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Re: Fix for bz#13658 - using fsincos on x86-64
- From: "Carlos O'Donell" <carlos at systemhalted dot org>
- To: Andreas Jaeger <aj at suse dot com>
- Cc: libc-alpha <libc-alpha at sourceware dot org>, jakub at redhat dot com, Andreas Schwab <schwab at redhat dot com>
- Date: Sun, 12 Feb 2012 23:49:05 -0500
- Subject: Re: Fix for bz#13658 - using fsincos on x86-64
- References: <4F343F56.3040402@suse.com>
On Thu, Feb 9, 2012 at 4:49 PM, Andreas Jaeger <aj@suse.com> wrote:
> We should not use the inaccurate fsincos instruction on x86-64 (see bugzilla
> and the discussion on the gcc mailing list). Let's just remove the double
> version and use the IBM libm sincos implementation.
>
> Unfortunately the same fix does not work for the long double version - since
> there's no sincos implementation for ldbl-96 yet ;-(. Jakub, you wrote the
> ldb-128 versions - do you have any suggestions?
>
> Andreas
>
> 2012-02-09 ?Andreas Jaeger ?<aj@suse.de>
>
> ? ? ? ?[BZ#13658]
> ? ? ? ?* sysdeps/x86_64/fpu/s_sincos.S: Remove, let's not use the
> ? ? ? ?inaccurate fsincos instruction.
Is there any reason we don't do long-form argument reduction (as
normal sin and cos do) followed by fsincos?
Does this effect i386 which also uses fsincos?
Does this also effect m68k which uses fsincos (M68000PM/AD REV.1
states loss of accuracy if the input is > 10^20).
Cheers,
Carlos.