Re: RFA: don't try to compare IEEE NaN's

[Jim Blandy <jimb at zwingli dot cygnus dot com>]

Eli Zaretskii <eliz@is.elta.co.il> writes:

> 
> > From: Jim Blandy <jimb@zwingli.cygnus.com>
> > Date: Tue,  5 Jun 2001 22:41:45 -0500 (EST)
> > 
> > !   testval.float_testval = 2.7182818284590452354;/* long_long_checkpoint */
> > !   float_resultval     = float_func ();		
> > !   testval.double_testval = 3.14159265358979323846; /* float_checkpoint */
> > !   double_resultval    = double_func ();		
> 
> I think it is better to initialize the integral members of the union
> with an explicit bit pattern, just not a pattern which gets
> interpreted as a NaN of an Inf.  With initialization such as above,
> you risk losing due to subtleties of compile-time conversion of a
> literal constant to a floating-point value.  This is a GDB test suite,
> so we are not interested in testing the compiler.

I'm not sure what you mean.  Once the test has assigned a value to
testval.float_testval, we only use that variable.  The compile-time
conversion happens exactly once, and then we always use the result of
that conversion.

I guess I need the problem explained to me in more detail.