[pypy-dev] Re: Fwd: michele.simionato at gmail.com: ACCU conference aftermath

[Michael Hudson]

"Steven H. Rogers" <steve at shrogers.com> writes:

> Michael Hudson wrote:
>> Armin Rigo <arigo at tunes.org> writes:
>> 
>>>Hi all,
>>>
>>> I took the liberty to forward here the following e-mail from
>>> Michele Simionato, as it contains interesting links.
>> I think Michele is using a different definition of "JIT" to me...
>> 
>>>As I told you in the conference, I think you should check in the
>>>Lisp/Scheme world where there is an astonishingly amount of
>>>knowledge about JIT and in general about compiling to C code fast.
>> While not disputing the general thrust of this, I would say that I
>> am
>> aware of *no* work on using run-time information to improve
>> compilation in a Lisp or a Scheme system (this surprises me, and I
>> have looked for it a bit, but I may have missed something).
>> 
>
> While not automated like a Java JIT, the compiler is an integral part
> of the language in Lisp and may be used by the application programmer
> to compile code at run time.

Eh, this sounds too hostile, but: were you under the impression that I
didn't know this?

>> Also, very few serious common lisp implementations go via C (the only
>> one I can think of that does is GCL).
>> 
>
> CLISP is written in largely in C.  SBCL has replaced much of the
> assembler in CMUCL with C for greater portability.

That's not what I or Michele said, though: GCL translates the code the
user supplies into C and calls gcc to compile it to object code (I
understand; I've never used it).

>> 
>>>Relevant projects I know of are:
>>>
>>>- SBCL, a JIT compiler for Common Lisp;
>> SBCL is not a JIT compiler in the sense I understand the words.
>> 
>
> What is your understanding of JIT compiler?

Well, at the minimum performing compiling-type activities at what the
user would consider runtime, but unless this takes advantage of
runtime information it's fairly pointless.  I don't count typing code
into the REPL for this -- do you?

Cheers,
mwh

-- 
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