Re: [svn:parrot] r36057 - in trunk: . config/auto config/auto/format config/gen/config_h include/parrot src t/compilers/imcc/syn t/op

On Tue, Jan 27, 2009 at 10:24:46AM -0800, [email protected] wrote:

> -                            gen_sprintf_call(tc, &info, ch);
> -                            ts = cstr2pstr(tc);
> +                            /* check for Inf and NaN values */
> +                            if (thefloat == PARROT_FLOATVAL_INF_POSITIVE) {
> +                                ts = cstr2pstr(PARROT_CSTRING_INF_POSITIVE);
> +                            }
> +                            else if (thefloat == PARROT_FLOATVAL_INF_NEGATIVE) {
> +                                ts = cstr2pstr(PARROT_CSTRING_INF_NEGATIVE);
> +                            }
> +                            /* XXX for some reason, this comparison isn't working
> +                            else if (thefloat == PARROT_FLOATVAL_NAN_QUIET) {

No, it is working :-)

NaN != NaN.

Hence why <=> has 4 possible return values.

> +                                ts = cstr2pstr(PARROT_CSTRING_NAN_QUIET);
> +                            }
> +                            */
> +                            else if (thefloat != thefloat) {

The above is the valid test for a NaN.

Note, Intel chose that the default optimiser setting on their compiler should
be buggy. (Advice from Klortho #11912). The perl 5 Linux hints file suggests
that one needs to add -we147 to enable correct floating point behaviour.

The best test that I'm aware of for "is it NaN or Inf?" is val != val * 0;
Then, NaN is val != val, +Inf is val > 0, -Inf is val < 0;

Nicholas Clark