Re: [Qemu-devel] [PATCH 08/12] ARM: Return correct result for single<->double conversion of NaN

[Nathan Froyd <froydnj@codesourcery.com>]

On Tue, Nov 30, 2010 at 11:15:56AM +0000, Peter Maydell wrote:
> On 29 November 2010 19:54, Nathan Froyd <froydnj@codesourcery.com> wrote:
> > Yes, this is ugly.  Are you up for running:
> >
> >  perl -p -i -e 's/float(\d+)_is_nan/float\1_is_quiet_nan/g' target-*/*.c
> >
> > (and also carefully in fpu/*) or similar and moving the bit-twiddling
> > float_is_nan into fpu/?
> 
> I'm just compiling this up now. While I was eyeballing the results of
> the substitution, I noticed that there are some places which are almost
> certainly bugs introduced by other people not noticing that float*_is_nan()
> doesn't do what it says on the tin. Three at random:
> 
> In target-ppc/op_helper.c:helper_compute_fprf():
> 
> In target-alpha/op_helper.c:helper_cmptun():
> 
> In target-m68k/helper.c:sub_cmp_f64:
> 
> judging from the comments the author expected is_nan() to
> be true for all NaNs.
> 
> I'm not sure what we should do about these -- they look wrong
> but I don't have any of the setup to actually test whether they're
> wrong.

RTH (CC'd) is the expert on the Alpha bits.  The PPC one is obviously
wrong.  I can test the m68k one.

In any event, I think the safest course is to do the simple renaming; we
can clean up broken bits after the fact.

-Nathan