Fedor Sergeev wrote:
> On Tue, Apr 21, 2009 at 12:21:12AM +0200, Roland Mainz wrote:
> > Fedor Sergeev wrote:
> > > On Fri, Apr 17, 2009 at 05:42:08PM +0200, Roland Mainz wrote:
> > > > Is there somewhere a document which describes which functions are
> > > > available as builtin functions via Sun Studio's "-xbuiltin=%all" option
> > > > ?
> > >
> > > Not really.
> > > We do not handle it as "direct" builtins, that is headers do not contain
> > > compiler specific symbols, like builtin_sqrt or whatnot.
> >
> > Erm... what do you mean with that ?
> 
> Well, you just dont want to know then ;)

*beep*-wrong-answer-switching-to-'curious-mode'-*beep* :-)

... what does it mean ? Where does -xbuiltin=... differ from gcc4.x's
"builtin" function support ?

> > > Optimizing compiler components (backends) are able to optimize nearly 
> > > every
> > > standard function (function that is declared in a standard header).
> >
> > How does that work ?
> 
> Compiler knows that function declaration comes from a standard system header
> (it reads these declarations from those headers after all).
> Then this function is considered to be a standard function and is subject for 
> -xbuiltin
> optimizations.

How do these optimisations look like ? Does it require that the compile
have inline code sequences in some kind of library or is this something
else ?

> > > Different backends on different platforms have different ideas on what
> > > is a good function to optimize.
> > >
> > > What are you trying to solve with that document?
> >
> > I'd like to enable only a few builtin functions (basically only those
> > which make sense from a performance point-of-view (like the string copy
> > functions) and those which do not alter |errno|).
> 
> Sorry, I do not believe this is possible.

Why (quick look at cc(1) shows that "-xbuiltin" seems to support only
"%all" and "%none" as values and not function names... is that correct
?) ? 

----

Bye,
Roland

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