[Cython] Draft for compile-time calculation inliner

[Robert Bradshaw]

I disagree, I think parse trees are a great place to put many  
optimizations--for instance GCC performs many of its optimizations at  
that level.

- Robert

On Mar 15, 2008, at 2:52 AM, Gary Furnish wrote:

> While I've liked your previous ideas, parse trees are not the correct
> way to do optimizations in my opinion.  This would dramatically
> increase Cython compile time by orders of magnitude for one.  If we
> really wanted to do this we should build dependency graphs (I'm
> currently working on code that does this for classes) for all
> functions and then use some more standard algorithms.  (It is easy to
> optimize your example with graphs, it is significantly more
> complicated using the parse tree).  Doing this properly is no small
> undertaking as what you are essentially asking for is a full
> optimizing compiler (without register allocation, granted).
> Furthermore we should probably only attempt this after cython can
> bootstrap itself, as its going to be tough to keep compile times
> reasonable while cython is still written in python.  While this task
> is simple to describe, there are thousands of  devils in the details.
> I'm hesitant to call this a good idea without someone experienced in
> writing compilers willing to work on it close to full time.
>
> On 3/15/08, Dag Sverre Seljebotn <dagss at student.matnat.uio.no> wrote:
>> http://wiki.cython.org/enhancements/inlining
>>
>>  As I think this is possible in a one or two week timeframe, I ask  
>> of you
>>  all to tell me what obvious things I am missing completely and  
>> where I did
>>  a wrong turn in my reasoning :-)
>>
>>  I copy and paste:
>>
>>  Why?
>>
>>  - It leaves the way open for a hassle-free operator overloading  
>> syntax -
>>  use the same operator overloading conventions that Python use  
>> even for
>>  wrapped C library types without worrying about performance.
>>
>>  - A convenient tool for doing compile-time calculations and having
>>  parametrized code written at compile-time. The creative use C++'s  
>> template
>>  syntax has gotten over the years should demonstrate that the  
>> inlining the
>>  GCC compiler does is not sufficient for advanced use cases (see
>>  http://ubiety.uwaterloo.ca/~tveldhui/papers/Expression-Templates/ 
>> exprtmpl.html,
>>  Blitz++ etc., basically using the C++ template system to inline  
>> vector
>>  multiplications etc. that's written dynamically according to vector
>>  sizes).
>>
>>  Dag Sverre
>>
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