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Re: Changing x87 precision to full 63bit as default

On Thu, Nov 07, 2013 at 02:16:00PM +0100, Joerg Sonnenberger wrote:
> On Thu, Nov 07, 2013 at 07:52:43AM -0500, Greg Troxel wrote:
> > 
> >   as discussed a while ago, I would like to change the initial x87
> >   configuration to the system default, aka long double precision.
> >   This makes it possible to get working long double. A review of the libm
> >   assembler routines will follow to make sure they do correct rounding.
> > 
> > Does this change affect just i386, or also amd64?  If I follow
> > correctly, it will change the behavior of programs on amd64 that use x87
> > instructions rather than SSE, but that's an odd case, and therefore the
> > behavior of almost all actual programs on amd64 will not change.
> > Further, the floating point results on i386 will, post-patch, match the
> > results on amd64.  Explaining the above (correclty, which I may not have
> > done) belongs in the commit message.
> Normal float and double operation on AMD64 are using SSE2, so they would
> not be affected.

What about 32bit binaries running on amd64?


David Laight: david%l8s.co.uk@localhost

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