sysdeps/i386/fpu/bits/mathinline.h

[Andreas Jaeger]

On 04/09/2012 09:27 PM, Roland McGrath wrote:
> I just became aware of AMD erratum 573
> (http://support.amd.com/us/Processor_TechDocs/41322_10h_Rev_Gd.pdf).
> It says that using "fsincos" may be unsafe, and there is little more
> information.  Previous (unrelated) fixes have already removed nearly
> all instances of this instruction from the libc/libm source code.
> The one remaining is in sysdeps/i386/fpu/bits/mathinline.h, and that
> only for the -ffast-math version of __sincos{,f,l}.
>
> This caused me to notice a few incidental things.
>
> 1. __sincos_code was missing a clobber for %eax.
>     I fixed that with commit 8de131c.
 >

Oops, our testsuite does not cover fast-math AFAIK ;-(


> 2. sysdeps/i386/fpu/bits/mathinline.h has a ton of stuff that does not
>     appear in sysdeps/x86_64/fpu/bits/mathinline.h under -m32.
>
>     Perhaps some of the i386 code is obsolete or undesireable or
>     something.  But shouldn't this be fully harmonized?  This is the
>     first time I've noticed something where an application built with
>     x86_64 headers installed and -m32 could come out drastically
>     different from the same application built with i686 headers
>     installed.
>
>     What should be done about that?

This should indeed be fully harmonized.

Andreas
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