[cfe-dev] Adding a new pragma to Clang

[Hal Finkel]

----- Original Message -----
> From: "Alp Toker" <alp at nuanti.com>
> To: "Renato Golin" <renato.golin at linaro.org>, "Clang Dev" <cfe-dev at cs.uiuc.edu>
> Cc: "Richard Smith" <richard at metafoo.co.uk>
> Sent: Monday, January 6, 2014 9:12:04 AM
> Subject: Re: [cfe-dev] Adding a new pragma to Clang
> 
> Hi Renato,
> 
> Pragmas in clang are monolithic with their own parse rules and state
> management so it's a bit of work. As such it's better to come up with
> a
> plan to support different kinds of optimization flags beyond just
> vectorization that may be needed in future, and ideally to reuse an
> existing format if a sane one exists.
> 
> One possibility is to re-use the #pragma clang diagnostic machinery,
> and
> along with it the command line parser. It has a lot of the work
> covered
> to track source locations, on/off states that you're better of not
> reimplementing.
> 
> It'd give us something like:
> 
> #pragma clang optimize push
> #pragma clang optimize "-vectorize-loops"
>      while (...) { }
> #pragma clang optimize pop
> 
> Or closer to the Microsoft pragma*:
> 
> #pragma clang optimize("vectorize-loops", on)
>      while (...) { }
> #pragma clang optimize("vectorize-loops", off)
> 
> gcc* has some interesting pragmas in this space already. Would any of
> those do what you need, or did you have a different grammar in mind?

I think he'll need something very close to the OpenMP syntax.

 -Hal

> 
> * http://msdn.microsoft.com/en-us/library/chh3fb0k.aspx
> *
> http://gcc.gnu.org/onlinedocs/gcc/Function-Specific-Option-Pragmas.html
> 
> Alp.
> 
> 
> 
> On 06/01/2014 14:05, Renato Golin wrote:
> > Hi Folks,
> >
> > I'm adding the pragma vectorize to Clang to print specific metadata
> > on
> > loops (later any lexical block), and I'm having some trouble
> > identifying the steps.
> >
> > I've added my pragma to ParsePragma, then added a vectorizer
> > context
> > to Sema to temporarily hold these values to be used on the next
> > lexical block (one at a time, recent replace old, style).
> >
> > But the only way I found to add this information into the AST was
> > via
> > traits, which doesn't look correct. Can anyone point me in the
> > right
> > direction?
> >
> > Who is the best person to review these changes?
> >
> > cheers,
> > --renato
> >
> >
> > _______________________________________________
> > cfe-dev mailing list
> > cfe-dev at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
> 
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-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory