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Date: Mon, 20 Feb 2012 23:20:54 -0800
From: Steve Kargl <sgk@troutmask.apl.washington.edu>
To: "Thomas D. Dean" <tomdean@speakeasy.org>
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Cc: freebsd-amd64@freebsd.org
Subject: Re: Gcc46 and 128 Bit Floating Point
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On Fri, Feb 17, 2012 at 01:03:48PM -0800, Thomas D. Dean wrote:
> On 02/17/12 11:31, Peter Wemm wrote:
> >On Fri, Feb 17, 2012 at 10:59 AM, Thomas D. Dean<tomdean@speakeasy.org>  
> >wrote:
> >[..]
> >>gcc46 is generating 80-bit floating point instructions.
> >>
> >>The gcc docs state gcc46 will generate 128-bit instructions.
> >>
> >>I can get gfortran46 to generate 128-bit instructions.
> >>
> >>How do I get gcc46 to generate 128-bit floating point instructions?
> >
> >"As of gcc 4.3, a quadruple precision is also supported on x86, but as
> >the nonstandard type __float128 rather than long double."
> >
> 
> AS it turns out, gcc46 does not support long double.

Yes, it does.

> Or, is it just 
> because the port lang/gcc46 uses the system libc, which is gcc 4.2.1?

I seems it is that you don't understand the types.

float --------> 24 bit significand, 32 bit size.
double -------> 53 bit significand, 64 bit size.
long double --> 53 bit significand, 80 bit size, i386
long double --> 64 bit significand, 80 bit size, x86_64
long double --> 113 bit significand, 128 bit size, sparc64
__float128 ---> 113 bit significand, 128 bit size, i386, x86_64

-- 
Steve