HLVM

HLVM

[David McClain]

Wow! Thanks for that much more substantive feedback on HLVM.

I am not intimately familiar with LLVM. I am surprised that JIT can  
offer speedups over statically compiled code.

And forgive me for asking what may seem a question with an obvious  
answer... but now don't you also have to change the OCaml compiler  
back end to target the HLVM?

Dr. David McClain
dbm@refined-audiometrics.com

Re: [Caml-list] HLVM

[Alp Mestan]

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On Sun, Sep 27, 2009 at 6:57 PM, David McClain <dbm@refined-audiometrics.com
> wrote:

> And forgive me for asking what may seem a question with an obvious
> answer... but now don't you also have to change the OCaml compiler back end
> to target the HLVM?
>

The current "example" provided with HLVM is a very minimal ML-style language
implementation. However, there was a Jane Street Summer Project proposal to
port OCaml's current compiler to HLVM/LLVM. It hasn't been accepted.

But if HLVM gets more complete and enhanced, yeah, it would require porting
the compiler to target HLVM/LLVM.

Regards.

-- 
Alp Mestan
http://blog.mestan.fr/
http://alp.developpez.com/

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HLVM...

[David McClain]

... remember too, in signal and image processing applications,  
converting to raw machine integers and plowing ahead is often  
counterproductive.

Rather we need saturating arithmetic to avoid abrupt transitions on  
overflow conditions, or modulo addressing. Neither of these is native  
to SSM, and have to be synthesized. DSP chips on the other hand almost  
always offer these variations implicitly or explicitly.


Dr. David McClain
dbm@refined-audiometrics.com

HLVM...

[David McClain]

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Interesting quote from a Wikipedia article on JIT compiling...

"...For instance, most Common Lisp systems have a compile function  
which can compile new functions created during the run. This provides  
many of the advantages of JIT, but the programmer, rather than the  
runtime, is in control of what parts of the code are compiled. This  
can also compile dynamically generated code, which can, in many  
scenarios, provide substantial performance advantages over statically  
compiled code, as well as over most JIT systems."


Dr. David McClain
dbm@refined-audiometrics.com




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HLVM

[David McClain]

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Yes, I saw those references already. Still not enough information...

What, in particular, sets HLVM apart. Surely not just the native  
machine types?

Are you handling array references in some unusually efficient manner?  
Are you avoiding unnecessary copy-on-writes of large arrays by some  
form of whole-program analysis? I still don't have a handle on HLVM...

>
> http://www.ffconsultancy.com/ocaml/hlvm/

> http://flyingfrogblog.blogspot.com/2009/03/performance-ocaml-vs-hlvm-beta-04.html

Dr. David McClain
dbm@refined-audiometrics.com




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