Idea: Run Time Compilation

[janderson]

janderson wrote:
> Craig Black wrote:
>> Since Walter is in the habit of adding super advanced features to D, I 
>> thought it possible that this one might eventually make it in.  As 
>> always, please let me know if I'm way off base.
>>
>> What if we could invoke the compiler from an application at run time 
>> and generate a function that would be instantiated on the heap?  The 
>> function would be defined by a text string and would be invoked via a 
>> function pointer or delegate.  This would allow a script-like 
>> capability with fully-optimized performance provided by the D 
>> compiler.  I think the D compiler would be ideal for this since it is 
>> so fast.  Since the method would be allocated on the heap dynamically, 
>> it could also be removed when it is done being used.
>>
>> Thoughts?
>>
>> -Craig
>>
>>
> 
> I like this idea (and have thought about it myself, I haven't brought it 
> up yet, because I'm still unsure what the best approach would be).
> 
> Michael Ambrash, was doing some something of similar nature for 
> Pixomatic (a very fast software renderer that looks like DirectX 7). I'm 
> pretty sure his compiler would not map directly to DMD because it needed 
> to be the fastest possible however he does point out some interesting 
> ideas.   The cool thing is, that its setup to optimise for the system it 
> is running on (kinda like java's virtual machine) of which (in Ambrash's 
> case) there are thousands of combinations.
> 
> For many case, we could change the code for that users environment write 
> the algorithm in the most otimal way for the given inputs and change 
> dymamic data to constants ect...
> 
> System cache can have a dramatic impact on performance which is why 
> code-modifcation techniques have been avoided in the past.  Ambrash 
> found that one frame was enough to allow the newly generated code to 
> propgage into cache.
> 
> If you were to encapsulate the code in a function pointer or something I 
> guess, you could have 2 stages.  1) compile the function and 2) run it. 
>  That way in step 1, DMD could push it into cache.
> 
> Here are the articles for anyone who is interested.
> http://www.ddj.com/184405765
> http://www.ddj.com/184405807
> http://www.ddj.com/184405848
> 
> Anyhow, we do have DDL.  I'm not exactly sure how the compiler/syntax 
> could do a much better job yet (I'm sure its possible).
> 
> -Joel

Humm, why do I always spell Abrash's name wrong  :(