Date: Sat, 25 May 2019 16:13:10 -0700 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Konstantin Belousov <kostikbel@gmail.com> Cc: Yuri <yuri@rawbw.com>, Freebsd hackers list <freebsd-hackers@freebsd.org> Subject: Re: What is the portable 128-bit floating point type? Message-ID: <20190525231310.GB56490@troutmask.apl.washington.edu> In-Reply-To: <20190525210311.GW2748@kib.kiev.ua> References: <eb15d9e4-c1d4-3886-a3b7-1264c12396cd@rawbw.com> <20190525200437.GV2748@kib.kiev.ua> <e13bc70d-4d7e-3407-a0a0-14a64f94addd@rawbw.com> <20190525210311.GW2748@kib.kiev.ua>
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On Sun, May 26, 2019 at 12:03:11AM +0300, Konstantin Belousov wrote: > On Sat, May 25, 2019 at 01:50:24PM -0700, Yuri wrote: > > On 2019-05-25 13:04, Konstantin Belousov wrote: > > > Neither i386 nor amd64 have hardware-supported 128 bit floating point > > > type. long double is defined by both i386 and amd64 Unix ABI as 80 bits > > > (10 bytes) representation as defined by IEEEE FP standard and supported > > > by x87 FPU (not-SSE). The difference in size is due to the different > > > natural alignment between 32 and 64 bit ISA. > > > > > > So it looks like there is no true quad-precision float available. > > > > > > Based on this conversation https://github.com/bluescarni/mppp/issues/186 > > FreeBSD used to support __float128. Why was it removed? > No idea, it seems to be clang-specific. gcc 8.3 does accept the type. > On the other hand, I have no idea if any support is required from > libgcc (probably it is), and we almost certainly do not have it in > the base library. This is part of the problem with gfortran finding the wrong libgcc_s.so. -- Steve
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