The idea is interesting. You would have to consider side-effects and
other similar complications that make optimization hard for the C
compiler in the first place. For example, '*x += *y; *x += *y;' is
different from '*x += 2 * (*y)' if x and y point to the same thing.
On 03/20/2012 01:55 PM, Matthew Rocklin wrote:
Ah, I see. So we would need to parse C code, do some optimization in
sympy, and then spit C code back out and presumably give it to a compiler.
SymPy does have the ability to reason about code in a way that is quite
different from a traditional compiler. (I.e. we know that sin(x)**2 +
cos(x)**2 is 1, a compiler won't). It would be interesting to hook in
some SymPy system into some standard compiler tool-chain and see what we
could do.
As a first pass we could skip over any control stuff (this might be
hard) and just look at simpler expressions. We could run over some large
body of code and tweak expressions at a local level. We might also want
to consider simplifying based on numerical issues. There was a
scicomp.stackexchange question about this
http://scicomp.stackexchange.com/questions/527/is-there-software-that-can-autogenerate-numerically-accurate-floating-point-c-ro
Really, all of these questions would be accessible once we had a code
parser. Perhaps the GSoC idea is to build a code parser for SymPy?
Anyone out there familiar with building parsers?
On Tue, Mar 20, 2012 at 10:35 AM, Andy Ray Terrel <andy.ter...@gmail.com
<mailto:andy.ter...@gmail.com>> wrote:
Well I was thinking more of taking a piece of c code, but it could be
take a python function, grab the code object and manipulate that.
What I really want is to play around with symbolic code optimizations
and since we have quite a few tools to go from symbolics to code, it
seems easy to do simple things in the other directions. I realize
this isn't super well formed but after seeing a number of these
symbolic executor papers, I think it is probably a good way to go.
-- Andy
On Tue, Mar 20, 2012 at 11:28 AM, Aaron Meurer <asmeu...@gmail.com
<mailto:asmeu...@gmail.com>> wrote:
> Isn't this just a matter of turning some variables into Symbols and
> wrapping your literals in sympify() calls, so that everything comes
> out symbolically?
>
> Aaron Meurer
>
> On Tue, Mar 20, 2012 at 9:44 AM, Matthew Rocklin
<mrock...@gmail.com <mailto:mrock...@gmail.com>> wrote:
>> I'm confused.
>>
>> Are you talking about turning a python function into a sympy
expression,
>> optimizing the sympy expression and then going back?
>>
>> What's an example use case?
>>
>> -Matt
>>
>>
>> On Tue, Mar 20, 2012 at 7:52 AM, Andy Ray Terrel
<andy.ter...@gmail.com <mailto:andy.ter...@gmail.com>>
>> wrote:
>>>
>>> We have code printer's it would be nice to take a function and
turn it
>>> into a symbolic expression. This would allow for symbolically
>>> exploring optimizations. Lots of publishing on this, I can find a
>>> reference or two (John Gunnels thesis is certainly a good read).
>>> AFAIK this is how John optimizes codes for IBM and has won him 5
>>> Gordon Bell prizes.
>>>
>>> -- Andy
>>>
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