Date: Sat, 25 May 2019 15:53:57 -0700 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Yuri <yuri@rawbw.com> Cc: Konstantin Belousov <kostikbel@gmail.com>, Freebsd hackers list <freebsd-hackers@freebsd.org> Subject: Re: What is the portable 128-bit floating point type? Message-ID: <20190525225357.GA56490@troutmask.apl.washington.edu> In-Reply-To: <e13bc70d-4d7e-3407-a0a0-14a64f94addd@rawbw.com> References: <eb15d9e4-c1d4-3886-a3b7-1264c12396cd@rawbw.com> <20190525200437.GV2748@kib.kiev.ua> <e13bc70d-4d7e-3407-a0a0-14a64f94addd@rawbw.com>
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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? > gcc version 5 or 6 and up comes with libquadmath. It is a software implementation of IEEE 128-bit floating point math. You need sparc64 to have a 128-bit hardware support. -- Steve
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