Re: anonymous functions optimization - wanted for 3.4.0?

[Jaroslav Hajek]

On Sat, Sep 11, 2010 at 9:09 AM, John W. Eaton <address@hidden> wrote:
> On 11-Sep-2010, Jaroslav Hajek wrote:
>
> | On Fri, Sep 10, 2010 at 8:56 PM, Olaf Till <address@hidden> wrote:
> | > On Fri, Sep 10, 2010 at 11:52:44AM +0200, Jaroslav Hajek wrote:
> | >> hi all,
> | >>
> | >> attached is a patch that implements an interesting (IMHO) optimization
> | >> of anonymous function handles. First a bit of theory:
> | >> A number of anonymous function handles looks like this:
> | >>
> | >> h = @(par1, par2, ...) some_func (arg1, arg2, ....)
> | >>
> | >> where each argi is either a reference to some parj, or a constant, or
> | >> a variable defined in the calling context. Such a function
> | >> is called a "binder" because it merely takes some other function or
> | >> handle and binds some of its parameters to certain values.
> | >> Callback functions are often binders.
> | >>
> | >> Examples:
> | >>
> | >> @(x) size (x, 3)
> | >> @(x, y) my_func (x, my_data, y)
> | >>
> | >> The attached patch optimizes calls to binders. When Octave constructs
> | >> an anonymous handle, it attempts to detect if it's a binder. If so, it
> | >> augments the handle with information how to transform the argument
> | >> list and the "root" function's handle (or value). It then overrides
> | >> the call sequence with a fast code that transforms the argument list
> | >> and calls the root function. This eliminates the overhead of setting
> | >> up an m-function, altering the call stack, and interpreting the
> | >> function's body, making binders only incur small additive penalty to
> | >> the root function's cost.
> | >
> | > If somewhere in a stack of "binders" occurs an error (reference to a
> | > missing argument), will the error message show in which "binder" the
> | > error occurs? Olaf
> | >
> |
> | The optimized code path is only taken if all arguments are given and
> | thus no error can occur; otherwise, the normal interpreted code is
> | used.
>
> I have no objection to making a change like this for 3.4.0.
>
> Thanks,
>
> jwe
>
>

OK, I pushed the changeset.

-- 
RNDr. Jaroslav Hajek, PhD
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz