__attribute__((optimize)) and fast-math related oddities

Michael Meissner meissner@linux.vnet.ibm.com
Tue Oct 20 22:58:00 GMT 2009


On Tue, Oct 20, 2009 at 11:13:48AM -0700, H.J. Lu wrote:
> On Tue, Oct 20, 2009 at 2:19 AM, Richard Guenther
> <richard.guenther@gmail.com> wrote:
> > On Tue, Oct 20, 2009 at 1:54 AM, tbp <tbptbp@gmail.com> wrote:
> >> On Mon, Oct 19, 2009 at 7:34 PM, Ian Lance Taylor <iant@google.com> wrote:
> >>> Please file a bug report.
> >>> __attribute__((optimize())) is definitely only half-baked.
> >> Apparently the code i've posted is just a variation around that 1 year
> >> old PR 37565 and if that doesn't work, worrying about the rest is
> >> entirely futile.
> >> Half baked you say? It's comforting to see that much optimism but
> >> couldn't the doc be adjusted a bit to reflect the fact that the baker
> >> got hit by a bus or something?
> >
> > I would rather suggest to rip out the half-baked code again.
> >
> 
> I agree. The idea is good. But the design and implementation
> are incomplete.

As the original author I do tend to agree, we've been finding all of these
places, particularly as we go to more and more tree optimizations.  However,
the question is what do we do at this particular point given it has been in the
compiler for 2 years now.  There were a number of people that did ask me for it
when I presented the initial thoughts a few years ago.

-- 
Michael Meissner, IBM
4 Technology Place Drive, MS 2203A, Westford, MA, 01886, USA
meissner@linux.vnet.ibm.com



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