[PATCH] Flag to enable IEEE-754 friendly FP optimizations

Sergey Dmitrouk sdmitrouk at accesssoftek.com
Thu Jan 22 07:05:26 PST 2015


Ping.

On Mon, Jan 12, 2015 at 10:21:32AM +0200, Sergey Dmitrouk wrote:
> Ping.
>
> On Mon, Dec 22, 2014 at 11:36:10AM +0200, Sergey Dmitrouk wrote:
> > Hello Hal,
> >
> > it took me some time to change the way it works, but now new changes also
> > cover some cases missed in the previous version.
> >
> > After thinking a bit more I introduced two separate flags for exceptions
> > and rounding, as you suggested.  At the moment rounding flag just
> > disables folding, I'm not sure how to actually check that result of
> > operation doesn't depend on rounding mode.  This prevents early
> > optimization for something like "1.0 + 2.0", so might need adjustments
> > if there is a way to check whether rounding is important for particular
> > operation.
> >
> > Using fast-math flags instead of function attributes didn't remove that
> > much flags as they are not used in code related to constant expression
> > folding.  In fact, I had to add one more "Strict" argument to be able to
> > prevent conversion to constant expressions, which results in losing
> > fast-math flags.
> >
> > Please find updated set of patches in the attachment.
> >
> > Thanks,
> > Sergey



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