than any JIT, and there's
no question it is faster if the program is reused.
Don't forget: a program has to be compiled one way or the other.
Even Python is compiled to bytecode. The tool above (Felix)
is better than a JIT because it does whole program optimisation,
generates machine binaries.
So I don't buy 'slow' as an argument: the technique is much
FASTER than any JIT system in all aspects, in fact it IS
a JIT compiler -- it just compiles the whole program all the
way from source with disk based caching which persists over
invocations.
--
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net
next prev parent reply other threads:[~2007-08-17 2:50 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-16 14:10 Joel Reymont
2007-08-16 14:37 ` Sylvain Le Gall
2007-08-16 15:32 ` [Caml-list] " Oliver Bandel
2007-08-16 15:56 ` Joel Reymont
2007-08-16 16:15 ` Jon Harrop
2007-08-16 15:11 ` [Caml-list] " Oliver Bandel
2007-08-16 16:24 ` Gordon Henriksen
2007-08-16 17:37 ` skaller
2007-08-16 18:05 ` Taras Glek
2007-08-17 2:50 ` skaller [this message]
2007-08-17 3:09 ` Erick Tryzelaar
2007-08-17 5:42 ` skaller
2007-08-17 7:52 ` Joel Reymont
2007-08-17 8:36 ` Jon Harrop
2007-08-17 9:20 ` Joel Reymont
2007-08-17 8:39 ` Jon Harrop
2007-08-16 18:49 ` Jon Harrop
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