Date: Wed, 22 Aug 2007 10:00:07 GMT From: Bruce Evans <brde@optusnet.com.au> To: freebsd-amd64@FreeBSD.org Subject: Re: amd64/115581: [patch] -mfancy-math-387 has no effect Message-ID: <200708221000.l7MA079d068108@freefall.freebsd.org>
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The following reply was made to PR amd64/115581; it has been noted by GNATS. From: Bruce Evans <brde@optusnet.com.au> To: Simun Mikecin <numisemis@yahoo.com> Cc: Bruce Evans <brde@optusnet.com.au>, bug-followup@FreeBSD.org Subject: Re: amd64/115581: [patch] -mfancy-math-387 has no effect Date: Wed, 22 Aug 2007 19:50:17 +1000 (EST) On Tue, 21 Aug 2007, Simun Mikecin wrote: > --- Bruce Evans <brde@optusnet.com.au> wrote: >>> This PR is about -mfancy-math-387 usage when compiling 32-bit compatibility >>> libraries that are gone be used on FreeBSD/amd64. >>> As far as I can see FreeBSD's libm on i386 uses those fancy instructions (for >>> example /usr/src.current/lib/msun/i387/s_sin.S), so the same libm will be >>> used for running 32-bit apps on FreeBSD/amd64. >> Well, that's in asm so it is not affected by compiler flags. Compiler >> flags can cause the library to be not used at all in some cases where >> the library is better. > > I'm just wondering will it have a positive impact on performance if FreeBSD/i386 libm is changed > not to use that asm code with fancy instructions (just like FreeBSD/amd64 does). Maybe someday. The easy cases have already been looked at and resulted in removing the asm implementations of functions like sinf() and asin(). Bruce
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