Hello.
I have already sent a patch for roundeven implementation but I do not
know how do I commit my changes to GCC. Am I supposed to create a
branch or anything etc?
Also I have been trying to do folding for constant arguments and
inspecting for only func (func (x)) -> func (x) right now. I made some
changes to make this work including like :
+(for fns (TRUNC_ALL FLOOR_ALL CEIL_ALL ROUND_ALL ROUNDEVEN_ALL
NEARBYINT_ALL RINT_ALL)

Also, BUILT_IN_ROUNDEVEN instead of ROUNDEVEN_ALL is not working here.
Other changes regarding to this after inspecting round are included in
this patch, but this seems not working and I am surely missing
something. Do I need to include roundeven like round:

DEFINE_INT_AND_FLOAT_ROUND_FN (ROUND)

but this would require defining IROUNDEVEN in builtins.def but it is
not supposed to?

Thanks,
--Tejas

On Fri, 31 May 2019 at 19:00, Eric Gallager <egall@gwmail.gwu.edu> wrote:
>
> On 5/31/19, Nathan Sidwell <nathan@acm.org> wrote:
> > On 5/30/19 5:38 PM, Segher Boessenkool wrote:
> >> On Thu, May 30, 2019 at 07:08:45PM +0200, Martin Jambor wrote:
> >>> Interesting, I was also puzzled for a moment.  But notice that:
> >>>
> >>> int main ()
> >>> {
> >>>      _Float128 x = 18446744073709551617.5f128;
> >>>      _Float128 y = __builtin_roundf128 (x);
> >>> }
> >>>
> >>> behaves as expected... the difference is of course the suffix pegged to
> >>> the literal constant (see
> >>> https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Floating-Types.html).
> >>>
> >>> I would also expect GCC to use a larger type if a constant does not fit
> >>> into a double, but apparently that does not happen.  I would have to
> >>> check but it is probably the right behavior according to the standard.
> >>
> >> 6.4.4.2/4: "An unsuffixed floating constant has type double."  I don't
> >> think your suggestion would be okay?
> >
> > Not only that, but
> >
> > 1) there isn't a literal suffix to mean 'double', so one couldn't
> > override that extended type.
>
> There's not a standard one, but there is 'D' or 'd' as a GNU
> extension. The fact that it's nonstandard, though, is what causes some
> projects to ignore -Wunsuffixed-float-constants:
> https://lists.gnu.org/archive/html/bug-gzip/2011-11/msg00017.html
>
> > 2) how do you define 'doesn't fit'?  decimal 0.1 has a recurring binary
> > representation.  Should that become the longest floating point type?
> >
> > nathan
> >
> > --
> > Nathan Sidwell
> >