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Re: [Qemu-devel] Another MIPS quiet NaN fix
From: |
Daniel Jacobowitz |
Subject: |
Re: [Qemu-devel] Another MIPS quiet NaN fix |
Date: |
Mon, 24 Sep 2007 11:45:26 -0400 |
User-agent: |
Mutt/1.5.15 (2007-04-09) |
On Mon, Sep 24, 2007 at 04:05:45PM +0200, Andreas Schwab wrote:
> Daniel Jacobowitz <address@hidden> writes:
>
> > Glibc's test-float failed on my qemu testing. I tracked it down to
> > these routines: if you count the bits carefully, you'll see that
> > 0x7FC00000 sets the quiet NaN bit (on most hardware - signalling NaN
> > in the MIPS case); so does a.high >> 41, which copies it from the
> > original NaN. I think this routine should not force a quiet or
> > signalling NaN, but just preserve the input NaN's signalling-ness.
>
> You may need to make sure that at least one mantissa bit is set.
I think - but am not quite sure - that this will already be the case
because the NaN will have come from some other NaN representation.
Good point, though - we can easily set the next bit, as long as we
don't fiddle with the signalling bit.
--
Daniel Jacobowitz
CodeSourcery