Re: Optimization techniques

On 4/18/2019 4:07 AM, George Neuner wrote:
> On Wed, 17 Apr 2019 09:42:21 -0400 (EDT), "Rick C. Hodgin"
> <rick.c.hodgin@gmail.com> wrote:
>
>> Are there resources someone can point me to for learning more about
>> time-honored, long-established, safely applied, optimization
>> techniques for a C/C++ like language?
>
> There really aren't many "safe" optimizations you can do before you
> run into pointer aliasing problems in C. Almost any modern compiler
> text will cover the bulk of them.


I'm not sure what that is by its name, but I'll start there. Thank
you, George.


> [Great reading list, thanks. Floating add and multiply commute but
> they don't associate. a+b should be the sams as b+a, but (a+b)+c not
> the same as a+(b+c). -John]


I think the goal for floating point engines in moving forward is no
longer to only be exceeding fast under IEEE-754 or its relatives, but
there should be a new model introduced into silicon which carries out
computations that are truly accurate, which either an arbitrary pre-
cision engine which will admittedly be slower and be accurate out only
to some finite degree and inaccurate beyond that, or some kind of sym-
bolic tree-based algorithm which doesn't actually conduct the final
computation until the tree has been updated to its final form, and is
then, and only then, computed, allowing for cancellations and reduc-
tions to be made, which I believe is what happens in apps like Maple
and Mathematica.


--
Rick C. Hodgin
[I think you're conflating different things in the FP stuff. The
sorts of analysis that Maple and Mathematica do require looking
at potentially large amounts of data and deciding on the fly how
to do the calculations. It might be reasonable to do some of that
in hardware, but I think most of it is too complicated. -John]

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