Re: What is wrong with Bugzilla? [Was: Re: GCC and Floating-Point]

[Vincent Lefevre <vincent+gcc at vinc17 dot org>]

On 2005-05-30 22:18:14 +0200, Toon Moene wrote:
> Vincent Lefevre wrote:
[...]
> >First there is a bug in GCC concerning casts and assignments
> >(see ISO/IEC 9899: 5.1.2.3#13, 6.3.1.5#2 and 6.3.1.8#2).
> >
> >But even this were fixed, many users would still complain.
> >That's why I think that the Linux kernel should set the CPU
> >in double-precision mode, like some other OS's (MS Windows,
> >*BSD) -- but this is off-topic here.
> 
> It's not off-topic.  In fact, Jim Wilson argued this point here:
> 
> http://gcc.gnu.org/ml/gcc/2003-08/msg01282.html
> 
> "The best pragmatic solution is probably to set the rounding control
> to 64-bits,

[double precision -- 64-bits isn't correct since it's the sign +
53-bit mantissa + extended exponent range internally]

Will gcc do that?

This isn't up to the user himself to do that.

> but then we lose access to long double which some people need, 
> and we still have excess precision problems for float."

But as I said on my page, this isn't much a problem since users
who really need *extended* precision can still set the rounding
precision to extended precision; this isn't portable, but extended
precision isn't portable anyway.

-- 
Vincent Lefèvre <vincent@vinc17.org> - Web: <http://www.vinc17.org/>
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Work: CR INRIA - computer arithmetic / SPACES project at LORIA