Re: [Qemu-devel] [PATCH] Fix NaN handling in softfloat

[Daniel Jacobowitz]

On Sat, Nov 03, 2007 at 06:35:48PM +0100, Aurelien Jarno wrote:
> Hi all,
> 
> The current softfloat implementation changes qNaN into sNaN when 
> converting between formats, for no reason. The attached patch fixes
> that. It also fixes an off-by-one in the extended double precision
> format (aka floatx80), the mantissa is 64-bit long and not 63-bit
> long.
> 
> With this patch applied all the glibc 2.7 floating point tests
> are successfull on MIPS and MIPSEL.

FYI, I posted a similar patch and haven't had time to get back to it.
Andreas reminded me that we need to make sure at least one mantissa
bit is set.  If we're confident that the common NaN format will
already have some bit other than the qnan/snan bit set, this is fine;
otherwise, we might want to forcibly set some other mantissa bit.

-- 
Daniel Jacobowitz
CodeSourcery