Re: [PATCH] Handle > INF and < INF correctly in range-op-float.cc

[Jakub Jelinek <jakub@redhat.com>]

On Tue, Sep 06, 2022 at 01:47:43PM +0200, Aldy Hernandez wrote:
> Question...for !HONOR_NANS or !HONOR_INFINITIES or whatever, say the
> range for the domain is [-MIN, +MAX] for the min and max representable
> numbers.  What happens for MAX+1?  Is that undefined?  I wonder what
> real.cc does for that.

I'm afraid I have no idea.

The formats without Inf/NaN are:
spu_single_format
vax_{f,d,g}_format
arm_half_format

Never had the "pleasure" to work with any of these.
Looking at encode_vax_*, it seems both GCC internal inf and nan are
most likely are encoded as maximum or minimum representable numbers
(depending on sign), and encode_ieee_half for !fmt->has_inf does too
(for !fmt->has_nans it seems to "encode" the nan mantissa bits into
highest possible exponent).  encode_ieee_single (for spu) uses
maximum or minimum representable numbers for any infinities or nans.
What they actually do at runtime is something I can't really check,
but one would hope it is saturating...

	Jakub