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Date: Thu, 30 May 2019 21:38:00 -0000
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Martin Jambor <mjambor@suse.cz>
Cc: Tejas Joshi <tejasjoshi9673@gmail.com>, gcc@gcc.gnu.org, hubicka@ucw.cz
Subject: Re: About GSOC.
Message-ID: <20190530213839.GF31586@gate.crashing.org>
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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?


Segher