Date: Mon, 20 Feb 2012 23:20:54 -0800 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: "Thomas D. Dean" <tomdean@speakeasy.org> Cc: freebsd-amd64@freebsd.org Subject: Re: Gcc46 and 128 Bit Floating Point Message-ID: <20120221072053.GA10302@troutmask.apl.washington.edu> In-Reply-To: <4F3EC0B4.6050107@speakeasy.org> References: <4F3EA37F.9010207@speakeasy.org> <CAGE5yCpvF0-b1iKAVGbya=fUNaYbGyrpj1PHSQxw4BvycNMLDg@mail.gmail.com> <4F3EC0B4.6050107@speakeasy.org>
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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
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