Re: TYPE_{MIN/MAX}_VALUE for floats?

[Jakub Jelinek <jakub@redhat.com>]

On Thu, Sep 22, 2022 at 05:02:19PM +0200, Aldy Hernandez wrote:
> It has always irritated me that we don't have TYPE_MIN_VALUE and
> TYPE_MAX_VALUE for floats (and for pointers for that matter).  This
> means, we have to recalculate it ad-nauseum in vrp_val_min and
> vrp_val_max.
> 
> I know we have dconstinf and dconstninf for floats, which we can just
> wrap around a TREE_REAL_CST, but it still seems like we should be more
> consistent here.  If we know the endpoint for a type, we should cache
> it in it.

This looks problematic.
While for !MODE_HAS_INFINITIES there are clear values, otherwise
the flag_finite_math_only flag has Optimization keyword, so it can change
between different functions, while a type is a global entity that can be
used by both __attribute__((optimize ("Ofast"))) and standard floating point
functions.
In some sense it is similar to TYPE_MODE which for vectors needs to be
actually a function call that decides based on the current function.
But then, having it in TYPE_*_VALUE doesn't have the benefits you want from
it...

	Jakub